Documents published in 2019 : Scipedia

A three dimensional FEM-DEM technique for predicting the evolution of fracture in geomaterials and concrete
F. Zarate, A. Cornejo Velázquez, E. Oñate

Comp. Part. Mech (2018). (prepint) Vol. 5 (3) , pp. 411-420

Abstract
This paper extends to three dimensions (3D) the computational technique developed by the authors in 2D for predicting the onset and evolution of fracture in a finite element mesh in a simple manner based on combining the finite element method (FEM) and the discrete element method (DEM) approach Zarate2D. Once a crack is detected at an element edge, discrete elements are generated at the adjacent element vertexes and a simple DEM mechanism is considered in order to follow the evolution of the crack. The combination of the DEM with simple 4-noded linear tetrahedron elements correctly captures the onset of fracture and its evolution, as shown in several 3D examples of application.
Abstract
This paper extends to three dimensions (3D) the computational technique developed by the authors in 2D for predicting the onset and evolution of fracture in a finite element [...]
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An accurate nonlocal bonded discrete element method for non linear analysis of solids. Application to concrete fracture tests (preprint)
M. Celigueta, S. Latorre, F. Arrufat, E. Oñate

Computational Particle Mechanics (2020). Vol. 7, pp. 543–553, 10.1007/s40571-019-00278-5

Abstract
We present a numerical procedure for elastic and non linear analysis (including fracture situations) of solid materials and structures using the Discrete Element Method (DEM). It can be applied to strongly cohesive frictional materials such as concrete and rocks. The method consists on defining the non-local constitutive equations at the contact interfaces between discrete particles using the information provided by the stress tensor over the neighbour particles. The method can be used with different yield surfaces and in the paper it is applied to the analysis of fracture of concrete samples. Good comparison with experimental results is obtained.
Abstract
We present a numerical procedure for elastic and non linear analysis (including fracture situations) of solid materials and structures using the Discrete Element Method (DEM). [...]
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A coupled fluid FEM-DEM technique for predicting blasting operations in tunnels
F. Zarate, J. Gonzalez, J. Miquel, R. Lohner, E. Oñate

Underground Space (2018). Vol. 3 (4), pp. 310-316, (prepint)

Abstract
We present recent developments in the coupling of the finite element method (FEM) and the discrete element method (DEM) for analysis of rock blasting operations in tunnels. The coupled FEM-DEM technique has proven to be an efficient procedure for predicting the multi-fracture of rock induced by the loads generated in blasting situations. The coupled FEM-DEM procedure is applied in the tunnel construction, as well as to gas pressure blasting pyrotechnics situations to break rock for excavation of the tunnel front. In the latter case the effect of gas explosion is modelled by solving with the FEM the equations of gas dynamics in the analysis domain. The effect of the gas forces in the underlying rock mass is modelled via an embedded fluid-structure interaction method. The efficiency of the coupled FEM-DEM technique is demonstrated in several examples of fracture tests and rock blasting problems related to tunnel engineering. The examples presented show that the combination of the DEM with simple 3-noded linear triangular elements (for 2D problems) correctly captures the onset of fractures and their evolution accounting for the penetration of the gas in the failure domain [[#cite-1|[1,2]]].
Abstract
We present recent developments in the coupling of the finite element method (FEM) and the discrete element method (DEM) for analysis of rock blasting operations in tunnels. [...]
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Decisin support system for risk assessment and management of floods
E. Oñate, J. Piazzese, J. Dolz, M. Gómez, E. Bladé

Monograph CIMNE (2005). M92

Abstract
The objective of the RAMFLOOD project is to develop and validate a new decision support system (DSS) for the risk assessment and management of emergency scenarios due to severe floods. The DSS combines environmental and geo-physical data from earth observation, with advanced computer simulation and graphical visualisation methods and artificial intelligence techniques, for generating knowledge contributing to the risk prevention of floods and the design of effective response actions maximising the safety of infrastructures and human life.
Abstract
The objective of the RAMFLOOD project is to develop and validate a new decision support system (DSS) for the risk assessment and management of emergency scenarios due to severe [...]
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Diseño de tanques cilíndricos de ferrocemento para construir en comunidades rurales de países en desarrollo
J. Maso, C. Molins, A. Aguado

Monograph CIMNE (2005). M91

Abstract
En este documento se presenta un estudio sobre el diseño y la construcción de depósitos de ferrocemento para países en vías de desarrollo. Se le da un especial énfasis al hecho de que los depósitos que se plantean están pensados para países en vías de desarrollo, porque la tecnología empleada así como los materiales tendrá una calidad notablemente inferior a la que se podría esperar de países desarrollados. Asimismo, la participación de los usuarios (a través de la supervisión de un técnico) en la construcción del depósito hace que se tienda a simplificar lo máximo posible el montaje de la estructura así como la cantidad de cálculos necesarios. En primer lugar se introduce el concepto de ferrocemento, se analizan sus propiedades, se describen sus componentes (tipo de refuerzo, proporciones de mezcla,…), se detallan algunos elementos empleados para su ejecución (encofrado, herramientas, equipo necesario,…) y se hace un breve repaso, a continuación, a las aplicaciones que hasta la fecha se le han dado al ferrocemento como material de construcción. También se incluyen los resultados correspondientes a unos ensayos realizados en un estudio sobre el diseño de tanques para países en vías de desarrollo (llevados a cabo en otra universidad) y obtenidos a través de Internet. A continuación se plantea una formulación específica para el dimensionamiento de la pared del depósito y se acompaña con algunos ejemplos de aplicación práctica en base a la formulación planteada que recogen capacidades bien diferenciadas: 10, 50 y 150m3. De este modo se recogen los diseños tipo para un depósito pequeño, mediano y grande (considerando el ámbito en el que nos encontramos y el rango en el que se mueven este tipo de estructuras). En éstos se resuelve el diseño de la solera a través de un exhaustivo análisis por Elementos Finitos de diversos modelos de solera, considerando como forma básica el casquete esférico y variando a partir de aquí la curvatura de éste así como la unión con la base de la pared. Al final de cada ejemplo propuesto se muestra un croquis detallado de la estructura, el refuerzo y las cotas correspondientes. Se incluye también un capítulo con ejemplos reales sobre depósitos de ferrocemento (concretamente se comentan la construcción de un depósito de 10m3, uno de 150m3, un depósito enterrado y el montaje de una cubierta para un tanque de ferrocemento) fruto del trabajo de investigación bibliográfica llevado a cabo a lo largo del estudio y que se ha creído conveniente incluir por su alto interés técnico. Los ejemplos además se acompañan de los detalles y mediciones de las obras. En una segunda parte, se generalizan los resultados para un rango de depósitos acotado entre un cierto valor de alturas y radios del depósito. El rango adoptado es bastante amplio, variando el radio desde 50cm hasta 10m, mientras que las alturas consideradas van de 1m hasta 3m. Se abarca, de esta manera cualquier posibilidad de dimensionamiento, por muy remota que sea. El criterio adoptado a la hora de acotar el rango de los resultados ha sido el de proporcionar alturas razonables para facilitar la construcción y diámetros no mayores de los que parece ser que este material llega a resultar más viable que otro como por ejemplo el hormigón (aunque este tema es discutible). Estos resultados se han resumido a modo de tablas organizadas según las variables estudiadas sean variables de dimensionamiento (capacidad, espesores, cuantías de armadura, flecha de solera) o de cuantificación de materiales (peso de acero, volumen de arena, peso de cemento), dando lugar en total a 12 tablas, cuyo método de empleo se describe en el propio capítulo. Además para tener una idea comparativa de los resultados ofrecidos por las tablas se analizan diversos ejemplos comparando las cantidades propuestos por diversos autores y los obtenidos a partir del empleo de las tablas. Cabe destacar que estas tablas no pretenden ser un método estricto, sino más bien orientativo (en fase experimental), en el que se recomienda al menos la presencia de un técnico para valorar los resultados y apreciar los detalles necesarios que lógicamente no se incluyen en las tablas como herramientas, elementos de atado, encofrado, personal necesario, etc.
Abstract
En este documento se presenta un estudio sobre el diseño y la construcción de depósitos de ferrocemento para países en vías de desarrollo. [...]
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An overlay J2 viscoelastic viscoplastic viscodamage model for stable shear localization problems
M. Cervera, M. Chiumenti

Monograph CIMNE (2003). M85

Abstract
This work formulates a relatively simple isotropic local Overlay J2-Viscoelastic-Viscoplastic-Viscodamage constitutive model (O-J2-VVV) which encompasses the merits of both the plastic and continuum damage formulations. The plastic component of the model account for inelastic permanent strains, while the damage component account for loss of stiffness. The plas- tic and damage softening moduli are regularized according to the material mode II fracture energy and the element size. The Orthogonal SubGrid Stabilization Method (OSGS ) is used to ensure existance and uniquess of the solution for strain shear strain localization processes, attaining global and local stability of the corresponding discrete finite element formulation. Consistent residual viscosity is used to enhance robustness and convergence of the formulation. Numerical examples show that the formulation derived is versatily, fully stable and remarkably robust, The solutions obtained are completely mesh independent, unlike those obtained with the ill-posed standard approaches.
Abstract
This work formulates a relatively simple isotropic local Overlay J2-Viscoelastic-Viscoplastic-Viscodamage constitutive model (O-J2-VVV) which encompasses the merits [...]
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Viscoelasticity and rate-dependent continuum damage
M. Cervera

Monograph CIMNE (2003). M79
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A mixed Finite Element formulation for incompressibility using linear displacement and pressure interpolations
D. Christ, M. Cervera, M. Chiumenti, C. Agelet

Monograph CIMNE (2003). M77

Abstract
In this work shall be presented a stabilized finite element method to deal with incompressibility in solid mechanics. A mixed formulation involving pressure and displacement fields is used and a continuous linear interpolation is considered for both fields. To overcome the Ladyzhenskaya-Babuska-Brezzi condition, a stabilization technique based on the orthogonal sub-grid scale method is introduced. The main advantage of the method is the possibility of using linear triangular finite elements, which are easy to generate for real industrial applications. Results are compared with several improved formulations, as the enhanced assumed strain method (EAS) and the Q1P0-formulation, in nearly incompressible problems and in the context of linear elasticity and J2-plasticity.
Abstract
In this work shall be presented a stabilized finite element method to deal with incompressibility in solid mechanics. A mixed formulation involving pressure and displacement [...]
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Simulation of temperature and stress during and after RCC dams construction
M. Cervera, M. Goltz

Monograph CIMNE (2003). M76

Abstract
The aim of this monograph is to verify the prediction of temperature and stress evolution of the finite element program COMET including the constitutive model using 1-D model. It includes the analysis of the Rialb RCC dam during and after its construction.
Abstract
The aim of this monograph is to verify the prediction of temperature and stress evolution of the finite element program COMET including the constitutive model using 1-D model. [...]
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Simulación numérica del comportamiento mecánico de los materiales compuestos
S. Oller

Monograph CIMNE (2003). M74

Abstract
El presente trabajo resume la tarea de investigación llevada a cabo por el autor en el área de los materiales compuestos durante los últimos doce años (desde 1990). El mismo refleja la actividad realizada personalmente, junto a otros investigadores y también a través de los estudiantes de fin de carrera y doctorado que he dirigido en esta línea de trabajo. Los temas que aquí se incluyen están orientados fundamentalmente a la modelización constitutiva y evaluación de estructuras construidas en materiales compuestos. Los mismos han sido y muchos de ellos siguen siendo originales, por lo que no representan una mera continuidad de las corrientes investigadoras que estaban en desarrollo en cada momento.
Abstract
El presente trabajo resume la tarea de investigación llevada a cabo por el autor en el área de los materiales compuestos durante los últimos doce [...]
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Mecánica de daño continuo
B. Luccioni

