<![CDATA[Scipedia: Documents published in 2021]]> https://www.scipedia.com/sitemaps/year/2021?offset=1000 https://www.scipedia.com/public/Pakvis_et_al_2021a Mon, 12 Jul 2021 08:38:09 +0200 https://www.scipedia.com/public/Pakvis_et_al_2021a <![CDATA[Modeling, Topology Optimization and Experimental Validation of Glass-Transition-based 4D-printed Polymeric Structures]]> In recent developments in the field of multi-material additive manufacturing, differences in material properties are exploited to create printed shape memory structures, which are referred to as 4D-printed structures. New printing techniques allow for deliberate introduction of prestresses in the specimen during manufacturing. This prestress is combined with a heat-induced glass transition, which lowers the materials Young's modulus. Upon the decrease in stiffness, the prestress is released, which results in the realization of a pre-programmed deformation. Coupled with the right design, this enables new functionalities. As the design of such functional multi-material structures is crucial but far from trivial, a systematic methodology is developed, where a finite element model is combined with a density-based topology optimization method to describe the material layout. The coupling between the definition of the prestress and the material interpolation function used in the topology description is addressed. The efficacy of topology optimization to design 4D-printed structures is explored by applying the methodology to a variety of design problems. Tests are performed with printed samples to calibrate the prestress and to validate the modeling approach. This study demonstrates that by combining topology optimization and 4D-printing concepts, stimuli-responsive structures with specific properties can be designed and realized.

]]> Scipedia content https://www.scipedia.com/public/Barbi_et_al_2021a Mon, 12 Jul 2021 08:37:59 +0200 https://www.scipedia.com/public/Barbi_et_al_2021a <![CDATA[Simulation of TALL-3D experimental facility with a multiscale and multiphysics computational platform]]> This work details the development of a computational platform in joint collaboration between the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (enea) and the University of Bologna (unibo). The platform is based on the open-source SALOME software that integrates the CATHARE system code for nuclear safety, FEMUS and OpenFOAM CFD codes in a unique framework, with efficient methods for data exchange. The computational platform has been used to simulate complex multiscale and multiphysics systems, such as the tall-3d facility, with a defective boundary condition approach on overlapping domains. The tall-3d experimental facility has been realized with the purpose of providing reference results to be used for both standalone and coupled System Thermal-Hydraulic (STH) and Computational Fluid Dynamic (CFD) code validation. The transient phenomenon of unprotected loss of lead-bismuth eutectic (LBE) flow that has been experimentally simulated at tall-3d is here studied. The system code is used to simulate the tall-3d apparatus while the CFD code is used to get a better insight into the fluid streaming occurring in the main tank component and improve the system code predictions. A flow transition from forced to natural convection is used to validate the codes and the platform ability to reproduce the experimental data.

]]> Scipedia content https://www.scipedia.com/public/Chierici_et_al_2021c Mon, 12 Jul 2021 08:37:48 +0200 https://www.scipedia.com/public/Chierici_et_al_2021c <![CDATA[FEMuS-Platform: a numerical platform for multiscale and multiphysics code coupling]]> Nowadays, many open-source numerical codes are available to solve physical problems in structural mechanics, fluid flow, heat transfer, and neutron diffusion. However, even if these codes are often highly specialized in the numerical simulation of a particular type of physics, none of them allows simulating complex systems involving all the physical problems mentioned above. In this work we present a numerical framework, based on the SALOME platform, developed to perform multiscale and multiphysics simulations involving all the mentioned physical problems. In particular, the developed numerical platform includes the multigrid finite element in-house code FEMuS for heat transfer, fluid flow, turbulence and fluid-structure modeling; the open-source finite volume CFD software OpenFOAM; the multiscale neutronic code DONJON-DRAGON; and a system-scale code used for thermal-hydraulic simulations. Efficient data exchange among these codes is performed within computer memory by using the MED libraries, provided by the SALOME platform.

]]> Scipedia content https://www.scipedia.com/public/Tubita_et_al_2021a Mon, 12 Jul 2021 08:37:41 +0200 https://www.scipedia.com/public/Tubita_et_al_2021a <![CDATA[Effect of fretting-wear on dynamic analysis. Comparison between experimental results and numerical simulations for a vibratory friction rig.]]> Dry friction in contact interfaces can have an important impact on the dynamic response of jointed structures subjected to vibration. It may cause frettingwear leading to a modification of the contact surface geometry by producing wear debris through material removal and dissipating energy. Consequently, the contact behaviour is modified and the worn geometry induces a change in vibrations level. Therefore, it is important to be able to simulate these complex phenomena occurring at the interfaces to predict the forced response of assembled structures and also their life-expectancy to design high confidence components. A multi-scale approach is implemented considering a slow-scale for wear phenomena and a fast-scale for the non-linear dynamic response and applied to validate an experimental test.

]]> Scipedia content https://www.scipedia.com/public/Onishi_Ishihara_2021a Mon, 12 Jul 2021 08:37:34 +0200 https://www.scipedia.com/public/Onishi_Ishihara_2021a <![CDATA[Computational Fluid-Structure Interaction Framework for Simulating Characteristic Deformations in Insect Flapping Wings]]> In this study, a computational fluid­structure interaction (FSI) framework for characteristic deformations in insect's wings is proposed. The proposed framework consists of a pixel wing model using a structured shell finite element mesh, a projection method for the monolithic FSI monolithic equations using an algebraic splitting, and the FSI dynamic similarity law to measure dynamic similarity between model's and actual insect's flights. It is shown that the proposed framework can directly simulate passive feathering and cambering in insect's wings caused by the FSI, whose magnitudes are very close to those of actual insects.

]]> Scipedia content https://www.scipedia.com/public/Giovacchini_et_al_2021a Mon, 12 Jul 2021 08:37:26 +0200 https://www.scipedia.com/public/Giovacchini_et_al_2021a <![CDATA[Thermal-hydraulic and neutronic codes coupling for the analysis of a Lead Fast Reactor]]> In this work the thermal-hydraulics and neutronics behavior of a Lead Fast Reactor (LFR) core is investigated evaluating the power generation distribution taking into account the local temperature field. The temperature field is evaluated using the CFD finite element code FEMuS and exchanged with the multiscale neutron code DONJON-DRAGON, which interpolates the macroscopic cross-sections according to the local temperature field and local lead density distribution. As a result, the neutron flux changes and defines a new power density distribution which is used to update the temperature field into the CFD code. The coupling between neutron and CFD codes is achieved through their inclusion into the numerical platform SALOME. The numerical libraries MED, included into the SALOME platform, are used to exchange data run-time between FEMuS and DONJON.

]]> Scipedia content https://www.scipedia.com/public/Ficini_et_al_2021a Mon, 12 Jul 2021 08:37:16 +0200 https://www.scipedia.com/public/Ficini_et_al_2021a <![CDATA[Uncertainty Quantification of an Autonomous Surface Vehicle by Multi-fidelity Surrogate Models]]> A multi-fidelity Gaussian process (MF-GP) is presented for the forward uncertainty quantification (UQ) of the performance of an autonomous surface vehicle (ASV) subject to uncertain operating conditions. The ASV is a shallow water autonomous multipurpose platform (SWAMP), designed for the acquisition of the environmental parameters in the extremely shallow waters of wetlands. The quantity of interest (QoI) is the hydrodynamic resistance of the SWAMP subject to variable payload and longitudinal position of its center of mass. The QoI is assessed by a linear potential-flow solver coupled with the rigid body equations of motion. Multiple fidelity levels are defined based on the computational grid size and the level of coupling between hydrodynamic loads and motions. The MF-GP is based on a low-fidelity surrogate, corrected with an additive function, representing the error between higher and lower fidelity solutions. The MF-GP provides the prediction with the associated uncertainty. The latter is used to adaptively train the MF-GP, adding points where the prediction uncertainty is maximum. Finally, the UQ of the QoI is performed by Monte Carlo sampling on the MF-GP surrogate. The first four statistical moments, the 95th percentile, and the probability density function of the QoI are assessed. MF-GP is compared to its single-fidelity (high-fidelity based) counterpart, showing overall better results.

]]> Scipedia content https://www.scipedia.com/public/Cocco_et_al_2021a Mon, 12 Jul 2021 08:37:06 +0200 https://www.scipedia.com/public/Cocco_et_al_2021a <![CDATA[Coupled multibody-mid fidelity aerodynamic solver for tiltrotor aeroelastic simulation]]> This paper proposes a new aeroelastic solution applicable to fixed and rotarywing aircraft by joining the multibody solver MBDyn and the mid-fidelity aerodynamic tool DUST, through the partitioned multi-physics coupling library preCICE. The coupled MBDyn-DUST simulation environment is intended for the evaluation of performance, loads, and vibratory levels of aircraft of unconventional configuration, such as tiltrotors, during critical transient maneuvers, and to perform aeroelastic stability assessment. The coupling has been tested and validated using simple aeroelastic models available in the literature, and subsequently used to simulate a tiltrotor roll maneuver in airplane mode.

]]> Scipedia content https://www.scipedia.com/public/Rohan_Lukes_2021a Mon, 12 Jul 2021 08:36:59 +0200 https://www.scipedia.com/public/Rohan_Lukes_2021a <![CDATA[Multiscale modelling of flow due to the peristaltic wave in deforming poro-piezoelectric medium]]> The paper reports on the homogenization based modelling of fluid saturated poroelastic materials containing locally controlable piezoelectric (PZ) actuators. This option provides metamaterial properties which enable to convert the electric power into the fluid transport due to the peristaltic deformation wave induced by the propagating voltage wave. A quasi-linear PZ-poroelastic material model is proposed to respect dependence of the effective medium parameters on the deformation at the microstructure (pore) level. Due to the sensitivity analysis of the homogenized coefficient, the two-scale modelling avoids any need to update the local microconfigurations. Numerical studies has been performed as the proof of the concept.

