The second public workshop of the FIBRESHIP project offered to the participants a chance to discuss the different composite materials solutions for shipbuilding as well as learn more about the latest technological advances of FIBRESHIP Project related to design, construction and operation of ships integrally built in composite materials. FIBRESHIP Consortium is looking for a niche in the future shipping market through promoting changes in the regulatory framework of IMO and generating guidelines and methodologies for designing, building and operating large-length vessels, laying the foundations of a new market based on composites technology in shipbuilding and shipping.

This presentation shows interesting results about the mechanical behaviour of sandwich structures under cyclic fatigue stresses. To address this study, a wide variety of experimental tests as per example digital image correlation or tomography analysis were carried out to investigate the failure modes of these materials. Moreover, the fire behaviour of these sandwich structures is investigated using advanced simulation tools based on finite element analysis.

The second public workshop of the FIBRESHIP project offered to the participants a chance to discuss the different composite materials solutions for shipbuilding as well as learn more about the latest technological advances of FIBRESHIP Project related to design, construction and operation of ships integrally built in composite materials. FIBRESHIP Consortium is looking for a niche in the future shipping market through promoting changes in the regulatory framework of IMO and generating guidelines and methodologies for designing, building and operating large-length vessels, laying the foundations of a new market based on composites technology in shipbuilding and shipping.

In this presentation, Txuma Iturgáiz on behalf of MTorres introduced the field of activity of his company which is focused on the development of new innovative machines with a high level of automatization for manufacturing and testing composite laminates. Txuma suggested that the most advanced technologies for composite manufacturing can be applied for the shipyards in the construction of a new generation of lightweight ships with the advantages of reasonable cost, flexibility and outstanding quality, extrapolating the advances reached in aeronautical and automotive sectors.

The second public workshop of the FIBRESHIP project offered to the participants a chance to discuss the different composite materials solutions for shipbuilding as well as learn more about the latest technological advances of FIBRESHIP Project related to design, construction and operation of ships integrally built in composite materials. FIBRESHIP Consortium is looking for a niche in the future shipping market through promoting changes in the regulatory framework of IMO and generating guidelines and methodologies for designing, building and operating large-length vessels, laying the foundations of a new market based on composites technology in shipbuilding and shipping.

This presentation explains the development of a new software suite with a wide variety of ad-hoctools to simulate the structural and fire performance of the lightweight composite ships developed within the FIBRESHIP project. The computational analysis tool is based on a fast-numerical software which can be used for the simulation of fatigue, fire diagnosis, thermal propagation, hydro-structural analysis and so on. A Betha version of the developed software suite of this numerical tool is available for the partners of the project.

In this thesis starting from a 7-dimensional metric for the three cases: plane, elliptical and hyperbolic, we obtained the ecs. of Einstein 7-D. Then, solutions to these equations were corroborated in a vacuum. And finally I found a solution for ecs. 6-D with density of matter.

En esta tesis partiendo de una métrica 7-dimensional para los tres casos: plano, elíptico e hiperbólico, se obtuvieron las ecs. de Einstein 7-D. Luego se corroboraron soluciones a dichas ecuaciones en el vacío. Y por último encontré una solución para las ecs. 6-D con densidad de materia.

New numerical developments include: integration schemes for large-strain, elasto-plastic constitutive models, novel integration methods for rigid body contact constraints and stabilized mixed formulations for single-phase and two-phase problems.

An explicit stress integration scheme is developed for elasto-plastic, large-strain constitutive models using a multiplicative split of the deformation gradient. This scheme uses adaptive substepping and a yield violation drift correction technique.

Rigid bodies with pre-specified shape and motion may be modeled. Contact constraints are introduced using a penalty method in which tangential behavior is treated with an elasto-plastic analogy. This elasto-plastic contact model is integrated by means of an implicit integration technique; an alternative scheme using the Implex algorithm is also described and assessed.

Low-order (linear) elements are employed to speed computation. These elements may suffer volumetric locking in quasi-incompressible conditions. For soils, such conditions appear under undrained loading or at critical state. To alleviate this problem, mixed formulations are developed and stabilization techniques are applied. Two different three-field mixed formulations for the coupled hydro-mechanical problem are presented, adding either the effective pressure or the Jacobian as nodal variables to the solid skeleton displacement and water pressure. Stabilization terms are used in the mass conservation equation of the biphasic medium and in the rest of scalar equations. Several mixed formulations are also implemented for the simplified single-phase problem, which approximates saturated soil behavior under undrained conditions.

