Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference最新文献

{"title":"Modelling delamination of a DCB test by using non-linear truss interface elements and plate elements with assumed shear strain","authors":"Ivan Hlača, Dragan Ribarić, Leo Škec, Maedeh Ranjbar Zefreh","doi":"10.4995/yic2021.2021.12587","DOIUrl":"https://doi.org/10.4995/yic2021.2021.12587","url":null,"abstract":"Fracture resistance of structural adhesive joints is key for their application in the industry. Mode-I adhesive joint delamination is the most severe type of fracture and the possibility of this outcome should be avoided whenever possible. In this work we are investigating mode-I delamination of plate-like specimens, where the width is comparable to the length. In such cases anticlastic bending of the plates takes place on the debonded part and the crack front is a curve rather than a straight line. We model the interface by means of discrete non-linear truss elements with embedded exponential traction-separation law [1]. Such choice is justified because in this test, only pure mode-I (opening) displacements occur at the interface, which in our case will cause axial elongation of the truss elements. The plates are modelled using 4-node plate finite elements derived by the assumed shear strain approach that pass the general constant-bending patch test [2]. Cohesive-zone interface parameter identification is performed by a direct method (J-integral) [3] and by virtual experiments regression. Numerical tests have been performed and the exponential cohesive-zone interface model compared against the bi-linear in terms of precision, robustness and computing time. The results confirm the experimentally observed behaviour with anticlastic bending of the arms and the curved crack front.","PeriodicalId":406819,"journal":{"name":"Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126323907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and modelling of bioinspired 3D printed structures","authors":"C. L. Garrido, E. Alabort, D. Barba","doi":"10.4995/yic2021.2021.12529","DOIUrl":"https://doi.org/10.4995/yic2021.2021.12529","url":null,"abstract":"3D printed metamaterials are a human-designed class of material capable of providing uncommon properties unseen in nature. However the freedom power of design provided by additive manufacturing in metamaterials is useless if reliable and efficient modelling design tools are not available. The objective of this work is to evaluate, validate and study the different options for finite element simulation of bio-inspired metamaterials to provide the best solutions in terms of material properties accuracy and computational efficiency. Based on this study we have developed a new hybrid material agnostic modelling method to compute the mechanical response of beam based bioinspired metamaterials with similar precision of 3D explicit meshed models. Different variables in the latticed models were investigated, these included different element sizes and element types (volumetric and beam elements). The effects of these variables on the elastic modulus and yield strength of a lattice structure were addressed. The geometrical models were printed in Ti6Al4V using selective laser melting technique and experimentally tested for the validation of the computational results. On the basis of the volumetric results, multi-material beam models were constructed and evaluated providing with accurate results in low computational times and recreating the plastic failure phenomena observed experimentally.","PeriodicalId":406819,"journal":{"name":"Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121605729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the calculation of the Kalker's creep coefficients for non-elliptical contact areas","authors":"J. Gómez-Bosch, J. Giner-Navarro, J. Carballeira","doi":"10.4995/yic2021.2021.12313","DOIUrl":"https://doi.org/10.4995/yic2021.2021.12313","url":null,"abstract":"In order to properly analyse new challenges in railway dynamics, such as corrugation or rolling noise, it is necessary to obtain an accurate solution of the tangential contact problem. Traditionally, in most railway dynamic softwares, tangential contact has been calculated based on the FASTSIM algorithm. This method provides a fairly accurate solution with reduced computational cost. However, when non-Hertzian contact conditions have to be assumed, its calculations are no longer accurate, which makes FASTSIM not useful for this purpose. Also, there exist tangential contact models which are able to obtain an accurate solution for non-Hertzian conditions, but their computational cost makes them inappropriate for dynamic calculations. Therefore, this proposed new method is developed in order to satisfy the need of a model able to obtain results under non-Hertzian conditions, without an excessive computational cost.In the present work, a new extension of the FASTSIM method for the calculation of non-elliptical contact areas is proposed. The main complexity of this method lies on the calculation of the adhesion coefficients. Originally, these coefficients are obtained from Kalker’s Linear Theory, which gives exact results for elliptical contact areas, but its accuracy lowers under non-Hertzian conditions. To obtain them, a stationary contact model which assumes infinite friction coefficient is developed. This model is obtained from the kinematics of the different configurations of the wheel and the rail, and from the constitutive relations corresponding to an infinite half-space. This model is solved numerically by a collocation method (imposing the solution over the contact area). By comparison with the results obtained with reference models, the accuracy and computational cost of the proposed model is analysed. These comparisons show that the proposed model is 50 times faster than the reference model, and the errors are under 3% in most of the carried-out analysis.   ","PeriodicalId":406819,"journal":{"name":"Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128141066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical investigation on a block preconditioning strategy to improve the computational efficiency of DFN models","authors":"L. Gazzola, M. Ferronato, S. Berrone, S. Pieraccini, S. Scialò","doi":"10.4995/yic2021.2021.12234","DOIUrl":"https://doi.org/10.4995/yic2021.2021.12234","url":null,"abstract":"Simulation of fluid flow dynamics in fractured porous media is an important issue in several subsurface models. The intricate network generated by hundreds of fractures produces complex multi-scale geometries that can be modelled in different ways. In contrast to homogenization-based techniques, discrete fracture network (DFN) models explicitly represent the fracture planes and their properties, prescribing continuity constraints for the fluid flow along the linear intersections. We focus on the formulation of the DFN model as a PDE-constrained optimization problem as originally proposed in [1].  This approach uses a non-conforming mesh and decouples the global problem in local ones, thus being suitable for an effective parallel implementation [2]. Imposing the flow continuity by a Lagrange-multiplier technique gives rise to a linearized algebraic problem where the global matrix K has a symmetric saddle-point structure with a rank-deficient leading block. In this work, we focus on accelerating the iterative solution of the system with matrix K by introducing effective block preconditioning techniques. First, an appropriate permutation of K is performed, in order to avoid a singular leading block though losing the global symmetry. Then, we restrict K to the coarse space of the fracture traces and solve inexactly the projected matrix by either an explicit or a matrix-free approach. The granular properties and the structure of K blocks are properly exploited in order to guarantee an efficient parallel implementation. The proposed algorithm is tested in applications of increasing size to verify its robustness and effectiveness in the acceleration of the iterative linear solver.[1]      S. Berrone, S. Pieraccini, S. Scialò. A PDE-constrained optimization formulation for Discrete Fracture Network flows, SIAM J. Sci. Comput., Vol. 35, pp. B487-B510, (2013) [2]      S. Berrone, S. Scialò, F. Vicini. Parallel meshing, discretization and computation of flow in massive Discrete Fracture Networks, SIAM J. Sci. Comput., Vol. 41, pp. C317-C338, (2019) ","PeriodicalId":406819,"journal":{"name":"Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130913008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A vibroacoustic model of the stationary railway wheel for sound radiation prediction through an axisymmetric approach","authors":"Víctor Tomás Andrés Ruiz, José Martínez Casas, Javier Carballeira Morado, Francisco David Denia Guzmán","doi":"10.4995/yic2021.2021.12584","DOIUrl":"https://doi.org/10.4995/yic2021.2021.12584","url":null,"abstract":"In previous works [1,2], different dynamic models of the railway wheel have been developed to predict its sound radiation; however, there are still certain aspects that can be improved. Specifically, the high computational cost of these models, either because they solve the fluid-structure interaction problem or because they solve the dynamics and acoustics of the three-dimensional wheel, make it difficult to carry out optimization simulations (involving a large number of computations) with the aim of achieving quieter designs. In the present work, a vibroacoustic model of the wheel is developed using an axisymmetric approach, yielding an efficient and comprehensive acoustic prediction tool. The calculation methodology consists of, firstly, adopting an axisymmetric approach to solve the vibrational dynamics of the wheel from its cross section, using finite element techniques [3]; subsequently, the acoustic radiation of the three-dimensional wheel is calculated from the dynamics of the cross section through an analytical formulation based on the harmonic nature of the response along the circumferential direction. Additionally, the wheel rotation is introduced in the model using an Eulerian approach [4], in order to consider the associated gyroscopic and inertial effects. Finally, the vibroacoustic model developed in the current work is benchmarked against commercial software that solves the fluid-structure interaction problem, showing an improvement in the computational performance.","PeriodicalId":406819,"journal":{"name":"Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123843192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Model-order reduction for nonlinear dynamics including nonlinearities induced by damage","authors":"A. Daby-Seesaram, A. Fau, P. Charbonnel, D. Néron","doi":"10.4995/yic2021.2021.13255","DOIUrl":"https://doi.org/10.4995/yic2021.2021.13255","url":null,"abstract":"Fragility curves are one of the main tools used to characterize the resistance to seismic