Monograph CIMNE (2003). M71

Abstract
En esta monografía se intenta presentar un marco teórico general que permita analizar la gran cantidad de modelos de daño continuo existentes, no sólo desde el punto de vista de su formulación sino también teniendo en cuenta su capacidad para reproducir las evidencias experimentales correspondientes a un amplio rango de materiales y su implementación numérica en códigos de elementos finitos. La monografía se restringe al tratamiento del daño en pequeñas deformaciones y dentro del marco de la Mecánica de Medios Continuos.
Abstract
En esta monografía se intenta presentar un marco teórico general que permita analizar la gran cantidad de modelos de daño continuo existentes, no sólo [...]
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Topics on failure mechanics
J. Oliver

Monograph CIMNE (2002). M68
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Desarrollo sostenible del cemento y del hormigón
R. Gettu

Monograph CIMNE (2002). M67

Abstract
Esta monografía contiene algunas de las comunicaciones presentadas al Seminario Internacional CANMET/ACI/UPC sobre Desarrollo Sostenible del Cemento y del Hormigón celebrado los días 4 y 5 de noviembre de 2002 en Barcelona, España.
Abstract
Esta monografía contiene algunas de las comunicaciones presentadas al Seminario Internacional CANMET/ACI/UPC sobre Desarrollo Sostenible del Cemento y del Hormigón [...]
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Dinámica no-lineal
S. Oller

Monograph CIMNE (2002). M63

Abstract
Esta monografía trata la “dinámica no-lineal” de los sistemas estructurales. Existen diversos enfoques para esta materia y por ello intento que este trabajo aporte un punto de vista más al estudio dinámico no-lineal. La motivación para escribir estas páginas se basa en la necesidad de contar con un material de estudio para la asignatura de “Dinámica no-lineal” que dicto en doctorado del departamento de “Resistencia de Materiales y Estructuras en la Ingeniería” de la Universidad Politécnica de Cataluña. Espero que estas notas ayuden a la mejor comprensión de la dinámica e incentiven a lector a una mayor profundización.
Abstract
Esta monografía trata la “dinámica no-lineal” de los sistemas estructurales. Existen diversos enfoques para esta materia y por ello intento que [...]
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On the strong discontinuity approach in finite deformation settings. Theoretical aspects and numerical simulation
J. Oliver, A. Huespe, D. Pulido, E. Samaniego

Monograph CIMNE (2001). M62

Abstract
Taking the strong discontinuity approach as a framework for modeling displacement discontinuities and strain localization phenomena, this Part 1 extends previous results of the authors, for infinitesimal strain settings, to finite deformation scenarios. By means of the strong discontinuity analysis, and for both damage and elastoplasticity continuum (stress-strain) constitutive models, projected discrete (tractions-displacement jumps) constitutive models are derived, together with the strong discontinuity conditions that restrict the stress states at the discontinuous regime. Also a variable bandwidth model, to automatically induce those strong discontinuity conditions, and a discontinuous bifurcation procedure, to determine the initiation and propagation of the discontinuity, are briefly sketched. Numerical simulation issues are tackled in Part 2 of the work.
Abstract
Taking the strong discontinuity approach as a framework for modeling displacement discontinuities and strain localization phenomena, this Part 1 extends previous results of [...]
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Un método de elementos finitos para análisis hidrodinámico de estructuras navales
J. García-Espinosa, E. Oñate, H. Sierra

Monograph CIMNE (2000). M59

Abstract
En este trabajo se presenta una metodología basada en el método de los elementos finitos para el análisis de problemas de flujo incompresible en fluidodinámica naval. Esta metodología se basa en la obtención de unas nuevas ecuaciones diferenciales, basadas en criterios discretos, alternativas a las tradicionales ecuaciones de Navier-Stokes. El punto más novedoso del presente trabajo es la aplicación del método de análisis de flujo incomprensible mencionado a problemas navales.
Abstract
En este trabajo se presenta una metodología basada en el método de los elementos finitos para el análisis de problemas de flujo incompresible en fluidodinámica [...]
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Nuevos elementos finitos para el anaálisis dinámico elastoplástico no lineal de estructuras laminares
P. Cendonya, E. Oñate, J. Miquel

Monograph CIMNE (1997). M36

Abstract
Los objetivos de este trabajo se enmarcan en el análisis de estructuras laminares delgadas sometidas a un régimen dinámico de cargas, que dan origen a grandes cambios de forma sobre la estructura. Se consideran dos nuevas formulaciones de elementos finitos de lámica delgada, siendo una de ellas una nueva formulación que solo considera los desplazamientos de la superficie media del elemento como variables cinemáticas, independizándose de los grados rotacionales de libertad.
Abstract
Los objetivos de este trabajo se enmarcan en el análisis de estructuras laminares delgadas sometidas a un régimen dinámico de cargas, que dan origen a [...]
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El método de desplazamiento crítico para la predicción de puntos límite y de bifurcación en estructuras
W. Matias, E. Oñate

Monograph CIMNE (1997). M35

Abstract
Se presenta la descripción Lagrangiana Generalizada para el análisis estático de sólidos con no linealidad geométrica. Se describen las relaciones incrementales básicas de la cinemática, de la estática y del modelo constitutivo. Se obtiene la forma incremental completa de las ecuaciones de equilibrio no lineales a través del principio de los trabajos visuales. La discretización de dichas ecuaciones por el método de los elementos finitos conduce a la obtención de una expresión paramétrica general y no simétrica de la matriz de rigidez secante incremental. Se obtienen formas simétricas de dicha matriz asignando determinados valores a los parámetros. A partir de la matriz de rigidez secante incremental se deduce, de forma directa, la clásica expresión de la matriz de rigidez tangente empleada en problemas no lineales. Se formula, de manera incremental, la matriz de rigidez secante a través de la descripción Lagrangiana Generalizada, de tal modo que se pueda obtener una relación entre incrementos finitos de fuerzas y desplazamientos. Se discuten las posibilidades de aplicación de la matriz secante en el análisis no lineal de estabilidad, de bifurcación y de carga límite en sistemas estructurales. Se presenta una nueva técnica de predicción de puntos críticos para el análisis de inestabilidad estructural. Este método se basa en la determinación de un campo de desplazamiento crítico que aproxima el modo de bifurcación o el modo de deformación crítico del sistema estructural. Se determinan estos desplazamientos críticos imponiendo la condición de singularidad en una expresión aproximada de la matriz de rigidez tangente en el punto crítico. La carga crítica se obtiene a posteriori, de modo directo, utilizando la relación secante entre carga y desplazamiento. Se detalla este procedimiento y las formas explícitas de las matrices secante y tangente para elementos de barra y de sólido en dos y tres dimensiones. Se muestra la eficiencia y la buena aproximación de los resultados en la simulación numérica de varios ejemplos.
Abstract
Se presenta la descripción Lagrangiana Generalizada para el análisis estático de sólidos con no linealidad geométrica. Se describen las [...]
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A contribution to adaptive numerical solution of compressible flow problems
T. Fischer, E. Oñate

Monograph CIMNE (1996). M34

Abstract
The monograph presents recent developments on the solution of high speed compressible flow problems using finite element and finite point (meshless) methods with adaptive refinement, techniques. This work treats two of the main problems of today's problems related to computational fluid dynamics. One problem dealt with is the assured accuracry of a numerical model, at least for the problems which are presented. The other problem which is addressed is the vast amount of time spent in generating (or regenerating) a mes in the design process.
Abstract
The monograph presents recent developments on the solution of high speed compressible flow problems using finite element and finite point (meshless) methods with adaptive [...]
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Current trends in qualitative reasoning and applications
N. Piera

Monograph CIMNE (1995). M33

Abstract
In June 1994 the ARCA group was founded in order to enhance communication between Spanish professionals either directly on indirectly related to Qualitative Reasoning. Thus we are talking about a new-born group which tries to follow mainly the working pattern of the French QR group, established in 1987 and closely partner of ARCA, both in research and organization matters. Our group maintains also important relationship with other European clusters and is a integrated in the now in progress European QR Network. ARCA is structured around five research lines; the members of each one contact each other on a personal and non programmed basis, but two general meetings a year are scheduled so as to, in the one hand letting every “ARCher” learn about every other’s activities and, on the other hand, starting up projects involving the whole group.
Abstract
In June 1994 the ARCA group was founded in order to enhance communication between Spanish professionals either directly on indirectly related to Qualitative Reasoning. Thus [...]
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Technology transfer of the new trends in concrete
R. Gettu, A. Aguado, S. Shah

Monograph CIMNE (1995). M32

Abstract
The international RILEM Workshop on Technology Transfer of the New Trends in Concrete (ConTech’94) was held at the Universitat Politècnica de Catalunya (UPC). It was organized by the UPC, the International Center for Numerical Methods in Engineering (CIMNE, Barcelona), and the NSF Center for the Science & Technology of Advanced Cement-Based Materials (ACBM, Northwestern University, Evanston,USA). ConTech’94 was sponsored by the International Union of the Testing and Research Laboratories for Materials and Structures (RILEM), the Commission of the European Communities, the Centro i Desenvolupament Empresarial de Generalitat de Catalunya (CIDEM, Barcelona). The workshop had to two primary objectives. First, to discuss the incorporation of recent developments and research results in the concrete technology for the present and the future. Secondly, to help bridge the gaps between research and practice, and between more and less developed sectors in the field of concrete. 100 participants attended the workshop, 88 of whom were from the European Union (including 11 young researchers whose participation was partially funded by the European Commission). The official language of the workshop was English, and simultaneous translation between Spanish and English was provided. In all, 23 lectures were presented by experts form Europe, America and Japan, on topics covering the important aspects of concrete technology. The papers corresponding to the lectures are included in a book published by E & FN SPON.
Abstract
The international RILEM Workshop on Technology Transfer of the New Trends in Concrete (ConTech’94) was held at the Universitat Politècnica de Catalunya (UPC). [...]
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Nonlinear finite element techniques using and object-oriented code
A. Villa, A. Rodríguez, A. Huerta

Monograph CIMNE (1995). M31

Abstract
When treating nonlinear problems with the Finite Element formulation, the need to solve nonlinear sets of equations arises. Classically, those nonlinear sets of equations were solved by performing an incremental / iterative analysis with a full Newton-Raphson method. Today, one can chose from a wide range of methods. The modifications to the original fNR method use tangent stiffness matrices, which are updated at most once per increment. Quasi-Newton methods use secant matrices instead of tangent matrices. Secant-Newton methods are simplifications of the Quasi-Newton. This work deals, in particular, with the implementation of these methods in an object-oriented code and with the comparison between them on several tests. The expected behavior of the methods is observed from the results. Also, an acceleration line-search technique is implemented to improve the results supplied by the previous methods.
Abstract
When treating nonlinear problems with the Finite Element formulation, the need to solve nonlinear sets of equations arises. Classically, those nonlinear sets of equations [...]
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Evaluation of existing highway bridge systems
M. Ghosn, J. Casas

Monograph CIMNE (1996). M30

Abstract
Evaluation, repair and rehabilitation of bridges are increasingly important topic in current efforts to deal with the deteriorating infrastructure of developed countries. In fact, after several years of large scale construction projects to build new highway networks, the number of existing bridges is so large that current administrations need to invest increasingly large amounts of funds on the maintenance, diagnostic and repair of these bridges
Abstract
Evaluation, repair and rehabilitation of bridges are increasingly important topic in current efforts to deal with the deteriorating infrastructure of developed countries. [...]
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Comportamiento térmico de presas de hormigón en servicio
L. Agulló, A. Aguado, E. Mirambell