The first application examples are three total stress problems: indentation of a rigid strip footing, T-Bar motion and a rough cone penetration test. All are frequently used benchmark problems; they allow to compare the performance of the developed numerical scheme with other techniques. It appears that the numerical strategy followed by PFEM, obtains similar results than those attained with alternative numerical methods with significant savings in computational efforts.

A total stress approach is also used in a parametric study of tube sampling in clay. The parameters explored include sampler geometry (round-tipped or beveled cutting shoes; outer diameter to wall thickness ratios); constitutive parameters, roughness factor and boundary conditions are studied. Outputs are analyzed in terms of classical sampling disturbance measures: the centerline strain path and the specific recovery ratio. The results show good agreement with experimental evidence and question the frequently accepted reference role of Strain Path method solutions.

The set of simulations in which a rough interface behavior is considered has been used to assess the theory proposed by Paikowsky and Whitman (1990) to predict the occurrence of a plug inside of an open-ended pile. The numerical results obtained here corroborate this theory: a plug inside of the tube is formed once the mobilized forces are equal to those that would mobilize a smooth closed-ended pile. Indeed, the failure mechanism that prevails during the penetration of a plugged tube is coincident with that of a closed-ended pile.

The last analysis of this work is the hydro-mechanical simulation of the cone penetration test in a Modified Cam Clay soil. A parametric analysis covers the effect of the permeability of the soil -from drained to undrained conditions- and the interface friction angle. The effect of these parameters on the cone resistance, sleeve friction and pore pressure at three potential measurement points is fully characterized. These numerical results are used to assess several techniques to estimate the permeability of soils from CPTu testing. Special attention is paid to on-the-fly techniques, in which permeability could be directly estimated from the CPTu data stream without the need for any stoppage.

The aim of this work to optimization of the heating system by electrical resistances for a rapid thermal response mold (MRTR), using the response surface methodology (MSR). Applying the design technique of the Box-Behnken experiments, a matrix of experiments with four factors and three levels was designed. The design variables that are used to describe the design and shape of the heating system are the heat flux per unit area of the electrical resistance, the distances from the center of the heaters to the surface of the cavity, the distance between the adjacent electrical resistors and the thickness of the heating plate. The heating time, the variation of the temperature in the cavity and the Von-Mises stress were considered as the variables of the model. Thermal and thermal-structural resistance analyzes of the model based on finite element method (FEM) are performed to acquire the objective variables. Mathematical response surface models are developed using the mixed regression model and the response surface model and the variance analysis method (ANOVA) is used to verify the accuracy of these mathematical models. With the obtained models, the position of the electric resistances is optimized and the ratio between mass and volume of the cavity insert is reduced to minimize the heating time within a reasonable temperature distribution and structural strength, coupling the surface models of response developed with the method of particle swarm optimization (PSO). The results obtained indicate that the required heating time on the surface of the cavity can be significantly reduced in the molding cycle, demonstrating with these the effectiveness of the heating system.

The relationship between sleep and caffeine has been widely investigated, it has been established that this methylxanthine can prolong sleep latency, generate less total sleep time with decreased deep sleep and a parallel increase in light sleep (2).

Then, a review is presented that addresses the effect of caffeine on the polysomnographic stages of sleep and on the biological interactions that this substance presents in the adenosine receptors to which it joins; In addition, the genetic variations of these receptors will be taken into account, as possible causes of the changes induced by caffeine in sleep.

In this project, the feasibility of using augmented reality (AR) to assist open liver surgeries was studied. Separate volumes of liver surface, vascular and tumor structures were delineated from an animal's liver CT scan. These were then 3D printed and further rendered by means of a custom application within the HoloLens™ head-mounted display. The accuracy of image registration was subjectively evaluated by checking the alignment of the visible structures between the virtual model and the 3D printed model. By using a combination of tracked hand gestures and voice commands, the AR setup developed successfully indicated with high accuracy the location of the tumor and vasculature of the liver model. These significant results suggest that the superimposition of structures onto the patient liver could facilitate the orientation and navigation during a surgery. This would result in the improvement of tumor resection, leading to an increasing patient safety.

We propose a numerical approach, the Discrete Volume Method, to simulate fracture of brittle materials without the disadvantages mentioned, by combining the benefits of variational formulations and the numerical convenience of discrete element method to capture the dynamics of cracks. The Discrete Volume Method does not have microparameters, since the displacements are computed using the material properties and the fracture mechanism is controlled by an auxiliary damage field.