hazard ofcivil engineering structures, such as nuclear facilities. These curves describe the probability thatthe response of a structure exceeds a given criterion, called failure criterion, as a function of theexpected seismic loading level. The numerical construction of these curves leads to many queriesto CPU intensive nonlinear computations. Indeed, a large number of loading scenarios must betreated, but also the uncertainties inherent to the structure must be taken into account through areliability study.The objective of this work is to implement a strategy based on model-order reduction for a calcu-lation generally enabling very important computational time savings. Among the diffeerent possible approaches, the Proper Generalized Decomposition (PGD) coupled with the LATIN method [1] is particularly well suited for solving parametrized problems in nonlinear mechanics in order to buildnumerical charts [2]. The LATIN-PGD method is an iterative approach that seeks the solution of a given problem by building in a greedy way a dedicated reduced-order basis. This basis can bereused and enriched to solve parametrized problems, allowing a very good numerical effciency. It has been applied to solve a wide range of problems in mechanics and more recently for earthquake-engineering applications [3] and provides a particularly good framework for the computation ofnumerical charts.In this contribution, a strategy will be proposed to evaluate the damage state of piping components,characteristic of the primary circuits of pressurized water reactors, subjected to seismic loading consecutive to a preliminary design thermal loading. The developed methodology, using a damageableelasto-plastic material, integrates the initial state of damage prior to the seismic event, which isone of the uncertain parameters of the problem.REFERENCES[1] P. Ladevèze. Nonlinear computational structural mechanics: new approaches and non-incremental methods of calculation. Mechanical engineering series. Springer, New York, 1999.[2] D. Néron, P.-A. Boucard, and N. Relun. Timespace PGD for the rapid solution of 3d nonlinearparametrized problems in the manyquery context. International Journal for Numerical Methodsin Engineering, 103(4):275{292, 2015.[3] S. Rodriguez, D. Néron, P.-E. Charbonnel, P. Ladevéze, and G. Nahas. Non incremental LATIN-PGD solver for nonlinear vibratoric dynamics problems. In 14ème Colloque National en Calculdes Structures, CSMA 2019, Presqu'^Ile de Giens, France, May 2019.","PeriodicalId":406819,"journal":{"name":"Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127112684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multilevel matrix-free preconditioner to solve linear systems associated with a the time-dependent SPN equations","authors":"A. Carreño, A. Vidal-Ferràndiz, D. Ginestar, G. Verdú","doi":"10.4995/yic2021.2021.12510","DOIUrl":"https://doi.org/10.4995/yic2021.2021.12510","url":null,"abstract":"Inside a nuclear reactor core, the neutronic power distribution can be approximated by means of the multigroup time-dependent  simplified spherical harmonics equations. In particular, this work uses a formulation where the time derivatives of the even spherical harmonics moments are assumed equal to zero. This treatment yields to diffusive equations of order two that only depend on the position and time.For the spatial discretization of the equations, a continuous Galerkin high order finite element method is applied. In the time discretization, two sets of equations appear: one related to the neutron moments and the other related to the delayed neutron precursor concentrations. Moreover, these time differential equations are usually stiff. Thus, a semi-implicit time scheme must be proposed that needs to solve several linear systems in each time-step. And generally, these systems must be preconditioned.The main aim of this work is to speed up the convergence of the linear systems solver with a multilevel preconditioner that uses different levels of energy, spherical moments and degrees in the finite element method. Furthermore, the matrices that appear in this type of system are large and sparse. A matrix-free implementation is used to avoid the full assembly of the matrices. Therefore, the multilevel preconditioner must be applied by matrix-vector products.Different benchmark transients test these techniques. Numerical results show, in the comparison with classical methodologies, an improvement in terms of memory requested and time needed to obtain the solution.","PeriodicalId":406819,"journal":{"name":"Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116756452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shape Optimization for Thermal Insulation Problems","authors":"S. Tozza, G. Toraldo","doi":"10.4995/yic2021.2021.12288","DOIUrl":"https://doi.org/10.4995/yic2021.2021.12288","url":null,"abstract":"Thermal insulation represents one of the major challenges for energy efficiency. Problems related to insulation are well-known and widely studied in mathematical physics. Neverthless, mathematics involved is still very tricky especially when one looks at shape optimization issues [1, 2], and sometimes the answers are not so intuitive [3].In this talk we will consider two domains: an internal (fixed) ball of radius r and an external domain whose geometry varies. Physically, we are considering a domain of given temperature, thermally insulated by surrounding it with a constant thickness of thermal insulator. Our question is related to the best (or worst) shape for the external domain, in terms of heat dispersion (of course, under prescribed geometrical constraints).  