Monograph CIMNE (1995). M29

Abstract
Este trabajo se enmarca en el ámbito de las presas de hormigón en fase de explotación y, dentro de este ámbito, se centra en el análisis de la respuesta térmica de la presa frente a la actuación de la acción térmica ambiental.
Abstract
Este trabajo se enmarca en el ámbito de las presas de hormigón en fase de explotación y, dentro de este ámbito, se centra en el análisis [...]
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Retention of Mechanical Properties After Water Immersion for Glass-Fibre Polymer Composite Laminates with Thermoset & Thermoplastic Infusible Resins
N. Nash, C. Bachour, I. Manolakis, A. Comer

Open Access Repository of the FIBRESHIP project (2019). 2

Abstract
In this work, we conducted an extensive comparative study of the water absorption behavior and retention of mechanical properties of a group of GRP composite laminates manufactured with a range of infusible thermosetting and thermoplastics resins. All laminates were manufactured by Vacuum-Assisted Resin Transfer Moulding (VARTM; the most relevant manufacturing technique in shipbuilding) with a range of state-of-the-art thermosetting resins (Urethane acrylate Crestapol 1210, Epoxy SR1125, Bio-epoxy Supersap CLR, Phenolic Cellobond J2027X) and a novel infusible acrylic thermoplastic resin (Acrylic Elium 150). The reinforcement of choice for each laminate was a unidirectional glass fabric of 996 gsm. Sample preparation for water immersion studies was according to ASTM D5229. This study was part of a comprehensive down-selection of commercially available resins in terms of their suitability for shipbuilding applications, as part of the EU H2020 project FIBRESHIP2 . A selection of relevant properties of the laminates with different resin systems is presented in this paper including fibre volume fraction, apparent interlaminar shear strength (dry and wet condition), flexural strength (dry and wet condition) and flexural modulus (dry and wet condition).
Abstract
In this work, we conducted an extensive comparative study of the water absorption behavior and retention of mechanical properties of a group of GRP composite laminates manufactured [...]
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Thermoplastic infusible resin systems: candidates for the marine sector?
N. Nash, C. Sirerol, I. Manolakis, A. Comer

ECCM18 - 18th European Conference on Composite Materials, Athens (Greece)

Abstract
This work investigated the feasibility of the use of a novel infusible thermoplastic resin (Elium 150 from Arkema) for composite laminate manufacture by resin infusion methods and possible application in the shipbuilding sector. We compared the properties of Elium glass-fibre laminates with those of laminates infused with state-of-the-art thermosetting epoxy and urethane acrylate resins. The Elium laminates matched the mechanical performance (flexure and interlaminar shear strength) of the epoxy and surpassed that of the urethane acrylate counterpart. However, the mechanical performance of the Elium laminates after immersion in water at 35 oC for 28 days deteriorated compared to urethane acrylate, but was comparable in flexural properties to that of the epoxy. The combination of superior mechanical performance coupled with acceptable environmental resistance and comparable composite laminate manufacturing conditions makes the infusible thermoplastic a possible future candidate matrix over commercial thermosetting resin options.
Abstract
This work investigated the feasibility of the use of a novel infusible thermoplastic resin (Elium 150 from Arkema) for composite laminate manufacture by resin infusion methods [...]
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Modelling strong discontinuities in solid mechanics via strain softening constitutive equations
J. Oliver

Monograph CIMNE (1995). M28

Abstract
This part addresses some fundamental aspects about the use of standard constitutive equations to model strong discontinuities (cracks, shear bands, slip lines, etc.) in solid mechanics analyzes. The so called strong discontinuity analysis is introduced as a basic tool to derive a general framework, in which different families of constitutive equations can be inscribed, then allowing to extract relevant aspects for the intended analysis. In particular, a ling between continuum ad discrete approaches to the strain localization phenomena is obtained. Applications to standard continuum damage and elasto-plastic constitutive equations are presented. Relevant aspects to be considered in the numerical simulation of the problem are alo presented.
Abstract
This part addresses some fundamental aspects about the use of standard constitutive equations to model strong discontinuities (cracks, shear bands, slip lines, etc.) in solid [...]
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Utilización de la información histórica en el análisis regional de las avenidas.
F. Francés

Monograph CIMNE (1995). M27
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Bio-based epoxy resin systems as potential alternatives to petroleum based epoxy matrices in marine fibre-reinforced polymer composites
N. Nash, L. Egan, C. Bachour, I. Manolakis, A. Comer

Open Access Repository of the FIBRESHIP project (2019). 1

Abstract
Fibre-reinforced polymers (FRP) are extensively used in the marine industry for the manufacture of lightweight hull structures for vessels up to 50m in length, and for secondary structures and components in larger vessels. The main benefits resulting in the application of FRP in shipbuilding include: significant weight reduction resulting in substantial fuel saving, increase in cargo capacity and subsequent reduction of greenhouse gas emissions, improved life cycle performance and reduced maintenance costs due to corrosion resistance. As the use of thermoset polymers in shipbuilding increases, so too does the interest in finding suitable alternatives to the use of petroleum-based raw materials. Much work has been published on bio-based epoxy resin systems from natural raw materials, such as vegetable oils, however, the mechanical performance of the bio-based resin systems in comparison to equivalent petroleum-based systems is not widely documented. This research focusses on the comparison of petroleum-based and bio-based two-part commercial epoxy resin systems to manufacture glass fibre reinforced polymers (GFRP) for marine applications. Laminates were manufactured using the Vacuum Assisted Resin Transfer Moulding (VARTM) manufacturing process. Specimens were mechanically characterised in order to evaluate fibre volume fraction, density, apparent inter-laminar shear strength, flexural modulus and strength. The effect of water ingress on the mechanical properties of laminates was also studied by soaking samples in water at 35°C for 28 days. Specimen quality and fracture surfaces were assessed using optical and scanning electron microscopy. Initial results have shown that the average apparent inter-laminar shear strength of the petroleum-based samples was almost identical to the bio-based samples (within 1%), while the flexural strength and modulus of the petroleum-based samples was only 6% and 7% higher than the bio-based samples. Despite the comparatively good mechanical performance of the bio-based laminate, the high viscosity of the resin resulted in higher infusion temperatures and longer infusion times than for the petroleum-based epoxy.
Abstract
Fibre-reinforced polymers (FRP) are extensively used in the marine industry for the manufacture of lightweight hull structures for vessels up to 50m in length, and for secondary [...]
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Variability in uncertainty cost for micro-Wind Energy Generation (WEG)
L. Avellaneda, J. Monsalve, S. Rivera

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (3), 39

Abstract
Faced with the problem of wind speed in generation and the difficulty that this entails in the economic future of electric power, mathematical formulations (functions), called uncertainty costs, have been developed. The term is used in a model composed of two parts, an implication of penalization costs for overestimation and the other due to the underestimation of a programmed power. Through analytical mathematics and Monte Carlo simulations, we have found the expected value of the costs of uncertainty, the stability of primary resources through the distribution of probability. However, the results can not be evaluated accurately from an analytical point of view, without taking into account the variability around the average value. In this article we calculate the analytical function of the variance, we understand as a measure of dispersion of the expected values of uncertainty costs for the specific case of wind operators; Likewise, this formulation has been validated through Monte Carlo simulations. The function found is used to observe the dispersion of the data around its expected average value, by applying the standard deviation.
Abstract
Faced with the problem of wind speed in generation and the difficulty that this entails in the economic future of electric power, mathematical formulations (functions), called [...]
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Study of the influence of protuberances in the trailing edge of airfoils and determination of their aerodynamic efficiency through CFD using Ansys Fluent
A. González, J. Hinojosa

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (3), 36

Abstract
In the present research, the effect of incorporating protuberances in the leading edge to the aerofoil NACA-0012 was studied. For the simulations, two profiles were designed: parametric profile (NACA 0012) and modified profile (0012-MOD), with help of CAD Program Inventor Professional 2016. The 0012-MOD profile incorporates modifications in the leading edge, whose inspiration comes from malformations present on the flippers of the humpback whale (Megaptera novaeangliae). The computational simulations were performed in Ansys Fluent, using the turbulent viscosity model k-ε realizable, with SIMPLE calculation algorithm. The study fluid is air in the incompressible range with Ma: 0.11. To obtain the lift and drag curves for both profiles, they were simulated for angles of attack α: between 0° and 40°, this way it will be possible to compare the profiles and determine their aerodynamic behaviour. In the present research, the effect of incorporating protuberances in the leading edge to the aerofoil NACA-0012 was studied. For the simulations, two profiles were designed: parametric profile (NACA 0012) and modified profile (0012-MOD), with help of CAD Program Inventor Professional 2016. The 0012-MOD profile incorporates modifications in the leading edge, whose inspiration comes from malformations present on the flippers of the humpback whale (Megaptera novaeangliae). The computational simulations were performed in Ansys Fluent, using the turbulent viscosity model k-ε realizable, with SIMPLE calculation algorithm. The study fluid is air in the incompressible range with Ma: 0.11. To obtain the lift and drag curves for both profiles, they were simulated for angles of attack α: between 0° and 40°, this way it will be possible to compare the profiles and determine their aerodynamic behaviour.
Abstract
In the present research, the effect of incorporating protuberances in the leading edge to the aerofoil NACA-0012 was studied. For the simulations, two profiles were designed: [...]
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Real-time micro-modelling of city evacuations
R. Löhner, E. Haug, C. Zinggerling, E. Oñate

Comp. Part. Mech (2018). Vol. 5 (1), pp. 71-86

Abstract
A methodology to integrate geographical information system (GIS) data with large-scale pedestrian simulations has been developed. Advances in automatic data acquisition and archiving from GIS databases, automatic input for pedestrian simulations, as well as scalable pedestrian simulation tools have made it possible to simulate pedestrians at the individual level for complete cities in real time. An example that simulates the evacuation of the city of Barcelona demonstrates that this is now possible. This is the first step towards a fully integrated crowd prediction and management tool that takes into account not only data gathered in real time from cameras, cell phones or other sensors, but also merges these with advanced simulation tools to predict the future state of the crowd.
Abstract
A methodology to integrate geographical information system (GIS) data with large-scale pedestrian simulations has been developed. Advances in automatic data acquisition and [...]
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Virtual modeling of polycrystalline structures of materials using particle packing algorithms and Laguerre cells
C. Recarey Morfa, M. Farias, I. Pérez, E. Oñate

Comp. Part. Mech (2018). Vol. 5 (2), pp. 213-226

Abstract
The influence of the microstructural heterogeneities is an important topic in the study of materials. In the context of computational mechanics, it is therefore necessary to generate virtual materials that are statistically equivalent to the microstructure under study, and to connect that geometrical description to the different numerical methods. Herein, the authors present a procedure to model continuous solid polycrystalline materials, such as rocks and metals, preserving their representative statistical grain size distribution. The first phase of the procedure consists of segmenting an image of the material into adjacent polyhedral grains representing the individual crystals. This segmentation allows estimating the grain size distribution, which is used as the input for an advancing front sphere packing algorithm. Finally, Laguerre diagrams are calculated from the obtained sphere packings. The centers of the spheres give the centers of the Laguerre cells, and their radii determine the cells’ weights. The cell sizes in the obtained Laguerre diagrams have a distribution similar to that of the grains obtained from the image segmentation. That is why those diagrams are a convenient model of the original crystalline structure. The above-outlined procedure has been used to model real polycrystalline metallic materials. The main difference with previously existing methods lies in the use of a better particle packing algorithm.
Abstract
The influence of the microstructural heterogeneities is an important topic in the study of materials. In the context of computational mechanics, it is therefore necessary [...]
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Systemic characterization and evaluation of particle packings as initial sets for discrete element simulations
C. Recarey Morfa, L. Cortés, M. Farias, I. Pérez, R. Valera, E. Oñate