]]> Scipedia content https://www.scipedia.com/public/Ramegowda_Ishihara_2021a Mon, 12 Jul 2021 08:36:52 +0200 https://www.scipedia.com/public/Ramegowda_Ishihara_2021a <![CDATA[Hierarchically decomposed finite element method for the coupled four fields of the fluid-structure–piezoelectric–circuit interaction]]> A partitioned iterative method based on hierarchical decomposition is proposed for providing numerical modeling and analysis of the piezoelectric energy harvester which is involved in coupled fluid-structure interaction, coupled electro-mechanical, and a controlling electrical circuit for piezoelectric structural applications in energy harvesting. This circuitintegrated piezoelectric structural application in energy harvesting surrounded by fluid media takes the form of natural four-way coupling of fluid flow, the structure, the electromechanical effect of the piezoelectric material, and the electrical circuit. This can be formulated exactly as a fluid-structure-piezoelectric-circuit interaction. These coupled four fields are hierarchically decomposed into the fluid-structure interaction, structure-piezoelectric interaction, and piezoelectric-circuit interaction interactions. Then these subsystems are decomposed into each field. The proposed finite element method enables to reuse of existing techniques because of its modularity. Furthermore, scalability to multiphysics and multisystem couplings is expected. There are some numerical approaches in particular monolithic coupling methods are studied which are computationally expensive and leads to an ill-conditioned coefficient matrix. Nevertheless, accurate modeling for predicting the characteristics of this four-way coupling using partitioned methods has not yet been developed. This method enables an investigation of piezoelectric structures in fluid with complex geometry, material composition, and attached electrical circuits to the harvester. A flexible piezoelectric bimorph harvester in the converging channel is analyzed to demonstrate the efficiency of the proposed method. The results indicate that the method captures the coupled effect accurately.

]]> Scipedia content https://www.scipedia.com/public/Bucher_et_al_2021a Mon, 12 Jul 2021 08:36:44 +0200 https://www.scipedia.com/public/Bucher_et_al_2021a <![CDATA[Realizing CoSimulation in and with a multiphysics framework]]> Simulating coupled problems using a multiphysics framework is different from the classical approach using dedicated coupling tools. It can have several advantages such as reduced memory footprint or more efficient communication between the involved solvers. The realization of coupled simulations with a multiphysics framework is presented together with important details of the software design such as data management, data communication, mapping, and distributed computing. Several examples from different physical disciplines with coupling internal and external solvers are shown.

]]> Scipedia content https://www.scipedia.com/public/Gjerde_Rognes_2021a Mon, 12 Jul 2021 08:36:36 +0200 https://www.scipedia.com/public/Gjerde_Rognes_2021a <![CDATA[A mixed framework for topological model reduction of coupled PDEs]]> In this work, we consider a set of mixed-dimensional PDEs that are used to model e.g. microcirculation, root water uptake and the flow of fluids in a reservoir perforated with wells. To be more precise, we consider here the Poisson equation posed in two distinct domains. The two are then coupled by the use of a filtration law. We show how the mixed framework is a natural setting for this problem, as it allows the two equations to be posed using global variables. Further, the applications we consider are characterized by a scale disparity between the two domains. With this in mind, we perform a physically motivated averaging of the coupling condition. This has the advantage of allowing the solution to be approximated using non-conforming, coarse meshes.

]]> Scipedia content https://www.scipedia.com/public/Bal_Meschke_2021a Mon, 12 Jul 2021 08:36:29 +0200 https://www.scipedia.com/public/Bal_Meschke_2021a <![CDATA[Adaptive two-phase Particle Finite Element model for soft soil excavations in partially saturated soils]]> A coupled solid velocity-water pressure (vp) Particle Finite Element (PFEM) formulation in conjunction with a hypoplastic model for sandy soils is presented. Large deformations of the soil and the ever-evolving topology of the ground free surface, key features characterizing the cutting tool-soil interaction, are efficiently captured via the PFEM. The utilization of a hypoplastic constitutive formulation allows for the realistic modeling of the non-linear behavior of the soil deformable skeleton. The hydromechanical description of the partially saturated soft soil is completed by incorporating the van Genuchten hydraulic model for the calculation of the Soil Water Retention Curve (SWRC) in combination with the Karman-Cozeni equation for the estimation of the soil permeability. Finally, computational simulations of tool-soil interaction performed in sand are compared against experiments and the capabilities of the proposed model are demonstrated.

]]> Scipedia content https://www.scipedia.com/public/Schmalfus_et_al_2021a Mon, 12 Jul 2021 08:36:19 +0200 https://www.scipedia.com/public/Schmalfus_et_al_2021a <![CDATA[Partitioned Coupling vs. Monolithic Block-Preconditioning Approaches for Solving Stokes-Darcy Systems]]> We consider the time-dependent Stokes-Darcy problem as a model case for the challenges involved in solving coupled systems. Keeping the model, its discretization, and the underlying numerics for the subproblems in the free-flow domain and the porous medium constant, we focus on different solver approaches for the coupled problem. We compare a partitioned coupling approach using the coupling library preCICE with a monolithic block-preconditioned one that is tailored to different formulations of the problem. Both approaches enable the reuse of already available iterative solvers and preconditioners, in our case, from theDuMuxframework. Our results indicate that the approaches can yield performance and scalability improvements compared to using direct solvers: Partitioned coupling is able to solve large problems faster if iterative solvers with suitable preconditioners are applied for the subproblems. The monolithic approach shows even stronger requirements on preconditioning, as standard simple solvers fail to converge. Our monolithic block preconditioning yields the fastest runtimes for large systems, but they vary strongly with the preconditioner configuration. Interestingly, using a specialized Uzawa preconditioner for the Stokes subsystem leads to overall increased runtimes compared to block preconditioners utilizing a more general algebraic multigrid. This highlights that optimizing for the non-coupled cases does not always pay off.

]]> Scipedia content https://www.scipedia.com/public/Spenke_et_al_2021a Mon, 12 Jul 2021 08:36:11 +0200 https://www.scipedia.com/public/Spenke_et_al_2021a <![CDATA[Performance Impact of the Newton Iterations per Solver Call in Partitioned Fluid-Structure Interaction]]> The cost of a partitioned fluid-structure interaction scheme is typically assessed by the number of coupling iterations required per time step, while ignoring the Newton loops within the nonlinear sub-solvers. In this work, we discuss why these singlefield iterations deserve more attention when evaluating the coupling's efficiency and how to find the optimal number of Newton steps per coupling iteration.

]]> Scipedia content https://www.scipedia.com/public/Lopez_et_al_2021b Mon, 12 Jul 2021 08:36:03 +0200 https://www.scipedia.com/public/Lopez_et_al_2021b <![CDATA[A Transonic Potential Solver with an Embedded Wake Approach using Multivalued Finite Elements]]> A potential transonic solver with an embedded wake is presented. The flow outside of attached boundary layers of streamlined bodies flying at high Reynold numbers can be assumed to be irrotational and isentropic. This assumption reduces the NavierStokes equations to a single scalar nonlinear partial differential equation, namely the full-potential equation (FPE). The FPE expresses the conservation of mass in terms of the velocity potential. In this work, the FPE is discretized using a standard Galerkin finite element method, and the nonlinear system of equations stemming from the discretization is solved using Newton's method. An artificial compressibility method is used to stabilize the problem in supersonic flow regions. This method prevents the Jacobian from becoming singular and allows capturing shock waves. To include the viscosity effects in the lift generation, a model for the trailing wake needs to be introduced. In the presented method, the wake is modeled as a straight surface in the free-stream direction. This assumption is relaxed allowing mass flux across the wake. To capture the discontinuity in the velocity potential across the wake, a multivalued element method is employed.This implicit description of the wake within the mesh presents an effective approach to perform fluidstructure interaction computations and apply aeroelastic optimization methods, where the position of the wake changes during consecutive iterations. The solver is implemented in Kratos Multi-Physics and verified for different angles of attack and free-stream conditions. Since the pressure does not change in the transverse direction of the boundary layer, the FPE yields accurate lift, induced drag, and moment computations.

]]> Scipedia content https://www.scipedia.com/public/Dietzsch_et_al_2021a Mon, 12 Jul 2021 08:35:55 +0200 https://www.scipedia.com/public/Dietzsch_et_al_2021a <![CDATA[Energy-momentum time integration of gradient-based models for fiber-bending stiffness in anisotropic thermo-mechanical continua]]> Accurate dynamic simulations of 3D fiber-reinforced materials in lightweight structures motivate our research activities. In order to accomplish this, the material reinforcement is performed by fiber rovings with a separate bending stiffness, which can be modelled by a second-order gradient of the deformation mapping (see Reference [10]). With an independent field for the gradient of the right Cauchy-Green tensor, we extend the thermoelastic Cauchy continuum for fiber-matrix composites with single fibers. In addition, we use accurate higherorder energy-momentum schemes in combination with mixed finite element methods to obtain numerically stable long-term dynamic simulations and locking free meshes. Therefore, we introduce additional independent fields of well-known as well as new mixed finite elements within a variational-based space-time finite element method and adapt it to the new material formulation. We use Cook's cantilever beam as representative numerical example. We primarily analyze the influence of the fiber bending stiffness as well as the spatial and time convergence up to cubic order, but also look at the influence of Fourier's heat conduction in the matrix and fiber families.

]]> Scipedia content https://www.scipedia.com/public/Caccia_Masarati_2021a Mon, 12 Jul 2021 08:35:48 +0200 https://www.scipedia.com/public/Caccia_Masarati_2021a <![CDATA[Coupling multi-body and fluid dynamics analisys with preCICE and MBDyn]]> The software library preCICE allows to connect single physics solvers to perform multiphysics cosimulations in a partitioned way. We interfaced preCICE with the multibody dynamics software MBDyn and assessed its performance with the set of well-known benchmarks proposed by Turek and Hron. The set-up consists of a laminar incompressible flow around a slender elastic object, which is suitable to be simulated via MBDyn beam elements connected to a cloud of interface points.

]]> Scipedia content https://www.scipedia.com/public/Gross_et_al_2021a Mon, 12 Jul 2021 08:35:40 +0200 https://www.scipedia.com/public/Gross_et_al_2021a <![CDATA[Variational computational modelling of dynamical behaviour of fiber roving composites with inelastic anisotropic continua and thermomechanical coupling]]> The nonlinear finite element method is a computational method in the variational simulation of material models for materials with and without microstructures [1]. Taking into account microstructures of engineering materials in their computational models is often worthwhile to improve numerical predictions [2]. An example is the modelling of fiber-reinforced materials, which are manufactured on the microscale by filaments or on the mesoscale by rovings, respectively. A macroscopic finite element simulation of both materials provides an anisotropic continuum model. However, fiber-reinforced materials based on rovings demand for continua with extended kinematics. A computational modelling of extended continua is possible by a mixed finite element method. In this contribution, we show the introduction of internal rotational degrees of freedom to model also a stiffness with respect to roving flexure and twist. Furthermore, a corresponding structure-preserving time integration is obtained. Numerical examples also demonstrate the additional continuum stiffness owing to the consideration of roving flexure and twist.