Mathematically, our problem is composed by an elliptic PDE with Robin-Dirichlet boundary conditions. This work is still in progress and we want to share someremarks and open questions, in addition to the results obtained so far.REFERENCES[1] F. Della Pietra, C. Nitsch, C. Trombetti, An optimal insulation problem. Math. Ann., (2020). https://doi.org/10.1007/s00208-020-02058-6[2] D. Bucur, G. Buttazzo, C. Nitsch, Two optimization problems in thermal insulation. Notices Am. Math. Soc., 64(8): 830--835, 2017.[3] D. Bucur, G. Buttazzo, C. Nitsch, Symmetry breaking for a problem in optimal insulation. J.Math. Pures et Appl., 107(4): 451--463, 2017.","PeriodicalId":406819,"journal":{"name":"Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116220826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effect of a consistent linearization on the numerical stability of hydrid-elements for quasi-incompressible hyperelastic solids","authors":"P. Schneider, Josef Arthur Schönherr, C. Mittelstedt","doi":"10.4995/yic2021.2021.12174","DOIUrl":"https://doi.org/10.4995/yic2021.2021.12174","url":null,"abstract":"The numerical ill-posedness of irreducible (purely displacement-based) finite element formulations for quasi-incompressible materials requires the usage of mixed formulations extended by additional primary unknowns instead. In the talk, we revisit the well-known three-field formulation introduced by Simo and Taylor, [1]. However, while in [1] a semi-discretization is used to eliminate the additional primary unknowns before the problem is linearized in terms of the not yet discretized displacement field, we introduce a consistent linearization of the three-field formulation on the continuum-level. In the latter case,  static condensation is used to eliminate the additional unknowns on the element-level after the linearization of the continuum formulation in order to derive discontinious hybrid-elements.A family of Simo-Taylor-Pister (STP) elements, as well as a family of elements based on the continuum-level linearization (CL3F), designed to coincide in terms of the  interpolation scheme, the number of assembled degrees of freedom and the number of integration points with the Abaqus hybrid-elements (C3D8H,C3D20H,C3D10H) are compared to those elements by benchmark tests. Material parameters were obtained by least-square fitting to experimental data of an industrial NR/IR-blend (natural rubber / isoprene rubber) used for damping applications.All elements are locking-free. The STP-elements show the known severe stability issues. In general the maximum stable step-width of the Abaqus hybrid-elements is way higher in comparison to the STP-elements. However, the CL3F-elements outperform the Abaqus elements in general without the usage of numerical stabilization. Especially in combination with nonlinear compression models the advantage of the CL3F is huge - here the stable step-width is up to 22-times larger. Details can be found in [2].","PeriodicalId":406819,"journal":{"name":"Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124390492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Explicit expressions for elastic constants of osteoporotic lamellar tissue and damage assessment using Hashin failure criterion","authors":"Raquel Megías Díaz, Ricardo Belda González, Ana Vercher Martínez, Eugenio Giner Maravilla","doi":"10.4995/yic2021.2021.12442","DOIUrl":"https://doi.org/10.4995/yic2021.2021.12442","url":null,"abstract":"Osteoporosis is one of the most prevalent diseases in the last decades. The ageing of the population has led to a large increase in the number of people who suffer this musculoskeletal disease. For this reason, an early diagnosis of osteoporosis in order to improve bone fracture risk assessment is essential. To this end, efforts to enhance the knowledge in the elastic, post-yielding and fracture properties of bone are required.In this work, we have derived explicit equations to estimate the orthotropic elastic constants of lamellar tissue as a function of the porosity at tissue level (microporosity) and the bone mineral density, following the multiscale approach presented in [1]. Microporosity has been explicitly mod-elled in a range from 1% to 25% [2]. Two types of pores, ellipsoid and sphere-shaped, have been modelled. On the other side, we have obtained the elastic constants of lamellar tissue in a range of bone mineral density comprised from 0,653 g/cm3 to 1,50 g/cm3 [3]. A non-linear multivariable regression by means of the least square fitting has been performed and the explicit expressions for the elastic constants of lamellar tissue have been provided as a function of the volumetric bone mineral density and porosity.Moreover, independent quasi-static load cases are numerically simulated. Bone failure onset has been modeled by Hashin’s orthotropic failure criterion and damage evolution has been assessed through the material property degradation (MPD) method. Strength limits of lamellar tissue have been inferred from Ascenzi and Bonucci [4] and Giner et al. [5]. Results reveal that failure onset is mainly due to the tension in the transversal direction of the mineralized collagen bundles.","PeriodicalId":406819,"journal":{"name":"Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115836060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}