Comp. Part. Mech (2018). Vol. 5 (3), pp. 319-334

Abstract
A methodology that comprises several characterization properties for particle packings is proposed in this paper. The methodology takes into account factors such as dimension and shape of particles, space occupation, homogeneity, connectivity and isotropy, among others. This classification and integration of several properties allows to carry out a characterization process to systemically evaluate the particle packings in order to guarantee the quality of the initial meshes in discrete element simulations, in both the micro- and the macroscales. Several new properties were created, and improvements in existing ones are presented. Properties from other disciplines were adapted to be used in the evaluation of particle systems. The methodology allows to easily characterize media at the level of the microscale (continuous geometries—steels, rocks microstructures, etc., and discrete geometries) and the macroscale. A global, systemic and integral system for characterizing and evaluating particle sets, based on fuzzy logic, is presented. Such system allows researchers to have a unique evaluation criterion based on the aim of their research. Examples of applications are shown.
Abstract
A methodology that comprises several characterization properties for particle packings is proposed in this paper. The methodology takes into account factors such as dimension [...]
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General advancing front packing algorithm for the discrete element method
C. Recarey Morfa, I. Pérez, M. Farías, E. Oñate, R. Valera, H. Casañas

Comp. Part. Mech (2018). Vol. 5, pp 13–33

Abstract
A generic formulation of a new method for packing particles is presented. It is based on a constructive advancing front method, and uses Monte Carlo techniques for the generation of particle dimensions. The method can be used to obtain virtual dense packings of particles with several geometrical shapes. It employs continuous, discrete, and empirical statistical distributions in order to generate the dimensions of particles. The packing algorithm is very flexible and allows alternatives for: 1—the direction of the advancing front (inwards or outwards), 2—the selection of the local advancing front, 3—the method for placing a mobile particle in contact with others, and 4—the overlap checks. The algorithm also allows obtaining highly porous media when it is slightly modified. The use of the algorithm to generate real particle packings from grain size distribution curves, in order to carry out engineering applications, is illustrated. Finally, basic applications of the algorithm, which prove its effectiveness in the generation of a large number of particles, are carried out.
Abstract
A generic formulation of a new method for packing particles is presented. It is based on a constructive advancing front method, and uses Monte Carlo techniques for the generation [...]
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Computation of the stabilization parameter for the finite element solution of advective–diffusive problems
E. Oñate, J. García-Espinosa, S. Idelsohn

Int. J. for Num. Meths. in Fluids (1997). Vol. 25, pp. 1387-1407

Abstract
In a previous paper a general procedure for deriving stabilized finite element schemes for advective type problems based on invoking higher order balance laws over finite size domains was presented. This provides an expression for the element stabilization parameter in terms of the solution residual and its first derivatives in a kind of iterative or adaptative manner. Details of the application of this procedure to 1D and 2D advective- diffusive problems are given. Some examples of applications showing the potential of the new approach are presented.
Abstract
In a previous paper a general procedure for deriving stabilized finite element schemes for advective type problems based on invoking higher order balance laws over finite [...]
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A Comparison of two objective stress rates in object-oriented codes
A. Rodríguez-Ferran, A. Huerta

Monograph CIMNE (1994). M26

Abstract
An object-oriented code, CASTEM2000, has provided the framework for algorithmic development and numerical testing. In these codes, information is stored and manipulated as objects which represent the entitiesrelevant to a finite element method computation.
Abstract
An object-oriented code, CASTEM2000, has provided the framework for algorithmic development and numerical testing. In these codes, information is stored and manipulated as [...]
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A rate dependent plastic-damage constitutive model for large scale computational in concrete structures
R. Faria, J. Oliver

Monograph CIMNE (1993). M17
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Integration methodology of different softwares for constrained tubular truss size optimization problems
C. Lage, F. Neves, M. Freitas

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (3), 42

Abstract
Practical size structural optimization problems can involve a large number of variables and constraints that meet regulatory requirements for safety and structural performance. Most optimization problems tend to find the minimum value of the objective function within a feasible set that satisfies the constraints. Among evolutionary computation techniques, genetic algorithms (GAs) have been successfully used for the optimization of structures, including lattice systems. This article proposes an automated interactive methodology for the optimization of structures based on the integration of two commercial programs: Ansys and Matlab. The developed script uses the Finite Element Method for the analysis of the structure, together with the Genetic Algorithms for the optimization. The objective of the article is to evaluate the applicability, precision and efficiency of the proposed methodology. Two numerical examples of trusses were solved with the proposed methodology, classic truss of the literature and truss with normative restrictions. The results show that the methodology is adequate for the solution of size structural optimization problems with a good precision of the results.
Abstract
Practical size structural optimization problems can involve a large number of variables and constraints that meet regulatory requirements for safety and structural performance. [...]
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Análisis de problemas de choque e impacto entre sólidos deformables por el Método de los Elementos Finitos.
J. Miquel, E. Oñate, C. Garino, S. Botello, F. Flores, J. Rojek

Monograph CIMNE (1994). M25

Abstract
El trabajo que se expone ha hecho uso de los últimos avances en mecánica computacional, métodos numéricos, visualización y algoritmos de cálculo para obtener un programa de ordenador para simulación de problemas de choque e impacto de interés práctico para una amplia variedad de sectores industriales. En particular, el objetivo del proyecto SIMPACT ha sido el desarrollo de un paquete de software para análisis de problemas de dinámica rápida y análisis no lineal procesable en una amplia variedad de ordenadores, con aplicación a choques de vehículos, impacto en estructuras aeroespaciales, defensa y problemas de conformado, entre otros.
Abstract
El trabajo que se expone ha hecho uso de los últimos avances en mecánica computacional, métodos numéricos, visualización y algoritmos de [...]
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Estructuras de edificación con aislaminto antisísmico
L. Jané, A. Barbat

Monograph CIMNE (1992). M13
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Estimación y corrección del error en el análisis estructural por el MEF
G. Bugeda

Monograph CIMNE (1991). M9

Abstract
En los últimos años se han desarrollado diversas técnicas para resolver el problema de la estimación y la corrección del error. De hecho, la mayoría de los avances que se han realizado dentro del campo de los elementos finitos se pueden entender como formas distingas de minimizar el error existente en las soluciones. En esta monografía se hablará de dos técnicas distintas para la corrección de errores: Técnicas de refinamiento y técnicas de remallado.
Abstract
En los últimos años se han desarrollado diversas técnicas para resolver el problema de la estimación y la corrección del error. De hecho, [...]
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Modelización numérica de materiales friccionales
S. Oller

Monograph CIMNE (1991). M10

Abstract
La presente monografía trata el problema del comportamiento de los materiales friccionales, especialmente del hormigón, más allá de su límite elástico. Estudia los problemas de aplastamiento y fractura y describe un modelo constitutivo amplio que permite una muy adecuada simulación de estos fenómenos.
Abstract
La presente monografía trata el problema del comportamiento de los materiales friccionales, especialmente del hormigón, más allá de su límite [...]
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A Finite Element formulation for the numerical solution of the convection-diffusion equation
R. Codina

Monograph CIMNE (1993). M14

Abstract
In this work we present several finite element techniques to solve the convection-diffusion equation when the Péclet number is high, tha is, when diffusion is very small. The basic finite element formulation employed here is the Streamline-Upwind-Petrov-Galerkin (SUPG). A thorough description of this approach is presented in Chapter 1. Chapter 2 deals with the application of the generalized trapezoidal rule to advance in time for the transient equation. A complete stability and accuracy analysis is performed for the explicit Euler scheme, both using linear and quadratic finite elements. Chapter 3 is concerned with the problem of removing the localized oscillations that remain about abrupt layers of the solution.
Abstract
In this work we present several finite element techniques to solve the convection-diffusion equation when the Péclet number is high, tha is, when diffusion is very [...]
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Mechanics of a continuum medium. Vol. III
A. Fusco

Monograph CIMNE (1993). M20

Abstract
This work presents the fundamental assumptions and the successive mathematical developments which allow to establish the complete field equations of a continuum. The aim is to be sufficiently general and self-content using, however, mathematical procedures which can be always understook by an engineer with a common background of Linear Algebra and elementary Differential Calculus.
Abstract
This work presents the fundamental assumptions and the successive mathematical developments which allow to establish the complete field equations of a continuum. The aim is [...]
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A Finite Element formulation for viscous incompressible flows
R. Codina

Monograph CIMNE (1993). M16
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Modelado de la fisuración en estructuras de hormigón
J. Oliver

Monograph CIMNE (1993). M15

Abstract
En este trabajo, se presenta una perspectiva general de los modelos de fisuración existentes y de algunas aportaciones de la línea de investigación que se desarrollan, tanto en el dominio de la formulación teórica de dichos modelos como de su aplicación práctica.
Abstract
En este trabajo, se presenta una perspectiva general de los modelos de fisuración existentes y de algunas aportaciones de la línea de investigación que [...]
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Lectures on nonlinear finite element analysis of concrete shells
E. Oñate

Monograph CIMNE (1991). M7

Abstract
This monograph presents 4 lectures on non linear analysis of concrete shells by the finite element method. The lectures were prepared by the author for the course on "Non linear analysis of shells by finite elements" held at the International Center for Mechanics Sciences in Udine, Italy on June 24-28th 1991. The content of the lectures presents an overview of the different aspects involved in the analysis of concrete shells by finite elements. Thus, Lecture 1 introdeuces the basic concepts of the analysis of reinforced concrete shell structures using flat shell and curved degenerated layered shell finite elements. Both the geometric and kinematic assumptions are described in detail together with the respective finite element formulation and the numerical algorithm for non linear elasto-plastic analysis including the effect of moderately large displacements. Lecture 2 presents an overview of the constitutive behaviour of concrete and steel in a form suitable for numerical computations using the finite element models described in previous lecture. The reinforcing steel bars are modelled with a simple elasto-plastic model. Hovewer, two conceptualy different concrete models are presented. The first model is based on elasto-plastic theory to describe the compressive behaviour of concrete, whereas a linear orthotropic elasto-brittle model is used for modelling the cracking behaviour under tensile conditions. This ``elasto-platic-brittle model has been extensively used by Owen and Figueiras and most of the concepts presented emanate from reference [18] of this chapter. The second model is based on the assumptions that both the tensile and compressive behaviour of concrete can be treated under the unified framework of elasto-plasticity theory. This model termed ``plastic-damage model has ben proposed by Lubliner, Oller, Oliver and O\~nate in different publications which main concepts are summarized in the lecture (see refs. [33-38] of this chapter). In Lecture 3 the basic finite element formulation for the analysis of stiffened concrete shells via the use of eccentric beams is described. Finally, in Lecture 4 some examples of applications of the finite element formulations presented to the non-linear analysis of different reinforced concrete shell structures analyzed by different authors are described. Examples included range from the analysis of plain and pre-stressed concrete deep beams, to more sophisticated shell type structures including the nonlinear behaviour of a composite steel-concrete girder bridge and a cryogenic concrete liquid gas tank under severe thermal conditions. This monograph has been written exclusively with didactic purposes. Most of the ideas included in the text have been extracted from research publications by the author and many others. The interested reader will be able to find details on the different subjects treated in the many references included at the end of each chapter.
Abstract
This monograph presents 4 lectures on non linear analysis of concrete shells by the finite element method. The lectures were prepared by the author for the course on "Non [...]
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Análisis dinámico de presas
J. Miquel, E. Oñate, J. Buil, E. Herrero