]]> Scipedia content https://www.scipedia.com/public/Kolb_Schafer_2021a Mon, 12 Jul 2021 08:35:34 +0200 https://www.scipedia.com/public/Kolb_Schafer_2021a <![CDATA[Numerical Study on the Fluid-Structure Interaction and Aerodynamic Noise Radiation of a Membrane Airfoil.]]> This paper investigates the fuid-structure interaction phenomena and their effect on the aerodynamic noise radiation observed for a membrane airfoil subjected to a turbulent flow at a fixed angle of attack α= 20° . For this purpose, two cases with different Reynolds numbers (Re = 53,100 and Re = 79,700) are simulated. The applied partitioned fluid-structure interaction approach uses large eddy simulations to predict the incompressible flow problem and includes geometric non-linear effects for the structural problem. Following a hybrid method based on a hydrodynamic/acoustic splitting technique, the incompressible flow field solution provides the acoustic source term for the aeroacoustic computation. The results suggest a coupling between the vortex shedding, the dynamic structural response and the radiated aerodynamic sound for this configuration.

]]> Scipedia content https://www.scipedia.com/public/Takahashi_2021a Mon, 12 Jul 2021 08:35:27 +0200 https://www.scipedia.com/public/Takahashi_2021a <![CDATA[Numerical Simulation of Fluid-Structure Interaction for Thin Flat Delta Wing at Transonic Speed based on Opensource Software]]> The flutter of a thin flat-delta wing at transonic speed was investigated by fluid-structure interaction (FSI) analysis, which is based on the open-source software. The analysis model was composed of fluid solver SU2, structure solver CalculiX, and coupler preCICE library. The FSI coupling of both solvers was performed in a partitioned approach. The software and libraries were built on a cloud computing system in Hokkaido University. It was found that self-induced oscillation of the delta wing is induced by the shock wave and elastic deformation in the transonic regime.The primary frequency of the oscillation was approximately 20 Hz for all speeds considered herein. However, the eigenfrequencies of the present condition of the delta wing, which are 9.62, 36.69, 51.22, 88.94, etc., did not correspond to the oscillation frequency. The phase delay of aerodynamic force for the deformation of the delta wing appeared in the oscillation. It was indicated that the oscillation is amplified by the aerodynamic force at the low deformation phase, and that is attenuated at a high deformation phase. In other words, in one cycle, the wing is in an unstable state by receiving the energy from fluid flow at the low deformation and is in a stable state by passing the energy to fluid flow at high deformation. When this energy transfer is equilibrated, the oscillation reaches the limit cycle. It was found that this behavior of the delta wing at the transonic speed is attributed to the shock wave and elastic deformation, i.e., coupling between flow and structure.

]]> Scipedia content https://www.scipedia.com/public/Caccia_et_al_2021a Mon, 12 Jul 2021 08:35:19 +0200 https://www.scipedia.com/public/Caccia_et_al_2021a <![CDATA[Multi-physics Simulations of a Wind Turbine in Icing Conditions]]> Wind turbines in cold climates are likely to suffer from icing events, deteriorating the aerodynamic performances of the blades and decreasing their power output. In this work, a 3-hour rime ice accretion event is numerically simulated on five significant sections of a wind turbine blade operating in steady wind using a high-fidelity procedure based on the Blade Element Momentum Theory. The onshore NREL 5MW reference wind turbine is studied. Ice accretion is simulated through a fine multi-step process, adding ice layers approximately 0.5 mm thick; each step consists of the successive coupling of a CFD simulation, a Lagrangian particle-tracking of the cloud droplets, an ice accretion step, and re-meshing of the new geometry. Ice roughness is modelled with an equivalent sand-grain approach. After computing the aerodynamic coefficients of ice-contaminated airfoils, power losses are obtained considering the aeroelastic response of the wind turbine in turbulent winds as defined by the Design Load Case 1.1. The effect of the extension of roughness on the surface of the blade is also assessed. In the considered operating conditions and accretion times, a strong dependence between the decrease in power output and the tip-speed ratio and a small dependence on surface roughness are found.

]]> Scipedia content https://www.scipedia.com/public/Donizetti_et_al_2021a Mon, 12 Jul 2021 08:35:11 +0200 https://www.scipedia.com/public/Donizetti_et_al_2021a <![CDATA[A level-set based mesh adaptation technique for mass conservative ice accretion in unsteady simulations]]> This paper presents an innovative approach to model evolving boundaries problems due to the accumulation or erosion of material over a surface, offering a robust alternative to standard algebraic methods. The strategy is based on the level-set method and it allows the local conservation of the prescribed mass material accounting for the curvature of the body. No partial differential equations are solved for the level-set function, but simple geometric quantities are used to provide an implicit discretization of the new updated boundary. The method is applied to body-fitted unstructured grids, that allow a good representation of arbitrarily complex geometries. Two multi-step in-flight ice accretion simulations over a NACA0012 are presented to show the feasibility and adaptability of the method, that can be also extended to three-dimensional applications.

]]> Scipedia content https://www.scipedia.com/public/Baldan_et_al_2021a Mon, 12 Jul 2021 08:35:04 +0200 https://www.scipedia.com/public/Baldan_et_al_2021a <![CDATA[Efficient parallel algorithms for coupled fluid-particle simulation]]> Coupled fluid-particle simulations are routinely used in a variety of applications, ranging from respiratory droplet spreading to internal combustion engines, from ink-jet printing to in-flight ice accretion. The efficiency of parallel algorithms to simulate fluid-particle systems is strongly influenced by the different evolution of the flow and the particles dynamics. Indeed, a domain partitioning based on particle workload is possibly sub-optimal in terms of the number of fluid volume elements associated to each process. In this work, an efficient mesh partitioning based on graph representation is implemented. It can handle unstructured hybrid meshes composed by triangles and quadrilaterals in two spatial dimensions, and by tetrahedra, hexahedra, prisms, and pyramids in three dimensions. In order to obtain a domain decomposition to efficiently follow the particle trajectories, a preliminary solution is computed to suitably tag the fluid domain cells. The obtained weights represent the element probabilities to be crossed by particles. The algorithm is implemented using MPI distribute memory environment. The proposed approach is tested against reference cases for the coupled flow-particle simulation of ice accretion over 2D and 3D geometries. Two different cloud droplet impact test cases have been simulated: a NACA 0012 wing section and a NACA 64A008 swept horizontal tail. The computed collection efficiency compares fairly well with reference numerical and experimental data. The parallel efficiency of the algorithm is verified on a distributed memory cluster.

]]> Scipedia content https://www.scipedia.com/public/Manso_et_al_2021a Mon, 12 Jul 2021 08:34:55 +0200 https://www.scipedia.com/public/Manso_et_al_2021a <![CDATA[Discrete numerical modelling of single-particle crushing and oedometric tests, for different values of suction]]> Particle breakage plays an important role in rockfill mechanical behaviour. Under compression or shear, the crushing of particles modifies the grain size distribution and indirectly, the material permeability, their frictional properties and the corresponding critical state. In order to study the breakage of individual particles, several approaches were adopted using discrete element method (DEM). Some considered sub-particles joined by bonding or cohesive forces, other replaced particles, which verified a predefined failure criterion, by an equivalent group of smaller particles. In this paper, using the discrete element method, a new methodology was developed. It consisted of modelling crushable rockfill particles using the clump logic, which was responsible for providing a statistical and spatial variability in the strength and shape of the particles. Particle movements and interactions were determined using DEM, allowing to determined the deformation of the rockfill material. Clumps have a major advantage of severely decreasing the number of contact equations to be solved in the model, resulting in less computer time. A comprehensive study of the brittle failure of single-particle crushing tests is presented. Preliminary tests on particle size evolution were also performed, assuming some simplifications. No attempt was made to simulate the real particle size distribution (PSD), due to the cost of simulating smaller particles. Single-particle crushing tests and oedometer tests were simulated using crushable particles, whose results were in agreement with experimental data.

]]> Scipedia content https://www.scipedia.com/public/Shimada_et_al_2021a Mon, 12 Jul 2021 08:34:45 +0200 https://www.scipedia.com/public/Shimada_et_al_2021a <![CDATA[Eulerian Formulation Using Lagrangian Marker Particles with Reference Map Technique for Fluid-structure Interaction Problem]]> Full Eulerian methods constitute a family of numerical techniques used to simulate fluid-structure interaction problems. In a full Eulerian method, the velocity gradient tensor is used to compute deformation of solid. However, it is difficult to compute solid stress accurately near the interface, where the velocity between fluid and solid changes drastically. In this work, we propose an Eulerian formulation for fluid-structure interaction problems using Lagrangian marker particles with the Reference Map Technique to compute the deformation of solid accurately near material interfaces without using the gradient of the velocity. We illustrate and validate the proposed method through the presentation of various benchmark problems.

]]> Scipedia content https://www.scipedia.com/public/Akishin_et_al_2021a Mon, 12 Jul 2021 08:34:37 +0200 https://www.scipedia.com/public/Akishin_et_al_2021a <![CDATA[Solution of Electromagnetic Problem for an Application in Advanced Pultrusion Processes]]> To demonstrate features and benefits of electromagnetic energy source, the heating of rod profile made of polyester resin POLRES 305BV and glass fibres 4800 tex in cylindrical cavity resonator was studied. Materials with different dielectric properties: zirconium dioxide, boron nitride and quartz glass for a microwave transparent die were selected and analysed. The optimal diameter of ceramic die providing an effective and uniform electric field in the composite profile was found for each material.

]]> Scipedia content https://www.scipedia.com/public/Xiaochuang_et_al_2021a Mon, 12 Jul 2021 08:34:29 +0200 https://www.scipedia.com/public/Xiaochuang_et_al_2021a <![CDATA[Simulating water and soil gushing around shield tunnel with Material Point Method]]> In recent years, serious accidents due to sand and water gushing around shield tunnel happen from time to time. Sand and water gushing could lead to large soil displacement, change soil stress field around tunnels, and then threaten the safety of tunnel structures. To date, there is a lack of theoretical research on the evolution of sand and water gushing, and the numerical simulation of the process is challenging because soil-water interaction, soil-structure interaction and large deformations have to be accounted for. In this paper, the Material Point Method (MPM) is used to deal with large deformation and various simulation cases considering different gushing locations at tunnels are carried out to investigate the development of soil displacement and stress around tunnels due to water and soil gushing. The results show that position of the gushing point greatly affect the damage scope. The sand gushing rate, the soil displacement and stress field, the ground settlement trough, and the earth pressure on the tunnel linings develop completely differently due to the varying position of the gushing point, which are analyzed to suggest reasonable guidance and countermeasures for preventing future sand and water gushing accidents.