Within this work we discuss a numerical strategy to solve the elasticity problem upon unstructured and non conforming meshes, allowing all kinds of flat-faced elements (polygons in 2D and polyhedra in 3D). The core of the formulation relies on two numerical procedures the Control Volume Function Approximation (CVFA), and the polynomial interpolation in the neighborhood of the control volumes, which is used to solve the surface integrals resulting from applying the divergence theorem. By comparing the estimated stress against the analytical stress field of the well known test of an infinite plate with a hole, we show that this conservative approach is robust and accurate. A similar strategy is used to get the damage field solution.

In order to coupling both fields, displacement and damage, we use a finite increment arrangement for reducing the resdidual of elastic equation within each time step.

We develop a numerical formulation for time discretization based on the analytical solution of the differential equation resulting from assuming a continuous variation of internal forces of the system between time steps.

Finally, we show the effectiveness of the methodology by performing numerical experiments and comparing the solutions with published results. 

REFERENCES

[1] F. Rastellni, S. Oller, O. Salomon, E. Oñate Composite materials non-linear modelling for long fibre reinforced laminates: continuum basis, computational aspects and validations, Computers & Structures, 86 (9) (2008), pp. 879–896
[2] European Union’s Horizon 2020 research and innovation programme under grant agreement nº 723360 “Engineering, production and life-cycle management for the complete construction of large-length FIBRE-based SHIPs”. http://www.fibreship.eu/about

RETOS Y DESAFIOS Perspectivas de la Educación y La Empresa

Colección de Investigación en  Educación, Empresa y Sociedad -  ISBN: 978-958-52030-1-3 Editorial EIDEC

First, the basic features of each tools are explained. Second, a coupling strategy to assess the performance of FWTs is presented. Third, the results obtained coupling SeaFEM-FAST are used for an inter-code comparison against those obtained coupling Hydrodyn-FAST. Forth, an intensive analysis of a FWT based on the NREL 5 MW baseline is carried out taking into account the environmental conditions of the selected location. These coupled computations are carried out following the Design Load Cases proposed by IEC rules [7] to assess the Ultimate Limit State (ULS). Finally, some comparison and conclusions based on the obtained results are drawn.

The computational tool developed in this work is based on the coupling of a Semi-Lagrangian Particle Finite Element Method (SL-PFEM) with a multi rigid-body dynamics tool. The Particle Finite Element Method [1] is a versatile framework for the analysis of fluid-structure interaction problems. The PFEM combines Lagrangian particle-based techniques with the advantage of the integral formulation of the Finite Element Method (FEM).

It has been shown [1][2] to successfully simulate a wide variety of complex engineering problems, e.g. free-surface/multi-fluid flows with violent interface motions, multi-fluid mixing and buoyancy-driven segregation problems etc.

The latest development within the framework of the PFEM is the X-IVAS (eXplicit Integration along the Velocity and Acceleration Streamlines) scheme [2][3]. It is a semi-implicit scheme built over a Semi-Lagrangian (SL) formulation of the PFEM.

In this work, the SL-PFEM model has been coupled with a multibody dynamics solver, able to handle the interactions between thousands of bodies, representing the different ice blocks. The interaction between the fluid flow and the ice blocks is taking into account by enriching the finite element space at the boundaries of the different blocks.

This work is part of the research project NICESHIP sponsored by the U.S. Office of Naval Research under Grant N62909-16-1-2236.

A finite element-based model is used for the computational simulation. To follow the evolution of the oxide layer originally placed between the butted surfaces, a material tracing technique is incorporated in the numerical model. This approach allows tracking the position of the tracers representing oxide layer particles knowing the nodal velocities.

A robust and fast two-stage numerical strategy is adopted for the analysis of FSW process to solve the underlying thermo-mechanical problem. The first stage is a speed-up stage solved on a fixed mesh that allows to quickly obtain the steady state. Oxide layer evolution is traced in the second stage where the rotation of the tool is modelled.

Experimentally, to produce a clearly dispersed oxide line in the weld, one of the workpieces is anodized while the other one is taken as extruded.

The computationally obtained oxide layer patterns are compared to those obtained experimentally using macrograph analysis of the joint cross section. The effect of the pin features and the process parameters on the final result is studied. The results show that with appropriate modelling of the material tracers in FSW, significant agreement can be attained between the computed and measured post-FSW oxide layer evolved results.