Monograph CIMNE (1991). M5

Abstract
Se desarrolla en este trabajo un estudio numérico-experimental acerca del comportamiento dinámico de las presas bóvedas considerando su interacción con el agua del embalse. Para ello, se ha realizado un análisis de los factores que inciden más directamente en el comportamiento dinámico de tales tipos de estructuras. Dicho análisis se realiza mediante e lmétodo de los elementos finitos, estudiando distintas alternativas de formulación. Asimismo, se ha realizado un esayo a escala real de una presa bóveda existente, mediante una serie de explosiones y midiendo la respuesta obtenida.
Abstract
Se desarrolla en este trabajo un estudio numérico-experimental acerca del comportamiento dinámico de las presas bóvedas considerando su interacción [...]
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Simulación Numérica de Patologías en Presas de Hormigón
M. Cervera, J. Oliver, M. Galindo

Monograph CIMNE (1991). M4
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A stabilized mixed implicit Material Point Method for non-linear incompressible solid mechanics
I. Iaconeta, A. LARESE, R. Rossi, E. Oñate

Computational Mechanics (2019). Vol. 63 (6), pp. 1243–1260

Abstract
In this work a stabilized mixed formulation for the solution of non-linear solid mechanics problems in nearly-incompressible conditions is presented. In order to deal with high material deformation, an implicit Material Point Method is chosen. Such choice allows avoiding the classical limitations of the Finite Element Method, e.g., element tangling and extreme mesh distortion. The proposed mixed formulation, with displacement and pressure as primary variables, is tested through classical benchmarks in solid and geo-mechanics where a Neo-Hookean, a J2 and a Mohr-Coulomb plastic law are employed. Further, the stabilized mixed formulation is compared with a displacement-based formulation to demonstrate how the proposed approach gets better results in terms of accuracy, not only when incompressible materials are simulated, but also in the case of compressible ones.
Abstract
In this work a stabilized mixed formulation for the solution of non-linear solid mechanics problems in nearly-incompressible conditions is presented. In order to deal with [...]
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Determining the micro film of hexyl alcohol in laminar condition on a rotating drum
C. Trang

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (2), 28

Abstract
In this research, the free surface of micro film of hexyl alcohol on a partially submerged rotating drum has been predicted using CFD (computational fluid dynamics) and compared with experimental data and analytical solution. The trend of has been found very comparable with experimental and analytical solution. A Matlab code was used to model the flow and film dynamics. Computationally it was an unsteady state problem and semi-steady state was achieved. No surfactant was present on the surface. The speed of the moving rotating drum was set a ''rpm''. With the increase of rotating drum, the minimum film thickness increases with ''rpm'' (for \alpha _o = 47^{0} and for \alpha _o = 58^{0}).
Abstract
In this research, the free surface of micro film of hexyl alcohol on a partially submerged rotating drum has been predicted using CFD (computational fluid dynamics) and compared [...]
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Numerical analysis of particulate flows with the finite element method
G. Casas, E. Oñate, R. Rossi

Monograph CIMNE (2018). M181

Abstract
In this work we study the numerical simulation of particle-laden fluids, with an emphasis on Newtonian fluids and spherical, rigid particles. Our general strategy consists in using the discrete element method (DEM) to model the particles and the finite element method (FEM) to discretize the continuous phase, such that the fluid is not resolved around the particles, but rather averaged over them. The effect of the particles on the fluid is taken into account by averaging (filtering) their individual volumes and particle-fluid interaction forces. In the first part of the work we study the Maxey–Riley equation of motion for an isolated particle in a nonuniform flow; the equation used to calculate the trajectory of the DEM particles. In particular, we perform a detailed theoretical study of its range of applicability, reviewing the initial effects of breaking its fundamental hypotheses, such as small Reynolds number, sphericity of the particle, isolation etc. The output of this study is a set of tables containing order-of-magnitude inequalities to assess the validity of the method in practice. The second part of the work deals with the numerical discretization of the MRE and, in particular, the study of different techniques for the treatment of the history-dependent term, which is difficult to calculate efficiently. We provide improvements on an existing method, proposed by van Hinsberg et al. (2011), and demonstrate its accuracy and efficiency in a sequence of tests of increasing complexity. In the final part of the work we give three application examples representative of different regimes that may be encountered in the industry, demonstrating the versatility of our numerical tool. For that, we describe necessary generalizations to the MRE to cover problems outside its range of applicability. Furthermore, we give a detailed account of the stabilized FEM algorithm used to discretize the fluid phase and compare several derivative recovery tools necessary to calculate some of the interphase coupling terms. Finally, we generalize the algorithm to include the backward-coupling effects according to the theory of multicomponent continua, allowing the code to deal with arbitrarily dense flow regimes.
Abstract
In this work we study the numerical simulation of particle-laden fluids, with an emphasis on Newtonian fluids and spherical, rigid particles. Our general strategy consists [...]
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Application of optimization techniques to the determination of modal parameters in civil structures by the identification method
L. VILLA GARCIA

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (3), 45

Abstract
In the present paper, the application of optimization techniques –via FRF– is developed for determining modal parameters by means of the identification method that are exclusively limited to: systems with viscous damping, low levels of damping, and methods that work within the frequency domain. Decomposition techniques are proposed for working with complex magnitudes that allow the real and imaginary parts to be treated separately (which can, in this way, be implemented in commercial optimization programs), even in matrix product operations. The influence of high and low modes is rigorously taken into consideration via the selfsame optimization algorithm. To illustrate this work we have analyzed a structure unique in its slenderness, La Cartuja Bridge (Seville, Spain), which also constitutes a very light structure with very little damping. Its design contributed in its day a new structural framework of complicated geometries through the use of a new material: high yield strength steel.
Abstract
In the present paper, the application of optimization techniques –via FRF– is developed for determining modal parameters by means of the identification method [...]
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Comparison of Wind Loads on Flat and Gabled Roofs calculated with the Colombian Building Code and Numerical Results using CFD
M. OSORIO, L. Cordoba Florez, A. Cruz, J. Marulanda, P. Thomson

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (2), 29

Abstract
The Colombian building code, NSR-10, specifies three methods for estimating wind loads on structures: a) a Simplified Method, b) an Analytical Method and c) Wind Tunnel Testing. The first two of these methods are widely used by structural engineers in Colombia, as wind tunnel testing is comparatively expensive and time consuming, and only mandatory in special cases. Although the Simplified Method is only valid for buildings with regular shaped roofs and overall heights less than 18 m, the Analytical Method can be used for any regular building, regardless of the height. However, when these two methods are used to estimate wind loads for buildings with heights less than 18 m, they often produce very different results and, at times, contradictory values. In this study, Computational Fluids Dynamic (CFD) analyses were performed on flat and gabled roofed building models in order to compare the pressures on the roofs with those calculated using the standard design methods specified by the Colombian building code. The results illustrate the significant differences produced from the Simplified and Analytical methods of the NSR-10 and highlight the need of conducting wind tunnel tests in order to propose a more consistent method for estimating design wind loads in Colombia
Abstract
The Colombian building code, NSR-10, specifies three methods for estimating wind loads on structures: a) a Simplified Method, b) an Analytical Method and c) Wind Tunnel Testing. [...]
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Experimental and numerical fracture tests in concrete. Towards the Virtual Laboratory
F. Zarate, A. Gomez, E. Oñate

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 14

Abstract
This paper describes a computation methodology to evaluate the ultimate strength and fracture of concrete samples and structures and its application to four typical tests of experimental laboratories of strength of materials. The tests results are compared and analysed from the experimental and numerical points of view in order to highlight the need for experimental trials to use the information derived from numerical results and, in turn, to validate that numerical models follow the behaviour and physics that occur in laboratory tests This comparison allows to explain the different mechanisms that occur throughout the experiments.
Abstract
This paper describes a computation methodology to evaluate the ultimate strength and fracture of concrete samples and structures and its application to four typical tests [...]
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Simulation of resistance and deformability of rocks via discrete elements with cemented particles
L. Medina, M. Farias, L. Rasmussen, C. Recarey

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 18

Abstract
The Discrete Element Method (DEM) appears as one of the most attractive methods for understanding general geotechnical problems and specifically the behavior of rocks due to their unique advantages in dealing with fracturing processes. In this work, unconfined compression and indirect tensile tests were performed for a magmatic rock, known as Lac du Bonnet granite, based on a discrete approach using DEM and a specific contact and cementation model between the particles. Concluding, a parametric analysis of the influence of Young's modulus on some macroscopic properties of the rock’s numerical model was carried out, with the objective of generating contributions as to the understanding of the deformability and strength behavior of hard rocks.
Abstract
The Discrete Element Method (DEM) appears as one of the most attractive methods for understanding general geotechnical problems and specifically the behavior of rocks due [...]
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Comparative Analysis of Slender Columns by Approximate Methods
L. ARAUJO

Análise comparativa dos Métodos Aproximados de Dimensionamento de Pilares Esbeltos de Concreto (2018). ARAUJO, L, J.; Dos Santos ; BARBOSA, W. C. S. . ANÁLISE COMPARATIVA DOS MÉTODOS APROXIMADOS DE DIMENSIONAMENTO DE PILARES ESBELTOS DE CONCRETO. In: 60º Congresso Brasileiro do Concreto, 2018, Foz do Iguaçu. 60º Congresso Brasileiro do Concreto, 2018.

Abstract
The present work seeks to analyze the simplified procedures described in ABNT NBR 6118: 2014 for the design of slender columns of reinforced concrete. The standard presents the "Standard abutment method with approximate curvature" and "Standard abutment method with rough stiffness", which is intended for columns with slenderness> 90. The comparative studies of these methods found in the literature have divergent conclusions when it comes to choosing which method best fits the experimental results. Also discussed are proposals for improvements to methods for simplifying the sizing process. Finally, the authors present their conclusions about the methods studied.
Abstract
The present work seeks to analyze the simplified procedures described in ABNT NBR 6118: 2014 for the design of slender columns of reinforced concrete. The standard presents [...]
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Partially saturation effect on fine sands and earth pressure in a sheetpile wall
J. Ruge, F. Molina-Gómez, J. Bastidas, R. Cunha, I. Otálvaro

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (4), 48

Abstract
Generally, the effects of suction in fine sands can be evidenced by a stiffening of the material, as the capillary front advances in the granular skeleton. In geotechnical retention structures this effect can be translated in an increasing of earth pressure, which is not normally considered in geotechnical designs. This study analyzes the capillary effects by implementing a physical modelling in centrifuge and a numerical simulation, using different constitutive models that involve suction within the analysis. The modelling is based on a structure of retention in sheetpiles built on a real scale. Some factors that affect both physical and numerical modelling were taken into account and should be considered in the analysis of the results obtained and, in the comparisons, carried out by both methodologies. As a point of interest, numerical modelling showed less dispersion in the results obtained than physical modelling, these and other aspects are analyzed in the document
Abstract
Generally, the effects of suction in fine sands can be evidenced by a stiffening of the material, as the capillary front advances in the granular skeleton. In geotechnical [...]
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Mono-objective minimization of operation cost for a microgrid with renewable power generation, energy storage and electric vehicles
C. Baron, S. Rivera