]]> Scipedia content https://www.scipedia.com/public/Ghorbani_Kodikara_2021a Mon, 12 Jul 2021 08:31:19 +0200 https://www.scipedia.com/public/Ghorbani_Kodikara_2021a <![CDATA[Elastoplastic indentation of unsaturated soils using a rigid cylinder]]> We develop a fully coupled finite element solution for elastoplastic indentations of unsaturated granular soils by a rigid cylinder by using a mortar-type contact algorithm. In the presented solution, we have employed an advanced constitutive model that allows the inclusion of the effect of matric suction and induced anisotropy in the problem. Several numerical examples in both static and dynamic scenarios are provided for validation and demonstrating the capabilities of the presented framework.

]]> Scipedia content https://www.scipedia.com/public/Sautter_et_al_2021a Mon, 12 Jul 2021 08:23:15 +0200 https://www.scipedia.com/public/Sautter_et_al_2021a <![CDATA[Coupling the Discrete Element Method with the Finite Element Method to Simulate Rockfall Impact Experiments]]> To numerically simulate rockfall impact on flexible protection structures two different numerical methods are coupled within the open-source multi-physics code KRATOS. The impacting object is modeled with the help of a cluster of spherical discrete elements and its movement and contact forces are simulated using the Discrete Element Method (DEM). To realize a partitioned coupling simulation the contact forces are subsequently transferred to the light-weight protection structure which is analyzed and simulated using the Finite Element Method (FEM). To allow a stable simulation even in the case of large contact forces and/or large time steps a strong coupling GaussSeidel algorithm is presented. Subsequently the applicability of the method is shown by calculating experiments and finally the inclusion of digital terrain data is demonstrated.

]]> Scipedia content https://www.scipedia.com/public/Begum_et_al_2021a Fri, 09 Jul 2021 15:33:26 +0200 https://www.scipedia.com/public/Begum_et_al_2021a <![CDATA[Finite Element Methods for the simulation of thixotropic flow problems]]> This note is concerned with the application of Finite Element Methods (FEM) and Newton-Multigrid solvers for the simulation of thixotropic flow problems. The thixotropy phenomena are introduced into viscoplastic material by taking into account the internal material micro structure using a scalar structure parameter. Firstly, the viscoplastic stress is modified to include the thixotropic stress dependent on the structure parameter. Secondly, an evolution equation for the structure parameter is introduced to induce the time-dependent process of competition between the destruction (breakdown) and the construction (buildup) inhabited in the material. Substantially, this is done simply by introducing a structure-parameter-dependent viscosity into the rheological model for yield stress material. The modified thixotropic viscoplastic stress w.r.t. the structure parameter is integrated in quasi-Newtonian manner into the generalized Navier-Stokes equations and the evolution equation for the structure parameter constitutes the main core of full set of modeling equations, which are creditable as the privilege answer to incorporate thixotropy phenomena. A fully coupled monolithic finite element approach has been exercised which manages the material internal micro structure parameter, velocity, and pressure fields simultaneously. The nonlinearity of the corresponding problem, related to the dependency of the diffusive stress on the material parameters and the nonlinear structure parameter models on the other hand, is treated with generalized Newton's method w.r.t. the Jacobian's singularities having a global convergence property. The linearized systems inside the outer Newton loops form a typical saddle-point problem which is solved using a geometrical multigrid method with a Vanka-like smoother taking into account a stable FEM approximation pair for velocity and pressure with discontinuous linear pressure and biquadratic velocity spaces. We examine the accuracy, robustness and efficiency of the Newton-Multigrid FEM solver throughout the solution of thixotropic viscoplastic flow problems in Couette device and in 4:1 contraction.

]]> Scipedia content https://www.scipedia.com/public/Kumar_et_al_2021a Fri, 09 Jul 2021 15:21:02 +0200 https://www.scipedia.com/public/Kumar_et_al_2021a <![CDATA[Design and Analysis of Fast and Zero Voltage Switching Of Interleaved Flyback Converter with H6 Type Inverter for Photovoltaic Applications]]> A design and load analysis of interleaved flyback converter with H6 inverter topology is proposed. Flyback converter is one among the DC-DC converter with high frequency which is used or low power applications. Because of high frequency operation switching losses and stresses are more. To reduce stresses and losses across the switch of interleaved flyback converter is proposed. In the grid tied inverter system leakage current is one of the disadvantages and to avoid this H6 type inverter is used. With this advantage of H6 inverter and flyback converter this paper is mainly focused on stresses across switches and eliminating leakage current, harmonic reduction. Further the fast switching is proposed within converter in order to deliver maximum power transfer delivered to load through grid. To validate the overall performance the proposed converter modeled in MATLAB-SIMULINK and prototype developed using DSP DSP TMS320F28377S and connected to grid connected load.

]]> Arulmozhiyal R https://www.scipedia.com/public/Mishra_2020b Thu, 08 Jul 2021 20:51:02 +0200 https://www.scipedia.com/public/Mishra_2020b <![CDATA[MACHINE LEARNING CLASSIFICATION MODELS FOR DETECTION OF THE FRACTURE LOCATION IN DISSIMILAR FRICTION STIR WELDED JOINT]]> Data analysis is divided into two categories i.e. classification and prediction. These two categories can be used for extraction of models from the dataset and further determine future data trends or important set of classes available in the dataset. The aim of the present work is to determine location of the fracture failure in dissimilar friction stir welded joint by using various machine learning classification models such as Decision Tree, Support Vector Machine (SVM), Random Forest, Naïve Bayes and Artificial Neural Network (ANN). It is observed that out of these classification algorithms, Artificial Neural Network results have the best accuracy score of

]]> Akshansh Mishra https://www.scipedia.com/public/Mishra_2021b Thu, 08 Jul 2021 19:22:04 +0200 https://www.scipedia.com/public/Mishra_2021b <![CDATA[Contrast Limited Adaptive Histogram Equalization (CLAHE) Approach for Enhancement of the Microstructures of Friction Stir Welded Joints]]> Image processing algorithms are finding various applications in manufacturing and materials industries such as identification of cracks in the fabricated samples, calculating the geometrical properties of the given microstructure, presence of surface defects, etc. The present work deals with the application of Contrast Limited Adaptive Histogram Equalization (CLAHE) algorithm for improving the quality of the microstructure images of the Friction Stir Welded joints. The obtained results showed that the obtained value of quantitative metric features such as Entropy value and RMS Contrast value were high which resulted in enhanced microstructure images.

]]> Akshansh Mishra https://www.scipedia.com/public/Reese_et_al_2021a Thu, 08 Jul 2021 11:49:57 +0200 https://www.scipedia.com/public/Reese_et_al_2021a <![CDATA[Efficient data structures for data-driven mechanics]]> The data-driven computing paradigm initially introduced by Kirchdoerfer & Ortiz (2016) enables finite element computations in solid mechanics to be performed directly from material data sets. From the point of view of computational effort, the most challenging task is the projection of admissible states at material points onto their closest states in the material data set. In this study, we compare and develop several possible data structures for solving this nearest-neighbor problem. We show that approximate nearest-neighbor algorithms can accelerate material data searches by several orders of magnitude relative to exact searching algorithms. The approximations are suggested by—and adapted to—the structure of the datadriven iterative solver and result in no significant loss of solution accuracy. The performance of the nearest-neighboralgorithmsare assessed with respect to material data set size at the example of 3D elasticity and elasto-plasticity test cases. We show that computations including up to one billion material data points on a single processor are feasible within a few seconds execution time.

]]> Scipedia content https://www.scipedia.com/public/Sa_Behrendt_2021a Wed, 07 Jul 2021 17:06:02 +0200 https://www.scipedia.com/public/Sa_Behrendt_2021a <![CDATA[WP3 "Design and Engineering for Vessel Production Improvement" and WP4 "Smart manufacturing approach for developing shipyard 4.0 strategy"]]> The main objective of FIBRE4YARDS project is to maintain European global leadership in ship building and ship maintenance, through implementation of the Shipyard 4.0 concept in which advanced and innovative FRP manufacturing technologies are successfully introduced.

This project has received funding from European Union's Horizon 2020 research and innovation programme under grant agreement n°101006860.

]]> Dominika Behrendt https://www.scipedia.com/public/Dolz_Behrendt_2021a Wed, 07 Jul 2021 17:02:02 +0200 https://www.scipedia.com/public/Dolz_Behrendt_2021a <![CDATA[FIBRE4YARDS: Current State & Interests Of EU Shipyards In Composite Production Processes]]> The main objective of FIBRE4YARDS project is to maintain European global leadership in ship building and ship maintenance, through implementation of the Shipyard 4.0 concept in which advanced and innovative FRP manufacturing technologies are successfully introduced.

This project has received funding from European Union's Horizon 2020 research and innovation programme under grant agreement n°101006860.

]]> Dominika Behrendt https://www.scipedia.com/public/Behrendt_2021a Wed, 07 Jul 2021 16:57:16 +0200 https://www.scipedia.com/public/Behrendt_2021a <![CDATA[New Production Processes to be implemented in the Project]]> The main objective of FIBRE4YARDS project is to maintain European global leadership in ship building and ship maintenance, through implementation of the Shipyard 4.0 concept in which advanced and innovative FRP manufacturing technologies are successfully introduced.

This project has received funding from European Union's Horizon 2020 research and innovation programme under grant agreement n°101006860.

]]> Dominika Behrendt https://www.scipedia.com/public/Martinez_Behrendt_2021b Wed, 07 Jul 2021 16:52:02 +0200 https://www.scipedia.com/public/Martinez_Behrendt_2021b <![CDATA[Fibre Composite Manufacturing Technologies for the Automation and Modular Construction in Shipyards, Project Overview]]> The main objective of FIBRE4YARDS project is to maintain European global leadership in ship building and ship maintenance, through implementation of the Shipyard 4.0 concept in which advanced and innovative FRP manufacturing technologies are successfully introduced.

This project has received funding from European Union's Horizon 2020 research and innovation programme under grant agreement n°101006860.

]]> Dominika Behrendt https://www.scipedia.com/public/(as)_GARCIA_CURO_2021a Wed, 07 Jul 2021 07:57:02 +0200 https://www.scipedia.com/public/(as)_GARCIA_CURO_2021a <![CDATA[ESTRATEGIAS DE DIFERENCIACIÓN CON PERCEPCIÓN DEL VALOR EN LA RENTABILIDAD DE LOS NEGOCIOS DEL RUBRO DE REGALOS JUNÍN, PERÚ]]> GIANMARCO GARCIA CURO https://www.scipedia.com/public/Mishra_2021a Tue, 06 Jul 2021 06:59:03 +0200 https://www.scipedia.com/public/Mishra_2021a <![CDATA[Friction Stir Welding/Processing of High Entropy Alloys (HEAs)]]> The composition of High Entropy Alloys is quite different from the existing classical engineering alloys because in near equiatomic ratios they contain multiple principal alloying elements. Design and development of high entropy alloys is very important to overcome the shortcomings of conventionally used alloys in applications where operating conditions of temperature and loading are extreme. High entropy alloys generally find applications in compressor blades of an aerospace engine, energy, and transportation industries due to its low density and high strength. In order to enhance the application of high entropy alloys, the proper selection of a feasible welding process is very important. It has been observed that when high entropy alloys are subjected to the welding process other than the Friction Stir Welding process then it will result in reduced overall strength and lower hardness in the fusion zone and heat-affected zone. In this recent paper, the application of Friction Stir Welding for joining the high entropy alloys and also using Friction Stir Processing for improving the mechanical and microstructure properties of high entropy alloys are discussed.

]]> Akshansh Mishra https://www.scipedia.com/public/Pariente_2021c Mon, 05 Jul 2021 13:40:35 +0200 https://www.scipedia.com/public/Pariente_2021c <![CDATA[Design and engineering of two concepts of large Offshore Wind and Tindal Stream Platforms(OWTPs)]]> This presentation was held at the FIBREGY & FIBRE4YARDS joint info day on July 1st, 2021.

The main objective of FIBRE4YARDS project is to maintain European global leadership in ship building and ship maintenance, through implementation of the Shipyard 4.0 concept in which advanced and innovative FRP manufacturing technologies are successfully introduced. This project has received funding from European Union's Horizon 2020 research and innovation programme under grant agreement n°101006860.

]]> Jesús Sánchez Pinedo https://www.scipedia.com/public/Marques_2021b Mon, 05 Jul 2021 13:36:27 +0200 https://www.scipedia.com/public/Marques_2021b <![CDATA[Materials/Processes for the Turneable Turret (Reduced scale prototype by FW)]]> This presentation was held at the FIBREGY & FIBRE4YARDS joint info day on July 1st, 2021.

The main objective of FIBRE4YARDS project is to maintain European global leadership in ship building and ship maintenance, through implementation of the Shipyard 4.0 concept in which advanced and innovative FRP manufacturing technologies are successfully introduced. This project has received funding from European Union's Horizon 2020 research and innovation programme under grant agreement n°101006860.

]]> Jesús Sánchez Pinedo https://www.scipedia.com/public/Casals_2021b Mon, 05 Jul 2021 13:33:16 +0200 https://www.scipedia.com/public/Casals_2021b <![CDATA[Development and Validation of models for material degradation, strength assessment and structural health monitoring]]> This presentation was held at the FIBREGY & FIBRE4YARDS joint info day on July 1st, 2021.

The main objective of FIBRE4YARDS project is to maintain European global leadership in ship building and ship maintenance, through implementation of the Shipyard 4.0 concept in which advanced and innovative FRP manufacturing technologies are successfully introduced. This project has received funding from European Union's Horizon 2020 research and innovation programme under grant agreement n°101006860.

]]> Jesús Sánchez Pinedo https://www.scipedia.com/public/Marques_2021a Mon, 05 Jul 2021 13:00:33 +0200 https://www.scipedia.com/public/Marques_2021a <![CDATA[Materials/Processes for the Turneable Turret (reduced scale prototype by FW)]]> This presentation was held at the FIBREGY & FIBRE4YARDS joint info day on July 1st, 2021.

The overall objective of the FIBREGY project is to enable the extensive use of FRP materials in the structure of the next generation of large Offshore Wind and Tidal Power platforms. In order to achieve this objective, the project will develop, qualify and audit innovative FRP materials for offshore applications, elaborate new design procedures and guidelines, generate efficient production, inspection and monitoring methodologies, and validate and demonstrate advanced software analysis tools. Finally, the different developed technologies will be demonstrated by using advanced simulation techniques and building large and real-scale prototypes.

]]> Jesús Sánchez Pinedo https://www.scipedia.com/public/Pariente_2021b Mon, 05 Jul 2021 10:34:39 +0200 https://www.scipedia.com/public/Pariente_2021b <![CDATA[Design and engineering of two concepts of large Offshore Wind and Tidal Stream platforms (OWTPs)]]> This presentation was held at the FIBREGY & FIBRE4YARDS joint info day on July 1st, 2021.

The overall objective of the FIBREGY project is to enable the extensive use of FRP materials in the structure of the next generation of large Offshore Wind and Tidal Power platforms. In order to achieve this objective, the project will develop, qualify and audit innovative FRP materials for offshore applications, elaborate new design procedures and guidelines, generate efficient production, inspection and monitoring methodologies, and validate and demonstrate advanced software analysis tools. Finally, the different developed technologies will be demonstrated by using advanced simulation techniques and building large and real-scale prototypes.

]]> Jesús Sánchez Pinedo https://www.scipedia.com/public/Martinez_Behrendt_2021a Mon, 05 Jul 2021 10:29:03 +0200 https://www.scipedia.com/public/Martinez_Behrendt_2021a <![CDATA[FIBRE4YARDS]]> The main objective of FIBRE4YARDS project is to maintain European global leadership in ship building and ship maintenance, through implementation of the Shipyard 4.0 concept in which advanced and innovative FRP manufacturing technologies are successfully introduced.

This project has received funding from European Union's Horizon 2020 research and innovation programme under grant agreement n°101006860.

]]> Dominika Behrendt https://www.scipedia.com/public/Casals_2021a Mon, 05 Jul 2021 10:07:17 +0200 https://www.scipedia.com/public/Casals_2021a <![CDATA[Development and validation of models for material degradation, strength assessment and structural health monitoring]]> This presentation was held at the FIBREGY & FIBRE4YARDS joint info day on July 1st, 2021.

The overall objective of the FIBREGY project is to enable the extensive use of FRP materials in the structure of the next generation of large Offshore Wind and Tidal Power platforms. In order to achieve this objective, the project will develop, qualify and audit innovative FRP materials for offshore applications, elaborate new design procedures and guidelines, generate efficient production, inspection and monitoring methodologies, and validate and demonstrate advanced software analysis tools. Finally, the different developed technologies will be demonstrated by using advanced simulation techniques and building large and real-scale prototypes.

]]> Jesús Sánchez Pinedo https://www.scipedia.com/public/FIBREGY_Garcia-Espinosa_2021a Thu, 01 Jul 2021 17:33:02 +0200 https://www.scipedia.com/public/FIBREGY_Garcia-Espinosa_2021a <![CDATA[FIBREGY Leaflet]]> The overall objective of the project FIBREGY 'Development, engineering, production and life cycle management of improved FIBRE-based material solutions for the structure and functional components of large offshore wind enerGY and tidal power platforms' is to enable the extensive use of FRP materials in the structure of the next generation of large Offshore Wind and Tidal Power platforms. In order to achieve this objective, the project will develop, qualify and audit innovative FRP materials for offshore applications, elaborate new design procedures and guidelines, generate efficient production, inspection and monitoring methodologies, and validate and demonstrate advanced software analysis tools. Finally, the different developed technologies will be demonstrated by using advanced simulation techniques and building large and real-scale prototypes.

 

]]> Julio García-Espinosa https://www.scipedia.com/public/Draft_Garcia-Espinosa_494548278 Thu, 01 Jul 2021 17:06:03 +0200 https://www.scipedia.com/public/Draft_Garcia-Espinosa_494548278 <![CDATA[An Introduction to FIBREGY project]]> This presentation was held at the FIBREGY & FIBRE4YARDS joint info day on July 1st, 2021.

The overall objective of the FIBREGY project is to enable the extensive use of FRP materials in the structure of the next generation of large Offshore Wind and Tidal Power platforms. In order to achieve this objective, the project will develop, qualify and audit innovative FRP materials for offshore applications, elaborate new design procedures and guidelines, generate efficient production, inspection and monitoring methodologies, and validate and demonstrate advanced software analysis tools. Finally, the different developed technologies will be demonstrated by using advanced simulation techniques and building large and real-scale prototypes.

]]> Julio García-Espinosa https://www.scipedia.com/public/Almeida_2021a Thu, 01 Jul 2021 15:44:50 +0200 https://www.scipedia.com/public/Almeida_2021a <![CDATA[More Equilibrium, More Complementarity!]]> Scipedia content https://www.scipedia.com/public/Juarez_et_al_2021b Thu, 01 Jul 2021 09:28:12 +0200 https://www.scipedia.com/public/Juarez_et_al_2021b <![CDATA[Numerical Solution of the Cauchy Problem for the Laplace Equation: A Deterministic and Bayesian Approach]]> We consider a statistical inversion computational model with Gaussian distributions for the numerical solution of the Cauchy problem for the Laplace equation. The a priori model is built up from Gaussian Markov random fields. Different precision matrices for the Cauchy problem are introduced. We take advantage of the relationship between the a priori distribution and traditional Tikhonov regularization to propose different models where smooth and non-smooth regularization is possible. A low range analysis allow us to estimate the optimal dimension of data and its relation to the the unknown.

]]> Scipedia content https://www.scipedia.com/public/Ramirez_et_al_2021b Wed, 30 Jun 2021 05:39:02 +0200 https://www.scipedia.com/public/Ramirez_et_al_2021b <![CDATA[Implementing virtual laboratories: Remote teaching of electrical machines]]> One of the fundamental requirements of engineering education is laboratory work and practical teaching. The main purpose of the laboratory is to provide a space for students to carry out practices that allow them to check the theory learned in the classroom, validate hypotheses, propose solutions and recommendations, develop critical thinking skills and develop soft skills. The provision of laboratory work to engineering students helps them familiarize themselves with similar situations as they will find real life as they practice their profession. Primarily, this laboratory work is based on actual hardware and a laboratory where the students can work at a specified time, perform experiments under the guidance of a lab technician and leave with data that they can analyze later using the knowledge they learned in class. These laboratories and the hardware equipment in them are expensive to acquire and maintain. Also, they are an expensive upgrade, yet upgrading is inevitable with the rapid change in technology we are all experiencing. Various institutions have been forced to use outdated laboratory hardware or do with minimal hardware for performing engineering experiments. However, the rapid increase in technology that is contributing to the problem can be used to solve it by having a suitable front-end design in computers that can be used to simulate experiments.