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (3), 34

Abstract
The term Microgrid refers to a power system in a small scale, made of active elements operating between them, namely renewable and traditional generation, energy storage and controllable charges. Previous studies have evaluated and modelled the operation cost of many elements that make up the Microgrid, in order to identify the correct point of operation. In this study, the researchers evaluated a model of Microgrid with diesel as traditional generator, a park of photovoltaic generation, two wind generators, one battery bank and two aggregators that manage electric vehicles. The objective of this research is to propose an equation capable of describing the operation cost of a Microgrid as a set, taking into account the modelling of the operation cost of photovoltaic energy, wind energy, and energy storage in battery banks and electric vehicles. This equation also seeks to obtain the best possible cost efficiency, i.e., decreasing the operation cost of the Microgrid. For this purpose, the Metauristic method DEEPSO (Differential Evolutionary Particle Swarm Optimization) was used, recognized for its performance for applications in power systems. Through this method, and determinate the conditions of operation of the different elements in the Microgrid. Taking into account all the parameters, the behavior of each one of the elements of the Microgrid in a 24-hour lapse was found and visualized.
Abstract
The term Microgrid refers to a power system in a small scale, made of active elements operating between them, namely renewable and traditional generation, energy storage and [...]
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Optimization Study For The Cross-Section Of A Concrete Gravity Dam: Genetic Algorithm Model And Application.
L. ARAUJO, A. Vieira, D. Gutstein

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (3), 35

Abstract
Concrete gravity dams have trapezoidal shape in their cross section and shall guarantee the global stability against acting loads like hydrostatic and uplift pressures through his gravitational actions (self-weight and others). This study focuses on the shape optimization of concrete gravity dams using genetic algorithms. In this case, the dam cross section area is considered as the objective function and the design variables are the geometric parameters of the gravity dam. The optimum cross-section of a concrete gravity dam is achieved by the Genetic Algorithm (GA) through a Matlab routine developed by the author. Sliding, overturning and floating verifications are implemented in the program. In order to assess the efficiency of the proposed methodology for gravity dams optimization, one application is presented adopting the concrete gravity dam of Belo Monte Hydropower Plant (HPP), considering normal loading condition and others assumptions presented.
Abstract
Concrete gravity dams have trapezoidal shape in their cross section and shall guarantee the global stability against acting loads like hydrostatic and uplift pressures through [...]
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Mathematical Formulation and Numerical Validation of Uncertainty Costs for Controllable Loads
S. Vargas, D. Rodriguez, S. Rivera

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 16

Abstract
This document presents an analysis in the development of a new mathematical formulation with which it will be possible to determine, through probabilistic approaches, the cost that can be generated if a diversified electricity market existed, in which the demand is able to actively participate. For this, it is considered that the electrical demand in a moment of time has associated a probability distribution and a system that makes it controllable. The cost of uncertainty of demand is mathematically developed by calculating the expected cost of supplying the most convenient demand value for the power system. The validation of the analytical formula is done through the Monte Carlo method, which allows us to compare the penalty costs in the case of underestimating or overestimating the demand for electrical energy.
Abstract
This document presents an analysis in the development of a new mathematical formulation with which it will be possible to determine, through probabilistic approaches, the [...]
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CROSS-SECTION OPTIMIZATION OF CONCRETE GRAVITY DAMS USING GENETIC ALGORITHMS
L. ARAUJO

CROSS-SECTION OPTIMIZATION OF CONCRETE GRAVITY DAMS USING GENETIC ALGORITHMS (2017). XXXVIII Ibero-Latin American Congress on Computational Methods in Engineering

Abstract
Concrete gravity dams are the most commonly used hydraulic structures in engineering, for the designer these structures, the overall stability (external forces) must be guaranteed as well as the internal stresses that element is subjected to. The scaling mechanisms these structures are presented in the manual Critérios de Projeto Civil de Usinas Hidroelétricas (2003) from Eletrobras, which is strongly influenced by the U.S. Bureau of Reclamation (1976). After an analysis of the proposed design forms, it was observed a tendency to oversize these structures, in order to reduce this oversizing and to obtain slender forms of dam, the present work brings an optimization study for the cross sections of concrete gravity dams, this optimization will be made by means of routines used in Matlab software, the genetic algorithm technique will be used to reduce the cross-section of this type of dam and consequently reduce the volume of concrete used in its construction.
Abstract
Concrete gravity dams are the most commonly used hydraulic structures in engineering, for the designer these structures, the overall stability (external forces) must be guaranteed [...]
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Efficient combined SSIM- and landmark-driven image registration in a variational framework
J. Larrey-Ruiz, J. Morales-Sánchez, L. Larrey-Ruiz

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 27

Abstract
Image registration methods are used to establish geometrical correspondences between different datasets. Various characteristics of image data can be exploited to drive image registration algorithms. Thus, the currently available schemes can be roughly divided into two classes: intensity-based and feature-based registration schemes. In this paper, we present a mathematical framework, based on the calculus of variations, for combining these two classes in order to benefit from the advantages of both strategies. The goal is to obtain a registration algorithm which achieves a good matching of datasets near landmark locations but also away from them (by matching the corresponding intensities). The proposed approach includes the novel formulation of a disparity term which simultaneously takes into account the structural similarity index (a similarity measure which considers spatial dependencies in the images) and the location of outstanding points. Since the iteration which results of the variational formulation is translated into the frequency domain, the implementation of the proposed algorithm offers a good speed-performance trade-off when compared to other state-of-the-art image registration implementations. Experimental results show the advantages, in the medical setting, of the combined SSIM- and landmark-based approach over well-established registration techniques which use either landmark or intensity information alone. In particular, the registration of triple-phase 3D computed tomographies of the liver under injection of a contrast agent has been chosen for such a comparison. The datasets are acquired at different times depending on the arrival time of the contrast agent in arteries, portal and hepatic veins, so they have to be registered in order to show the liver structures acquired at each phase in a common framework. These multi-phase studies provide tumor enhancement on the arterial and portal venous phases that support differential diagnosis of lesions in the liver.
Abstract
Image registration methods are used to establish geometrical correspondences between different datasets. Various characteristics of image data can be exploited to drive image [...]
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Análisis del comportamiento del contrato de distribución de ingresos en una cadena de abastecimiento frutícola
D. Peña Orozco, S. Agudelo, L. Rivera

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (2), 31

Abstract
Supply chains are systems characterized by inter-organizational and inter-functional relationships where the markets dynamics and lack of will towards collaborative relationships, lead to each member attempting to maximize their individual performance, generating inefficient global results. To address this problem, it is necessary to adopt appropriate coordination mechanisms to improve the global performance of the decentralized supply chain [10]. Among the coordination mechanisms are information technologies, information exchange and data, joint decision-making and supply contracts [2]. Among the types of contracts, the shared revenue is highlighted, which in addition to promoting coordination in the chain, is concerned with better distribution of income between its echelons [6] by modifying two values to be defined, the wholesale price and income distribution coefficient. In this paper, a mathematical model that represents the revenue sharing contract that attempt to maximize the performance of the supply chain is developed. Finally, a case study in a fruit supply chain composed by three echelons is formulated and the comparative economic results between the current scenario and the scenario using the revenue sharing contract as a coordination mechanism are shown.
Abstract
Supply chains are systems characterized by inter-organizational and inter-functional relationships where the markets dynamics and lack of will towards collaborative relationships, [...]
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Estimation of the transverse sway motion of a biped robot during the march
R. Portillo Vélez, L. Marín-Urias, J. Vazquez-Santacruz, A. Miguelena, A. Marin-Hernandez

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 25

Abstract
Due to the balancing generated by the natural dynamics and disturbances during the march of a biped robot, it is difficult to predict its position at a certain moment along the same, thus complicating the development of tasks like manipulation, cooperation, obstacles, avoidance, servo-visual feedback, among others. In this document, we describe a methodology to predict the sway motion in the transverse plane of a biped robot, given the trajectory of a fixed point in its mechanical structure. It is considered the study of two mathematical models to approximate the rolling movement of the robot: approximation by means of a sinusoidal function and approximation by Fourier series. In both cases, it is necessary to know the parameters involved in each mathematical model, so three parametric approximation techniques are implemented: least squares indentification and algebraic identification for the case of the sinusoidal approach, and the calculation of coefficients for the case of the Fourier series. To validate the methodology, real-time monitoring of a biped robot is carried out since the trajectory of the point of interest is affected by various factors such as friction, inclination and imperfections of the surface, the state of conservation of the robot, among others. From different experiments, a quantitative comparison between the different approaches is developed to verify the one that best reproduces the dynamis of the robot's sway.
Abstract
Due to the balancing generated by the natural dynamics and disturbances during the march of a biped robot, it is difficult to predict its position at a certain moment along [...]
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Experimental evaluation of correlations used to calculate friction factor for turbulent flow in cylindrical pipes
A. Olivares, R. Guerra, M. Alfaro, E. Notte-cuello, L. Puentes

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 15

Abstract
The hydraulic systems that distribute water to users have an important role in their quality of life. For this reason, the precise determination of the friction factor in pipes is of great importance in the design of water distribution networks because it directly influences the calculation of pressure drop (head losses) in hydraulic systems. The objective of the present work was to evaluate in an experimental manner different correlations that describe, in an explicit form, the friction factor in a pipe under turbulent flow and the implicit Colebrook-White correlation. This was done by comparing the numerical values predicted by the correlations in regard to the experimental value, finding that the Colebrook-White correlation predicts the friction factor with the lowest error percentage among the 27 correlations studied. For the solution of the Colebrook-White equation the Newton-Raphson method was used, given that it presents a recurrent structure that can be taken to algorithms and quickly solved by computer programs. In this work, a tool was developed in the C ++ programming language to solve the Colebrook-White equation.
Abstract
The hydraulic systems that distribute water to users have an important role in their quality of life. For this reason, the precise determination of the friction factor in [...]
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Approximation of the scalar convection-diffusion-reaction equation with stabilized finite element formulations of high order
A. Villota, R. Codina

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 6

Abstract
In this paper we present stabilized finite element formulations to solve the scalar convection-diffusion-reaction equation in the case of small diffusion. On the one hand, we summarize the application of the ASGS and OSS formulations based on the concept of variational multiscale methods. On the other hand, we discuss aspects of the use of high order elements, focusing our numerical experiments on quadratic, cubic and fourth order elements. Likewise, the application of the OSS method requires the introduction of a projection, for which we introduce a modification of the fourth order simplicial element with an associated numerical integration rule.
Abstract
In this paper we present stabilized finite element formulations to solve the scalar convection-diffusion-reaction equation in the case of small diffusion. On the one hand, [...]
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Efficiency Maximization of a Jet Pump for an Hydraulic Artificial Lift System
R. Portillo Vélez, J. Vásquez-Santacruz, L. Marín-Urías, A. Vargas, P. García-Ramírez, J. Morales-de-la-Mora, A. Vite-Morales, E. Gutierrez-Domínguez

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 12

Abstract
This work presents a simpler numerical design method for efficiency maximization of an Hydraulic Jet Pump (HJP) for oil-well extraction process, considering its hydraulic and geometric parameters. The design process consists in setting and solving a constrained non-linear optimization problem by taking into account the hydraulic model of the HJP in terms four design variables: throat area, nozzle area, injection flow, and injection pressure to the oil-well. The objective function of this case aims to maximize the HJP's efficiency avoiding to approach cavitation condition as well fulfilling technical constraints. A numerical technique, Differential Evolution Algorithm (DEA), has been implemented to solve the optimization problem. The proposed methodology leads to a solution set by considering only commercial geometries and feasible operating conditions for the HJP, which facilitates its practical implementation. A set of ten oil-wells with land production data, operating in the southeaster of Mexico, is used to compare and validate several Jet pump designs, i. e., through comparison with actual oil-well's operation condition.
Abstract
This work presents a simpler numerical design method for efficiency maximization of an Hydraulic Jet Pump (HJP) for oil-well extraction process, considering its hydraulic [...]
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A geometric description of Discrete Exterior Calculus for general triangulations
R. Herrera, S. Botello, H. Esqueda, M. Moreles