]]> Sergio Rivera https://www.scipedia.com/public/Zee_et_al_2021a Mon, 28 Jun 2021 15:40:51 +0200 https://www.scipedia.com/public/Zee_et_al_2021a <![CDATA[Data-Driven Goal-Oriented Finite Element Methods: A~Machine-Learning Minimal-Residual (ML-MRes) Framework]]> We consider the data-driven acceleration of Galerkin-based finite element discretizations for the approximation of partial differential equations (PDEs). The aim is to obtain approximations on meshes that are very coarse, but nevertheless resolve quantities of interest with striking accuracy. Our work is inspired by the the machine learning framework of Mishra (2018), who considered the data-driven acceleration of finite-difference schemes. The essential idea is to optimize a numerical method for a given coarse mesh, by minimizing a loss function consisting of errors with respect to the quantities of interest for obtained training data. Our main contribution lies in the identification of a stable and consistent parametric family of finite element methods on a given mesh. In particular, we consider a general Petrov-Galerkin method, where the trial space is fixed, but the test space has trainable parameters that are to be determined in the offline training process. Finding the optimal test space therefore amounts to obtaining a goal-oriented discretization that is completely tailored for the quantity of interest. The Petrov-Galerkin method is equivalent to a Minimal-Residual formulation, as commonly studied in the context of DPG and optimal Petrov-Galerkin methods. As is natural in deep learning, we use an artificial neural network to define the family of test spaces, whose parameters are learned from the data. Using numerical examples for the Laplacian and advection equation, we demonstrate that the trained method has superior approximation of quantities of interest even on very coarse meshes. [1] I. Brevis, I. Muga, and K. G. van der Zee, A machine-learning minimal-residual (ML-MRes) framework for goal-oriented nite element discretizations, Computers and Mathematics with Applications, to appear, https://doi.org/10.1016/j.camwa.2020.08.012 (2020)

]]> Scipedia content https://www.scipedia.com/public/Draft_Content_221230245 Mon, 28 Jun 2021 15:40:01 +0200 https://www.scipedia.com/public/Draft_Content_221230245 <![CDATA[Prosthesis Optimization Using Contact Formulation in the Cartesian Grid Finite Element Method (cgFEM) Framework]]> Scipedia content https://www.scipedia.com/public/Garcia_et_al_2021a Mon, 28 Jun 2021 15:39:24 +0200 https://www.scipedia.com/public/Garcia_et_al_2021a <![CDATA[Stabilization of the Discontinuous Galerkin Formulation within the Cartesian Grid FEM]]> Scipedia content https://www.scipedia.com/public/Merli_et_al_2021a Mon, 28 Jun 2021 15:38:32 +0200 https://www.scipedia.com/public/Merli_et_al_2021a <![CDATA[Two-level Topology Optimization for High Definition Material Structures under the cgFEM Framework]]> Scipedia content https://www.scipedia.com/public/Ayoul-Guilmard_2021a Mon, 28 Jun 2021 12:39:02 +0200 https://www.scipedia.com/public/Ayoul-Guilmard_2021a <![CDATA[Analysis of stochastic gradient methods for PDE-constrained optimal control problems with uncertain parameters]]> Quentin Ayoul-Guilmard https://www.scipedia.com/public/Giusto_et_al_2021a Mon, 28 Jun 2021 08:05:01 +0200 https://www.scipedia.com/public/Giusto_et_al_2021a <![CDATA[Coupling Materials for Fluid-Structure Interactions in OpenFOAM]]> Scipedia content https://www.scipedia.com/public/Shaban_et_al_2021a Sat, 26 Jun 2021 17:49:46 +0200 https://www.scipedia.com/public/Shaban_et_al_2021a <![CDATA[Isogeometric Analysis of the UV Irradiation Curing Process in Additive Manufacturing]]> The photopolymerization-based additive manufacturing process, including 3D printing techniques such as stereolithography and digital light processing, has undergone considerable development over the last few decades. These techniques provide flexibility in the physical and chemical properties of 3D printed materials. The photopolymerization process is based on ultraviolet (UV) curing of liquid-state monomers/oligomers in the presence of photopolymerizable photoinitiators, which is known as the UV irradiation curing process. The UV light intensity has a significant effect on the reactivity and solidification process, modeling which has many challenges. In this work, we present a novel model that determines the required UV light intensity in the photopolymerization process. To make meaningful predictions of the UV light intensity influence on the curing process, it is essential to appropriately model the UV light waves. Maxwell’s equations are considered for this purpose. The photopolymerization process itself is described by the reaction-diffusion equation, which is coupled to Maxwell’s equations in a unit square of the resin. Isogeometric analysis is used to discretize the produced coupled system of equations. We present numerical results that demonstrate the light intensity influence on the UV curing process.

]]> Scipedia content https://www.scipedia.com/public/Ammouche_Jerusalem_2021a Sat, 26 Jun 2021 17:49:39 +0200 https://www.scipedia.com/public/Ammouche_Jerusalem_2021a <![CDATA[A Modular Nonlinear Stochastic Finite Element Formulation for Uncertainty Estimation]]> empty

]]> Scipedia content https://www.scipedia.com/public/Murugan_et_al_2021a Sat, 26 Jun 2021 17:49:31 +0200 https://www.scipedia.com/public/Murugan_et_al_2021a <![CDATA[Filament Path Optimization with Curvilinear Trajectories for Additive Manufacturing of Load-Bearing Components]]> empty

]]> Scipedia content https://www.scipedia.com/public/Garanzha_et_al_2021a Sat, 26 Jun 2021 17:49:24 +0200 https://www.scipedia.com/public/Garanzha_et_al_2021a <![CDATA[Moving Deforming Mesh Technique for Fluid Flow Simulation with Immersed Boundary Conditions]]> empty

]]> Scipedia content https://www.scipedia.com/public/Sherif_et_al_2021a Sat, 26 Jun 2021 17:49:16 +0200 https://www.scipedia.com/public/Sherif_et_al_2021a <![CDATA[Divergence-Free Extended Hybridizable Discontinuous Galerkin Method (X-HDG) For Laminar Incompressible Two-Phase Flow]]> empty

]]> Scipedia content https://www.scipedia.com/public/Freddi_Mingazzi_2021a Sat, 26 Jun 2021 17:49:09 +0200 https://www.scipedia.com/public/Freddi_Mingazzi_2021a <![CDATA[Energy Based Global-Local Strategies with Adaptive Mesh Refinement for the Phase-Field Approach to Brittle Fracture]]> This paper analyses different discretization procedures and compares their numerical performances in the solution of phase field approach to fracture problem. A predictor energetic principle is employed to determine the active regions where damage evolves and, by the usage of a global/local strategy, mesh adaptive refinement or a combination of the two techniques, smaller displacement and damage problems are solved. The computational costs of the simulations are therefore drastically reduced without lowering the accuracy of the results. Initially, the effectiveness and accuracy of the different strategies are analysed and compared. After, the effects of the active zones on the performance and precision of the results is investigated via a parametric analysis. Two different numerical examples are presented in order to validate and show the efficiency of the proposed optimization strategies in lowering the computational costs and CPU times required to perform the numerical simulations.

]]> Scipedia content https://www.scipedia.com/public/Fergoug_et_al_2021a Sat, 26 Jun 2021 17:49:01 +0200 https://www.scipedia.com/public/Fergoug_et_al_2021a <![CDATA[Model Error Estimation Based on Asymptotic Homogenization for Periodic Heterogeneous Structures]]> empty

]]> Scipedia content https://www.scipedia.com/public/Dave_et_al_2021a Sat, 26 Jun 2021 17:48:53 +0200 https://www.scipedia.com/public/Dave_et_al_2021a <![CDATA[Through-Thickness Water Transport and Hygro-Expansion in a Paper Sheet]]> empty

]]> Scipedia content https://www.scipedia.com/public/Nasika_et_al_2021a Sat, 26 Jun 2021 17:48:46 +0200 https://www.scipedia.com/public/Nasika_et_al_2021a <![CDATA[Enhancing Sensor Monitoring of Earthfill Dams Using Model Order Reduction]]> The scope of this work is to create a model to support a sensor monitoring system of a tailings dam. Such model can be used for monitoring and prediction, but also for the optimal design of the sensor network and the overall optimization of the monitoring system. To accelerate the model response we propose using Model Order Reduction techniques in the transient thermo- hydro-mechanical system. POD-based model reduction, combined with Discrete Empirical Interpolation (DEIM) is used for data assimilation applications, parameter identification (soil mechanical and hydraulic properties) and optimal sensor placement. The efficiency gains in inverse problem solving and the accuracy of the resulting ROM are examined and discussed.

]]> Scipedia content https://www.scipedia.com/public/Per_et_al_2021a Sat, 26 Jun 2021 17:48:38 +0200 https://www.scipedia.com/public/Per_et_al_2021a <![CDATA[Implicit shock tracking for unsteady flows by the method of lines]]> We present an extension of the recently developed high-order implicit shock tracking (HOIST) framework for resolving discontinuous solutions of inviscid, steady conservation laws. Using the method of lines, our schemes can handle unsteady flows with moving shocks, using time-accurate integration and moving meshes than align with the discontinuities. The techniques are demonstrated on various test problems with high-speed flow physics.

]]> Scipedia content https://www.scipedia.com/public/Rakotoarivelo_et_al_2021a Sat, 26 Jun 2021 17:48:29 +0200 https://www.scipedia.com/public/Rakotoarivelo_et_al_2021a <![CDATA[A New Conservative Remap Method for Discontinuous Numerical Fields]]> empty

]]> Scipedia content https://www.scipedia.com/public/Dobrev_et_al_2021a Sat, 26 Jun 2021 17:48:21 +0200 https://www.scipedia.com/public/Dobrev_et_al_2021a <![CDATA[Adaptive Tangential Relaxation and Surface Fitting for High-Order Mesh Optimization]]> empty

]]> Scipedia content https://www.scipedia.com/public/Hoffman_2021a Sat, 26 Jun 2021 17:48:15 +0200 https://www.scipedia.com/public/Hoffman_2021a <![CDATA[Adjoint Based Mesh Adaptation Techniques for Simulation of Turbulent Flow]]> In this paper we address the challenges of adjoint based mesh adaptation in the setting of industrial CFD, characterized by complex geometry and high Reynolds numbers. We use a space-time finite element discretization of the NS equations, and we focus on the challenges of massively parallel algorithms and the mathematical formulation of the NS equations.

]]> Scipedia content https://www.scipedia.com/public/Draft_Content_756198976 Sat, 26 Jun 2021 17:48:08 +0200 https://www.scipedia.com/public/Draft_Content_756198976 <![CDATA[DPG-Based Time-Marching-Schemes for Linear Parabolic and Hyperbolic PDEs]]> The Discontinuous Petrov-Galerkin (DPG) method with optimal test functions intends to approximate Partial Diff&#11;erential Equations (PDEs). It was introduced by Demkowicz and Gopalakrishnan in 2010. The main idea of this method is to select optimal test functions that guarantee the discrete stability of non-coercive problems. For that, they employ test functions that realize the supremum in the inf-sup condition. It has been previously applied to transient problems in the context of space-time formulations or together with &#12;nite diff&#11;erences in time. In this work, we follow the approach of applying the DPG method only in the time variable in order to obtain a DPG-based time-marching scheme for linear transient PDEs. For parabolic problems, we &#12;first semidiscretize in space by a classical Bubnov-Galerkin method and we consider an ultraweak variational formulation of the resulting system of Ordinary Di&#11;erential Equations (ODEs). Then, we calculate the optimal test functions analytically employing the adjoint norm. The optimal test functions we obtain are exponential-related functions of the sti&#11;ness matrix. Finally, we substitute the optimal test functions into the ultraweak variational formulation and we obtain the DPG-based time-marching scheme. Here, we obtain an independent formula for the trace variables and a system to locally compute the interiors of the elements. The procedure for hyperbolic problems is the same after reducing the equation to a fi&#12;rst order system. The equation we obtain for the trace variables is called variation-of-constants formula and it is the starting point of the so-called exponential integrators for solving systems of ODEs. In these type of methods, it is necessary to approximate the exponential of the sti&#11;ness matrix and related functions, called phi-functions. For the hyperbolic case, it is also possible to express the resulting system in terms of trigonometric functions. Although the theory of exponential integrators is classical, they have recently gained popularity due to the rise of the available software and e&#14;fficient algorithms to compute the action of function matrices over vectors. In our work, we express the DPG-based time-marching scheme in terms of the phi-functions for computational purposes. The main bene&#12;t of the presented method is that it &#12;ts into the DPG theory. Therefore, we can naturally apply adaptive strategies and a posteriori error estimation previously studied by the DPG community. Currently, most of the goal-oriented adaptive strategies for transient problems are based on Discontinuous Galerkin (DG) formulations in time because we need a variational formulation in time to represent the error in the quantity of interest over the whole space-time domain. Employing the variational formulation presented in this article, we will be able to design goal-oriented adaptive strategies in the future.

]]> Scipedia content https://www.scipedia.com/public/Valdes_et_al_2021a Sat, 26 Jun 2021 17:48:00 +0200 https://www.scipedia.com/public/Valdes_et_al_2021a <![CDATA[Data-Driven Identification for Linear-Viscoelastic Materials]]> Data-driven Identification (DDI) is a technique that allows to estimate the stresses of a sample and the behavior of the material solely by the use of strain information, avoiding the bias imposed by an empirical constitutive model. In this work, we extend the applicability of DDI from elasticity to linear-viscoelastic materials by extending the dimensionality of the problem. Rather than estimating the state of the elements considering an instantaneous value of strain-stress, we include the strain history of the sample in order to account for the viscosity effect. We also combine the method with data analysis techniques such as Kernel Principal Component Analysis to improve the estimation of stresses. Preliminary results in modeled samples show a clear improvement on the estimation of stresses when compared against the original formulation of the algorithm, allowing us to obtain results in cases where the original DDI fails to do so.

]]> Scipedia content https://www.scipedia.com/public/Dev_et_al_2021a Sat, 26 Jun 2021 17:47:53 +0200 https://www.scipedia.com/public/Dev_et_al_2021a <![CDATA[Compliant Mechanism Design with Stress constraint using Topology and Shape Optimization]]> empty

]]> Scipedia content https://www.scipedia.com/public/Duprez_et_al_2021a Sat, 26 Jun 2021 17:47:31 +0200 https://www.scipedia.com/public/Duprez_et_al_2021a <![CDATA[φ-FEM: a Finite Element Method on Domains Defined by Level-Sets]]> empty

]]> Scipedia content https://www.scipedia.com/public/Moradi_Shontz_2021a Sat, 26 Jun 2021 17:42:34 +0200 https://www.scipedia.com/public/Moradi_Shontz_2021a <![CDATA[A Multiobjective Optimization Approach to Untangling and Mesh Quality Improvement of Quadrilateral Meshes]]> In this talk, we present our multiobjective optimization approach to untangling and mesh quality improvement of quadrilateral meshes.

]]> Scipedia content https://www.scipedia.com/public/Castillo_Blatter_2021a Sat, 26 Jun 2021 17:42:27 +0200 https://www.scipedia.com/public/Castillo_Blatter_2021a <![CDATA[Modeling and Inversion 3D Electromagnetic Datasets on HPC Platforms]]> We present numerical results about electromagnetic modeling and inversion in the context of oil&gas and geothermal exploration. To perform numerical experiments, we use the PETGEM algorithm, which is an open-source parallel python electromagnetic modeler.

]]> Scipedia content https://www.scipedia.com/public/Ljung_et_al_2021a Sat, 26 Jun 2021 17:41:34 +0200 https://www.scipedia.com/public/Ljung_et_al_2021a <![CDATA[A Space-Time Multiscale Method for Parabolic Problems with Space- and Time-Dependent Coefficients]]> Presentation of a multiscale method, based on the framework of the localized orthogonal decomposition method, that deals with parabolic equations where the diffusion varies rapidly in both time and space.

]]> Scipedia content https://www.scipedia.com/public/Prudhomme_et_al_2021a Sat, 26 Jun 2021 16:54:29 +0200 https://www.scipedia.com/public/Prudhomme_et_al_2021a <![CDATA[Computational Analysis of Goal-Oriented Adaptive Strategies based on Several Error Representations]]> Scipedia content https://www.scipedia.com/public/Fang_Izzuddin_2021a Sat, 26 Jun 2021 16:53:40 +0200 https://www.scipedia.com/public/Fang_Izzuddin_2021a <![CDATA[Across-partition Contact Analysis with Adaptive Tracking]]> The current work proposes a novel adaptive node-to-surface contact approach to discretise the across-partition contact boundaries and to trace the evolution of contact locations for problems with across-partition contact boundaries.

]]> Scipedia content https://www.scipedia.com/public/He_et_al_2021a Sat, 26 Jun 2021 16:53:27 +0200 https://www.scipedia.com/public/He_et_al_2021a <![CDATA[Comparison of Shape Derivatives Using CUTFEM for ILL-Posed Bernoully Free Boundary Problem]]> Scipedia content https://www.scipedia.com/public/Cavaliere_et_al_2021a Sat, 26 Jun 2021 16:53:14 +0200 https://www.scipedia.com/public/Cavaliere_et_al_2021a <![CDATA[Nonintrusive Proper Generalized Decomposition Method for the Design Optimization of a Car]]> A model order reduction technique is proposed in order to optimise the design process of a car body structure with respect to the noise and vibration characteristics of the vehicle. The final goal is to support designers in the decision-making process, such that they can evaluate in real-time the impact of certain parameters on the global response of the structure.

]]> Scipedia content https://www.scipedia.com/public/Chetry_2021a Sat, 26 Jun 2021 16:52:35 +0200 https://www.scipedia.com/public/Chetry_2021a <![CDATA[Model Order Reduction for Viscoelastic Fluid Flows]]> Scipedia content https://www.scipedia.com/public/Kiran_et_al_2021a Sat, 26 Jun 2021 16:52:21 +0200 https://www.scipedia.com/public/Kiran_et_al_2021a <![CDATA[Model Order Reduction of Parametric Mechanical Problems Involving Contacts]]> In the context of manufacturing of engineering structures, unavoidable process variations can cause deviations in a manufactured structural part, resulting in “non-conformance” to the tolerance specifications. Prior to assembly, numerical simulations are often used to determine the effect of the non-conformances. Based on the analysis, parts with non-conformances are either accepted, rejected or reworked. However, the computational complexity of these numerical simulations delays the manufacturing schedule significantly. A real-time simulation tool, capable of evaluating the effect of non-conformances, is necessary to eliminate the bottleneck in the decision-making process. To accelerate the simulation of structural assemblies, we propose to apply model order reduction methods on mechanical problems involving non-linear contact interfaces. Reduction of contact problems involve a special challenge of solving a non-linear inequality constrained minimization problem, including a non-negativity condition on the contact pressure. Current approaches use mixed reduced bases for displacement and contact pressure fields, an orthogonal basis for displacement and a non-negative basis for contact pressure [1,2]. The contact pressure field is not linearly separable in nature. Hence, treating the contact problem as a low rank problem can reduce accuracy of the solution. We propose to resolve the linear inseparability using over-complete dictionaries along with sparse decomposition methods. The usage of sparse decomposition methods is inspired from the sparse behaviour observed in existing reduced approach. Sparse decomposition methods include methods like LASSO, Orthogonal Matching Projection, etc [3]. Sparse methods will be adapted to take into account inequality constraints, which are a crucial part of contact mechanics problems. REFERENCES [1] A. Benaceur, A. Ern and V. Ehrlacher, A reduced basis method for parametrized variational inequalities applied to contact mechanics. Intl. J. for Numerical Methods in Engg., 121(6), 1170–1197, 2019 [2] M. Balajewicz, D. Amsallem, & C. Farhat, Projection-based model reduction for contact problems. Intl. J. for Numerical Methods in Engineering, 106(8), 644–663, 2016 [3] J. Mairal, F. Bach, & J. Ponce, Sparse modeling for image and vision processing. Foundations and Trends in Computer Graphics and Vision, 8(2–3), 85–283, 2014

]]> Scipedia content https://www.scipedia.com/public/Maier_Verfurth_2021a Sat, 26 Jun 2021 16:52:08 +0200 https://www.scipedia.com/public/Maier_Verfurth_2021a <![CDATA[Multiscale Scattering in Nonlinear Kerr-Type Media]]> A multiscale approach for a nonlinear Helmholtz problem with possible oscillations in the Kerr coefficient, the refractive index, and the diffusion coefficient is presented. The method does not rely on structural assumptions on the coefficients and combines the multiscale technique known as Localized Orthogonal Decomposition with an adaptive iterative approximation of the nonlinearity. The method is rigorously analyzed in terms of well-posedness and convergence properties based on suitable assumptions on the initial data and the discretization parameters. Numerical examples illustrate the theoretical error estimates and underline the practicability of the approach.