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 2

Abstract
We revisit the theory of Discrete Exterior Calculus (DEC) in 2D for general triangulations, relying only on Vector Calculus and Matrix Algebra. We present DEC numerical solutions of the Poisson equation and compare them against those found using the Finite Element Method with linear elements (FEML).
Abstract
We revisit the theory of Discrete Exterior Calculus (DEC) in 2D for general triangulations, relying only on Vector Calculus and Matrix Algebra. We present DEC numerical solutions [...]
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A methodology for the design of dam spillways with wedge shaped blocks based on numerical modeling
J. San Mauro, M. Toledo, F. Salazar, F. Caballero

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 3

Abstract
Wedge shaped blocks spillways are an innovative solution that allows spilling over the downstream shoulder of earth and rock-fill dams in a safe way. However, they have been barely used as main spillway due to the lack of practical design criteria. An innovative procedure for computer-aided design of wedge shaped blocks spillways is presented in this paper. It includes the design of the drainage and supporting layer considering its seepage capacity and stability. The leakage flow through the joints between blocks is estimated by means of a numerical model calibrated and validated from experimental results. Stability against sliding of the downstream shoulder or the drainage layer is ensured, considering the properties of the granular material selected by the designer and non-linear resistance laws. The procedure will also suggest the shape of a toe protection.
Abstract
Wedge shaped blocks spillways are an innovative solution that allows spilling over the downstream shoulder of earth and rock-fill dams in a safe way. However, they have been [...]
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The effect of the mesh refinement on a multiscale domain decomposition method for the non-linear simulation of composite structures
J. Fernandez, K. Saavedra, J. Hinojosa, P. Flores

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 24

Abstract
This article is focused on the study of a micro-macro LaTIn based Domain Decomposition Method (LaTIn-DDM) for the prediction of the nonlinear behavior of slender composite structures subjected to bending, buckling and delamination. Previous studies have shown that an adequate selection of the iterative parameters (search directions and macroscopic space) allow to improve the convergence rate and ensure scalability (i.e. number of iterations is independent of the number of subdomains) of the iterative schema. To obtain precise solutions, only the size reduction of the subdomains' discretization has been addressed (h-refinement), disregarding the option of increasing the polynomial degree of the finite elements (p-refinement) and ignoring their underlying effects on the information's transmission through the interfaces between subdomains. In this work and using linear and quadratic finite elements, h and p refinements on the subdomains and local h-refinement only along the edges of the subdomains were investigated. It is conclude that the p-refinement in the whole subdomain not only enables to reach more exact solutions than using global or local h-refinement, but also the convergence rate is improved. These enhancements allow more complex simulations but using less degrees of freedom and less calculation time, even up to 97% faster.
Abstract
This article is focused on the study of a micro-macro LaTIn based Domain Decomposition Method (LaTIn-DDM) for the prediction of the nonlinear behavior of slender composite [...]
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Dynamic Analysis of Hypar Membrane Structures Subjected to Seismic Excitations
J. Valdes-Vazquez, A. García-Soto, A. Hernández-Martínez

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 11

Abstract
The seismic response of tensile membrane structures (TMS) is investigated. To the authors knowledge, this is the first study on TMSs subjected to a seismic record reported in the literature. A type of membrane structures usually considered as a reference in other works are employed in the present study. The selected hyperbolic-paraboloid fabric structures, also referred as hypar TMSs, are subjected to an earthquake accelerogram from a relatively large earthquake recorded at Norcia, Italy. To obtain the TMSs seismic re- sponse, a finite element formulation reported in a previous study, and which accounts for wrinkling phenomena, orthotropic material modeling, and geometrical nonlinearity, is employed. The analyses are performed in two stages; first for the prestressed case and then the seismic loading is added. It is found that the seismic response of TMSs should not be disregarded by designers beforehand, since important increments in the dynamic response of the displacements produce an incremet of around 9% for stresses. However, a very important increment of around 80% for support reaction forces is computed, when compared with the static case. It is also found that the orientation of the frame-supporting structure has a significant impact on the computed seismic reactions.
Abstract
The seismic response of tensile membrane structures (TMS) is investigated. To the authors knowledge, this is the first study on TMSs subjected to a seismic record reported [...]
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On the robustness of the multigrid method combining ILU and Partial Weight applied in an orthotropic diffusion problem
G. Vassoler Rutz, M. Augusto Villela Pinto, S. de Fátima Tomazzoni Gonçalves

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 23

Abstract
This paper proposes an efficient and robust algorithm for solving a physical orthotropy problem. The algorithm is based on choosing the most efficient restriction operator and on an incomplete LU decomposition suited for each orthotropy direction. Local Fourier Analysis (LFA) is carried out in order to increase the efficiency of the multigrid method. Pure diffusion with orthotropy aligned to the coordinate axis x is the model considered. Equations are discretized by Finite Difference Method with uniform grid and second-order numerical scheme. Problems are solved with geometric multigrid method, correction scheme, V-cycle and standard coarsening ratio. The asymptotic convergence factor is calculated for different multigrid components, such as restriction operators, prolongation operators and solvers. Based on the optimum components obtained by LFA, we carried out experiments to analyze the complexity and computational cost of the algorithm proposed. The main conclusion is that the methodology proposed is efficient for the resolution of problems with strong orthotropy.
Abstract
This paper proposes an efficient and robust algorithm for solving a physical orthotropy problem. The algorithm is based on choosing the most efficient restriction operator [...]
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Modified simulated annealing algorithm for optimal design of steel structures
C. Millan, J. Filho

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 26

Abstract
Structural optimization aims to design structures under certain constraints to achieve better behavior and have a proper manufacturing cost. This type of optimization corresponds to highly non-linear and non-convex problems including several local optima. Therefore, to solve such problems effectively, designers need to use adequate optimization methods which can make a good balance between the computational cost and the quality of solutions. In this paper the modified simulated annealing algorithm (MSAA) is employed to solve optimal design of steel structures. MSSA is a newly improved version of the simulated annealing (SA) algorithm with three modiﬁcations: preliminary exploration, search step and a new probability of acceptance. The performance, robustness and applicability of the MSAA are demonstrated through six structural optimization problems. Obtained results in all considered examples indicate that the MSAA is superior to several other methods in existing literature in terms of the quality of solution and convergence speed.
Abstract
Structural optimization aims to design structures under certain constraints to achieve better behavior and have a proper manufacturing cost. This type of optimization corresponds [...]
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Optimum design of composite twin-girder road bridges
J. Baraibar, E. Baraibar

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (3), 41

Abstract
Composite structures have not been able to compete in Spain with more conventional prestressed concrete bridges in the lower range of medium spans (30 - 90 m.). In this context, twin-girder sections are revealed as a more competent typology because of its sobriety, ease of construction and good structural performance. At present the optimal character of the designs in structural projects is rarely challenged. The present study undertakes an in-depth analysis of the twin-girder section, involving a complete optimisation for the deck. To this end a specific 2D grillage model has been developed, integrating the composite and evolutive character of twin-girder decks, as well as the instability phenomena inherent to thin-walled structures. Several conclusions are drawn after a parametric calculation using this model, regarding the optimum dimensions of all the variables that define the twin-girder section. These conclusions crystallise in a series of formulas that can be used as a design guide.
Abstract
Composite structures have not been able to compete in Spain with more conventional prestressed concrete bridges in the lower range of medium spans (30 - 90 m.). In this context, [...]
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Dynamic analysis in the domain of frequency by the method of the harmonic balance
R. Zaltron, F. Neves

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 10

Abstract
The analysis of structures in the frequency domain has been gaining ground in the last decades, first, because of the computational development and strategies to evaluate the Discrete Fourier Transform more efficiently. The advantages of evaluating the frequency response are that there is no need to know the initial conditions, and the response to systems with frequency-dependent properties can be evaluated more accurately, eg, soil-structure interaction. This work aims to evaluate the dynamic response of a discrete structural system in the frequency domain through the resonance curves using the Harmonic Balance Method HBM. The response is evaluated in the permanent phase for actions and / or harmonic loads for systems with proportional and non-proportional viscous damping. The properties of the system, such as mass and rigidity, are taken as constants. For the models developed and analyzed in this study are presented the respective spectra of frequency response and history of displacement in time through the HBM. The system responses obtained through the HBM are compared with two other methods also based on the frequency domain (ImFT and PseudoForces), allowing to evaluate the amplitudes and critical frequencies of the system.
Abstract
The analysis of structures in the frequency domain has been gaining ground in the last decades, first, because of the computational development and strategies to evaluate [...]
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A rapid aeroelasticity optimization method based on the stiffness characteristics
Z. Yuan, S. Huo, J. Ren

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 4

Abstract
A rapid aeroelasticity optimization method based on the stiffness characteristics was proposed in the present study. Large time expense in static aeroelasticity analysis based on traditional time domain aeroelasticity method is solved. Elastic axis location and torsional stiffness are discussed firstly. Both torsional stiffness and the distance between stiffness center and aerodynamic center have a direct impact on divergent velocity. The divergent velocity can be adjusted by changing the correlative structural parameters. The relation between structural parameters and divergent velocity is introduced to aeroelasticity optimization design as a constraint condition. After optimization, the structural and aerodynamic characteristics have a large improvement while satisfying the constraint conditions. The optimization method can be well used in high aspect ratio wing and has great computational efficiency.
Abstract
A rapid aeroelasticity optimization method based on the stiffness characteristics was proposed in the present study. Large time expense in static aeroelasticity analysis based [...]
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Interval-based Recording of Generated Pseudorandom Numbers
V. Tomašević, M. Tomašević, S. Bojanic

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (2), 33

Abstract
For some applications that use pseudorandom numbers it is essential to keep the record of numbers generated so far. Such a representative example is cryptanalytic TMTO approach. In order to save the space, instead of straightforward recording of individual numbers generated, an ordered tree-like data structure which tracks the intervals of generated numbers is proposed. For estimating the memory requirements of this structure as a function of pseudorandom numbers range size, an analytical probabilistic model is established and used. This model determines the maximum number of intervals during recording which corresponds to the tree size. The result obtained from analytical model is fully validated experimentally by means of simulation for a wide spectrum of range sizes.
Abstract
For some applications that use pseudorandom numbers it is essential to keep the record of numbers generated so far. Such a representative example is cryptanalytic TMTO approach. [...]
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Structural health monitoring by combining machine learning and dimensionality reduction techniques
G. Quaranta, E. Lopez, E. Abisset-Chavanne, J. Duval, A. Huerta, F. Chinesta

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 20

Abstract
Structural Health Monitoring is of major interest in many areas of structural mechanics. This paper presents a new approach based on the combination of dimensionality reduction and data-mining techniques able to differentiate damaged and undamaged regions in a given structure. Indeed, existence, severity (size) and location of damage can be efficiently estimated from collected data at some locations from which the fields of interest are completed before the analysis based on machine learning and dimensionality reduction techniques proceed.
Abstract
Structural Health Monitoring is of major interest in many areas of structural mechanics. This paper presents a new approach based on the combination of dimensionality reduction [...]
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Design and manufacture of a customised temporomandibular prosthesis
C. Miguel, J. Hernández-Gómez, G. Urriolagoitia-Sosa, B. Romero-Ángeles, L. Martínez-Sáez