]]> Scipedia content https://www.scipedia.com/public/Edel_et_al_2021a Sat, 26 Jun 2021 16:51:46 +0200 https://www.scipedia.com/public/Edel_et_al_2021a <![CDATA[Reduced Basis Method for Frequency Sweeps with Integral Equations Using Locally Adaptive Kernel Approximation]]> Scipedia content https://www.scipedia.com/public/Yago_et_al_2021a Wed, 23 Jun 2021 12:40:02 +0200 https://www.scipedia.com/public/Yago_et_al_2021a <![CDATA[Topology Optimization using the UNsmooth VARiational Topology OPtimization (UNVARTOP) method: an educational implementation in Matlab (preprint)]]> This paper presents an efficient and comprehensive MATLAB code to solve two-dimensional structural topology optimization problems, including minimum mean compliance, compliant mechanism synthesis and multi-load compliance problems. The Unsmooth Variational Topology Optimization (UNVARTOP) method, developed by Oliver et al. [22], is used in the topology optimization code, based on the finite element method (FEM), to compute the sensitivity and update the topology. The paper also includes instructions to improve the bisection algorithm, modify the computation of the Lagrangian multiplier by using an Augmented Lagrangian to impose the constraint, implement heat conduction problems and extend the code to three-dimensional topology optimization problems. The code, intended for students and newcomers in topology optimization, is included as an appendix (AppendixA) and it can be downloaded fromhttps://github.com/DanielYagotogether with supplementary material.

]]> María Jesús Samper https://www.scipedia.com/public/Roca_et_al_2021a Wed, 23 Jun 2021 12:19:03 +0200 https://www.scipedia.com/public/Roca_et_al_2021a <![CDATA[Multiresonant Layered Acoustic Metamaterial (MLAM) solution for broadband low-frequency noise attenuation through double-peak sound transmission loss response (preprint)]]> The problem of noise control and attenuation is of interest in a broad range of applications, especially in the low-frequency range, below 1000 Hz. Acoustic metamaterials allow us to tackle this problem with solutions that do not necessarily rely on high amounts of mass, however most of them still present two major challenges: they rely on complex structures making them difficult to manufacture, and their attenuating capabilities are limited to narrow frequency bandwidths. Here we propose the Multiresonant Layered Acoustic Metamaterial (MLAM) concept as a novel kind of acoustic metamaterial based on coupled resonances mechanisms. Their main advantages hinge on providing enhanced sound attenuation capabilities in terms of a double-peak sound transmission loss response by means of a layered configuration suitable for large scale manufacturing.

]]> María Jesús Samper https://www.scipedia.com/public/Raschi_et_al_2021a Wed, 23 Jun 2021 11:45:02 +0200 https://www.scipedia.com/public/Raschi_et_al_2021a <![CDATA[High performance reduction technique for multiscale finite element modeling (HPR-FE2): Towards industrial multiscale FE software (preprint)]]> The authors have shown in previous contributions that reduced order modeling with optimal cubature applied to finite element square (FE2) techniques results in a reliable and affordable multiscale approach, the HPR-FE2technique. Such technique is assessed here for an industrial case study of a generic 3D reinforced composite whose microstructure is represented by two general microcells accounting for different deformation mechanisms, microstrucural phases and geometry arrangement. Specifically, in this approach the microstrain modes used for building the reduced order model (ROM) are obtained through standard proper orthogonal decomposition (POD) techniques applied over snapshots of a representative sampling strain space. Additionally, a reduced number of integration points is obtained by exactly integrating the main free energy modes resulting from the sampling energy snapshots. The outcome consists of a number of dominant strain modes integrated over a remarkably reduced number of integration points which provide the support to evaluate the constitutive behavior of the microstructural phases. It is emphasized that stresses are computed according to the selected constitutive law at the reduced integration points and, therefore, the strategy inherits advantageous properties such as model completeness and customization of material properties. Overall results are discussed in terms of the consistency of the multiscale analysis, customization of the microscopic material parameters and speedup ratios compared to high-fidelity finite element (HF) simulations.

]]> María Jesús Samper https://www.scipedia.com/public/Tian_et_al_2021a Wed, 23 Jun 2021 11:28:15 +0200 https://www.scipedia.com/public/Tian_et_al_2021a <![CDATA[Shear capacity behavior of Reinforced Concrete (RC) beams strengthened with CFRP strips]]> '''Recently, reinforced concrete beams strengthened with carbon fiber reinforced polymers (CFRP) have been widespread. The objective of this research is to calculate the shear strength capacity increment of reinforced concrete beams strengthened by CFRP strips. The ABAQUS software was used to construct a model of the finite elements for beam simulation. Six beams were generated in ABAQUS software, two were control beams and the remaining four were reinforced by varying CFRP strips. All beams had the same rectangular cross-section geometry and length. The obtain results showed that CFRP can significantly increase the shear capacity of the beam. And the highest load and deflection is a little affected by the CFRP strips orientation. This study can proposes a more economical way for existing structures to improve the carrying capacity.

]]> Qian Sun https://www.scipedia.com/public/Vieira_et_al_2021a Wed, 23 Jun 2021 08:16:55 +0200 https://www.scipedia.com/public/Vieira_et_al_2021a <![CDATA[The Face-Centred Finite Volume Method for Incompressible Flows]]> Scipedia content https://www.scipedia.com/public/Alfaro-Isac_et_al_2021a Mon, 21 Jun 2021 19:39:56 +0200 https://www.scipedia.com/public/Alfaro-Isac_et_al_2021a <![CDATA[Tensor-Decomposition-Based Sequential Design of Experiments for Computer Simulations]]> A novel sequential sampling algorithm is described and tested using tensor decomposition as surrogate model through the definition of an objetive function that balances exploitation and exploration criteria.

]]> Scipedia content https://www.scipedia.com/public/Tessaro_et_al_2021a Mon, 21 Jun 2021 19:13:51 +0200 https://www.scipedia.com/public/Tessaro_et_al_2021a <![CDATA[A Geometrically Exact Shell Theory with Initial Curvatures and 3D Constitutive Models]]> Scipedia content https://www.scipedia.com/public/Vohralik_et_al_2021a Mon, 21 Jun 2021 19:12:46 +0200 https://www.scipedia.com/public/Vohralik_et_al_2021a <![CDATA[Goal-Oriented a Posteriori Error Estimation for Conforming and Nonconforming Approximations with Inexact Solvers]]> Scipedia content https://www.scipedia.com/public/Johansson_2021a Mon, 21 Jun 2021 19:12:29 +0200 https://www.scipedia.com/public/Johansson_2021a <![CDATA[Application-specific Inverse Identification for Soft Tissue Biomechanics]]> This contribution discuss the coupling between parameter identification and subsequent simulation (where the parameters are used) in the context of soft tissue biomechanics simulations. Duality-based method is used to consider the error in the identified material parameter along the usual finite element discretization error in simulations.

]]> Scipedia content https://www.scipedia.com/public/Draft_Content_348436943 Mon, 21 Jun 2021 19:12:18 +0200 https://www.scipedia.com/public/Draft_Content_348436943 <![CDATA[H-adaptive Mesh Refinement for Topology Optimization in the Framework of the Cartesian Grid finite Element Method - cgFEM]]> The growing interest in Topological Optimization (TO) in recent years is undeniable. In particular, this paper focuses on the Solid Isotropic Material Penalization (SIMP) method, broadly used because of its simple formulation and efficiency, and how h-adaptive mesh refinement in the context of the Cartesian grid finite element method, cgFEM, can improve its performance. This paper will present a combination of three methodologies based on mesh h-adaptation in cgFEM (whose hierarchical mesh and data structures are especially efficient in TO) to overcome two disadvantages of the SIMP method related to the lack of sharpness in the definition of the boundary and the influence of the finite element (FE) discretization on the final solution: 1) Use of two mesh levels: i) a mesh for the FE analysis and ii) a refined mesh, not only for integration and calculation of sensitivities but also to enhance sharpness of the boundary representation at a marginal computational cost. 2) Use a density-based refinement: a sharper boundary definition will be obtained using a basic technique where elements with intermediate density values are refined. 3) Use of solution-based refinement: the numerical solution obtained by the use of a h-adaptive analysis technique based on a recovery-type error estimator guaranties that an accurate evaluation of stress values is considered in stress-constrained TO.

]]> Scipedia content https://www.scipedia.com/public/Runesson_2021a Mon, 21 Jun 2021 19:11:56 +0200 https://www.scipedia.com/public/Runesson_2021a <![CDATA[Efficient Computation of Viscoplasticity Based on Numerical Model Reduction with Error Control]]> Scipedia content https://www.scipedia.com/public/Ekre_et_al_2021a Mon, 21 Jun 2021 19:11:35 +0200 https://www.scipedia.com/public/Ekre_et_al_2021a <![CDATA[Numerical Model Reduction with Error Estimation for Computational Homogenization of Nonlinear Poroelasticity]]> Scipedia content https://www.scipedia.com/public/Giraldo_et_al_2021a Mon, 21 Jun 2021 19:11:18 +0200 https://www.scipedia.com/public/Giraldo_et_al_2021a <![CDATA[An Adaptive Stabilized Finite Element Method Based on Residual Minimization for Unsteady Advection-diffusion Problems]]> We introduce a novel adaptive-stabilized finite element method for unsteady advection dominant problems. We built a discrete scheme by performing a residual minimization at every time step, to an ad-hoc modification of a discrete formulation obtained from the coupling of an implicit time-marching scheme and a DG formulation in space. As a result, we obtain a stable solution and a residual estimative at every discrete time level. This residual estimative can be employed to guide mesh refinement, implying a considerable reduction in the computational effort required for implicit schemes.

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