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 22

Abstract
In this work, design, manufacture and surgical success of a personalised temporomandibular prosthesis is featured. A fused deposition modelling technique and Die forging process constitute the methodology used in a patient who had an amputation in the upper third branch of the mandible, without considering the joint capsule. The implant was designed using a processed resection image of a computational tomography and using the methodology of Özkaya and Nordin. The jaw operating conditions were simulated by the finite element method (FEM). The main considered factors were the morphological geometry of the patient, implant fixation in the first third of the branch, implant fixation on the chin, dental post for placement of the teeth, and the form of the sub-lingual fossa weight optimisation. Special consideration was to preserve the patients facial aesthetics.
Abstract
In this work, design, manufacture and surgical success of a personalised temporomandibular prosthesis is featured. A fused deposition modelling technique and Die forging process [...]
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Damping performance of viscoelastic material applied to blades
F. Wang, Z. Wei, B. Xu

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 9

Abstract
'''High-frequency vibration can result in failure of the working blades. So suppressing vibration failure of blades becomes more and more important. Damping performance of viscoelastic block on blades is researched based on principle of finite element method, contact theory of elastic body and the solving equations of natural frequency. Modal and harmonic response is analyzed to obtain natural frequency, vibration displacement and stress, in which different finite element models of blade are established. Effects of different adding position and thickness of viscoelastic block on damping performance are analyzed. Elastic modulus and loss factor of viscoelastic material is also changed to study their influence on damping performance. The results show that viscoelastic block applied to blades has excellent performance in reducing blade vibration. When viscoelastic block is added to mortise side, the damping performance of blade is the best. In addition, thickness of viscoelastic block and parameters of viscoelastic material have a significant effect on vibration reduction of blade. '''Key words''': Viscoelastic damping material, blades, vibration reduction, modal analysis, harmonic response Corresponding author. E-mail: [mailto:fswang@nwpu.edu.cn fswang@nwpu.edu.cn] (Fusheng Wang)
Abstract
'''High-frequency vibration can result in failure of the working blades. So suppressing vibration failure of blades becomes more and more important. Damping performance [...]
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Assessment of methods of identification of dynamic properties based on measured seismic response of a building
P. Alcaíno, H. Santa-María

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 7

Abstract
The structural monitoring, which is becoming increasingly common, makes it necessary to choose one or more methods of processing and analyzing the obtained data. This choice is key to meeting the objectives of this monitoring. Considering that there are many methods with different capacities and requirements, this choice is a complex problem. This paper presents a methodology for the assessment and selection of methods for the identification of dynamic response properties of buildings using vibration monitoring. In this work, well-known methods based on time domain analysis (subspace-state) and non-parametric methods based on the frequency domain are studied when applied to seismic vibration records for a reinforced concrete building instrumented with a network of tri-axial force-balance accelerometers. For two and a half years, the sensor network has recorded close to 500 sensitive earthquakes. Nonetheless, it only includes those with a magnitude higher than 4.8 (ML or MW) and that occurred between September, 2015 and September, 2016. Using six versions of identification methods, modal response parameters are determined for each of the two main directions of the building, considering different levels of information acquired by the sensor network (floor information). An assessment of the performance of each method is conducted based on the number of identified modal frequencies and damping ratios; their variability (coefficient of variation); and the processing time of each method. As a result and conclusion regarding the use of this methodology, it is not only possible to choose the most convenient method for processing vibration records applied to structural health monitoring (SHM) according to its own objective, but also to progressively improve the design of the sensor network.
Abstract
The structural monitoring, which is becoming increasingly common, makes it necessary to choose one or more methods of processing and analyzing the obtained data. This choice [...]
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Elasto-plastic finite element analysis of reinforced concrete T-shaped column frame joint
Y. Liu, X. Ren, H. Liu

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 13

Abstract
By the integral finite element analysis of elasto-plastic constitutive relationship, the process of crack formation and development of the T-shaped frame joint in reinforced concrete and its stress distribution under monotonic and low-cycle repeated loading were studied . The nonlinear constitutive relation of concrete and the failure mechanism of T-shaped column joint were further discussed. The work of this paper provides a reference to the design and construction of T-shaped column joints.
Abstract
By the integral finite element analysis of elasto-plastic constitutive relationship, the process of crack formation and development of the T-shaped frame joint in reinforced [...]
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Structural assessment of gravity dams by means of a semi-discrete approach
F. Peña

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 19

Abstract
A new numerical model for the structural assessment of gravity dams by means of a semi-discrete approach is proposed. Gravity dams are massive structures, which their stability depends on the gravity loads applied into the structure. Mainly, its structural assessment is performed by means of a gravity approach. However, this approach is too conservative and mostly does not reflect the real structural behaviour of the dam. In this context, there is the need of models that are simplified enough to allow a simple and fast parametric analyses. The proposed model idealizes the dam as a set of rigid elements, where the damage and the deformation are concentrated in the contact sides between adjacent elements. Thus, the elements are rigid, but the material is considered as deformable. As the proposed model is semi-discrete, it can detect separation or sliding between elements. However, initial contacts do not change during the analyisis and a relative continuity among elements exists, in order to simplify the computational effort. The effective performance of the proposed model is demonstrated by numerical validation and by comparisons with some numerical models presented in the literature.
Abstract
A new numerical model for the structural assessment of gravity dams by means of a semi-discrete approach is proposed. Gravity dams are massive structures, which their stability [...]
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Positioning system for 3D scans inside objects
S. Cano-Rodríguez, J. Gonzalez-Barbosa, F. Ornelas-Rodríguez, J. Hurtado-Ramos, O. Icasio-Hernández

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 17

Abstract
In this work we present an active positioning system for 3D scan of interior parts. The design of the proposed system consists of two modules: an active 2D dimensional system and positional system based on active vision. The active 2D dimensional system is able to determine the depth of the 2D dimensional system inside the object to be scanned using several sensors. The main contributions of this work are the characterization of the 2D dimensional system and the development of active light positioning algorithms with emphasis on the modeling and fusion of the sensors. The system can be used as a dimensional system in industrial applications such as the metal mechanical industry, aeronautics industry, medicine, quality control and computer vision.
Abstract
In this work we present an active positioning system for 3D scan of interior parts. The design of the proposed system consists of two modules: an active 2D dimensional system [...]
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Annual distribution of the Sun’s angular positions, study at 21 degrees of latitude
C. Acosta, O. Carvente-Muñoz, F. Peñuñuri-Anguiano, M. Zambrano-Arjona, G. Rivadeneyra-Gutiérrez

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 5

Abstract
It is well know that the Sun position, measured over the heart surface is a function of the latitude and the hour of a particular day. Usually, the Sun follows a different path from one day to the next, and this is determined by the azimuth and zenith angles. The analytical calculations for determining the angular position at any time (solar hour) are an overwhelming task. We use the Mathematica® software to write a home code for determining at any time (in intervals of one minute) and latitude, the azimuth and zenith angles of the Sun for every day of the year. In order to show general results of interest, in this work we present the annual distribution of the angular positions and the length of the day (hours of light) for the 21 degrees of latitude. This information could be used for optimizing the orientation of solar panels and collectors and for the design of cheap houses where the walls can be exposed to the minimal solar incidence.
Abstract
It is well know that the Sun position, measured over the heart surface is a function of the latitude and the hour of a particular day. Usually, the Sun follows a different [...]
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Thermal model of a solar concentration cooker: a parameter variation study to estimate thermal properties
M. Gonzalez-Aviles, J. AVILES, H. CAMPUZANO

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 21

Abstract
This document describes the development of a thermal model to explain the behavior of a solar concentration cooker. The model is presented in terms of a coupled system consisting of three ordinary, differential non-lineal equations used to calculate average temperatures of the surface of the reflectors, the surface of the container, and the liquid placed inside the container. Numerical results compared to measurements from experimental tests show that good concordance was obtained. A study of variation was conducted using some of the design parameters of the solar cooker to estimate standard cooking power and thermal efficiency. We conclude that the parameter ‘emittance of selective absorbent film’ on the surface of the cooking pot exerts the greatest influence on the thermal properties assessed.
Abstract
This document describes the development of a thermal model to explain the behavior of a solar concentration cooker. The model is presented in terms of a coupled system consisting [...]
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3D printed scaled setup for smoke transport analysis in a subterranean passenger platform
L. Flores-Herrera, R. Rivera-Blas, J. Pérez-Cruz, N. Muñoz-Aguirre, C. Torres-Martínez, M. Carbajal-Romero, R. Vargas-Carmona, M. Funes-Lora

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 1

Abstract
In this work, the study of smoke fire transportation inside of a subway passenger platform is presented. The study includes a set of numerical simulations to observe the behavior of the air inside the platform. Two smoke transport simulations using the FDS program are also included. Subsequently, the development of a 3D - 1:100 scale model is described and it was used to perform an experimental observation of the phenomenon. The model was built by using a 3D printer which allowed to include more architectural details of the real scenario. The inclusion of these details allowed to observe qualitative similarity between the results of the simulation and the experimental work. Although there are clear differences between what could happen in a real scenario and what was observed in the scale model, it was identified that the model is an important complement to the simulations. In addition to the simulations, the use of this type of 3D models allows the observation of the phenomenon by different specialists such as firefighters, policeman, medical personnel, etc., in the same place and its intention is to provide a more interactive tool to the observation group, increasing the time devoted to the development of contingency actions and reducing the costs associated with the logistics of a real simulacrum. The model allows to better identify the strengths, opportunities, weaknesses and threats of the contingency procedures developed by the safety and hygiene groups and to make their corresponding adjustments if necessary.
Abstract
In this work, the study of smoke fire transportation inside of a subway passenger platform is presented. The study includes a set of numerical simulations to observe the behavior [...]
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Analysis and design of concrete structures using strut and tie model by FEM: Application in foundation blocks, short consoles, wall beams and rigid shoes
M. LIMA, P. ROCHA, R. SILVEIRA, K. SILVA

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (2), 30

Abstract
The present work has as main objective to perform elastic-linear analyzes through a computational program with numerical approach of the strut-and-tie model using a formulation based on the Finite Element Method (FEM). In this model, it is possible to analyze the behavior of structural elements such as foundation blocks, wall beams, short consoles, also represent the values of tensions, deformations and displacements in the region of a beam represented as the Model of cranks developed by MONTOYA et al. [1], besides numerically modeling via FEM a wall beam with a large aperture, developed by SCHLAICH et al. [2]. In order to validate the numerical implementations, the results were compared with numerical modeling performed with the aid of ANSYS software 17 and with normative expressions.
Abstract
The present work has as main objective to perform elastic-linear analyzes through a computational program with numerical approach of the strut-and-tie model using a formulation [...]
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Change of effective properties of concrete by alkali-silica reaction
G. Augusto Pianezzer, L. Gramani, E. Kaviski

Rev. int. métodos numér. cálc. diseño ing. (2019). Vol. 35, (1), 8

Abstract
The present work develops a model of computer simulation of the actual properties of concrete under the action of alkali-silica reaction. Obtains a computational representation from the analysis of the chemical reaction and homogenenization techniques. Alkali-Silica reaction forms a gel that changes the effective properties of concrete and can lead to damage to structures, especially of hydroelectric dams. The model consists of three phases, generation of representative element of concrete, gel formation and dissemination by alkali-silica reaction and homogeneization of the final material. The first stage is the development of representative concrete element that is simulated from the granulometric curve and uses a computacional collision detection algorithm to ellipses. To model the behavior of chemical evolution, it uses a system based on equations of chemical kinetics, known as Guldberg - Waage Law and uses a gel diffusion model developed to mesh of representative element of concrete. To model the variation of the effective properties, it uses homogenization schemes (Reuss method, Voigt Method, Self-Consistent method and Mori-Tanaka method) to provide, thus, elasticity coefficientes of the composite material. The combination of the models allowed to predict the evolution and damage to the material over time and analyze the influence of the volume fraction of agregates in the lifetime of concrete.
Abstract
The present work develops a model of computer simulation of the actual properties of concrete under the action of alkali-silica reaction. Obtains a computational representation [...]
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