Session Details

Application of X-ray computed tomography on fracture behaviour study of cement paste at micro-scale
Hongzhi Zhang (Delft University of Technology), Branko Šavija (Delft University of Technology), Erik Schlangen (Delft University of Technology)

Micro Abstract:
3D microstructure with a cubic dimension of 100 $\mu \mathrm{m}^3$ was generated by X-ray computed tomography. Its mechanical properties were predicted by the microstructure informed lattice model. Considering the heterogeneous nature of this material, 30 specimens were investigated. Correlation analysis was conducted between the simulated mechanical properties and porosity.

A scaled boundary NURBS approach for nonlinear solid analysis
Markus Klassen (RWTH Aachen University), Margarita Chasapi (RWTH Aachen University), Bernd Simeon (University of Kaiserslautern), Sven Klinkel (RWTH Aachen University)

Micro Abstract:
In this contribution, the scaled boundary formulation is proposed as a discretization technique which is based on the isogeometric concept. By this means, the representation of a solid body is given by the boundary surface of the body and a radial scaling parameter which is used to describe the interior. NURBS shape functions are employed to define the geometry as well as to approximate the solution field. The numerical examples are given for elasto-plastic material behavior at small strains.

The Particle Finite Element Method in Solid Mechanics Applications
Markus Manuel Schewe (TU Dortmund University), Andreas Menzel (TU Dortmund University)

Micro Abstract:
In manufacturing processes, the separation of material occurs either on purpose or as undesired wear of tools and work-pieces. The PFEM offers a framework to deal with configurational changes through repeated remeshing and shape detection of a point-cloud, representing the body. A standard Finite-Element-Analysis can be performed with suitable transformations of variables between meshes. The method is presented along with representative results in the field of solid mechanics.

Two-scale Reduced Basis Homogenization under Large Deformations
Oliver Kunc (University of Stuttgart), Felix Fritzen (University of Stuttgart)

Micro Abstract:
In this work, the first aim is to solve the task of two-scale homogenization of nonlinear materials for large deformations. We propose a model with a reduced basis for the deformation gradient. The accuracy of the predictions is evaluated online. The main benefit of this approach is the reduction of both CPU time and memory requirements. It also opens opportunities for generalization and further acceleration which are also discussed, e.g. data-driven techniques.

Computation of multiphysics processes in deformable media
Bilen Emek Abali (Technische Universität Berlin)

Micro Abstract:
Micro electro-mechanical systems (MEMS) exploit the coupling between mechanics and electromagnetism. For an accurate simulation of this coupling we need a strategy to calculate deformation, temperature, and electromagnetic fields in solids, at once. By using open-source packages, we present an approach to simulate MEMS by solving nonlinear and coupled equations at once by using finite difference method in time and finite element method in space.

Regenerating CAD Models with OpenCASCADE and pythonOCC from Numerical Models with Application to Shape Optimization
Altug Emiroglu (Technical University of Munich), Andreas Apostolatos (Technical University of Munich), Roland Wüchner (Technical University of Munich), Kai-Uwe Bletzinger (Technical University of Munich)

Micro Abstract:
Sensitivity filtering methods are unavoidable when numerical shape optimization is considered. A mortar based sensitivity filtering method which incorporates underlying CAD parametrization of the numerical models is proposed. The method is combined with a software environment which utilizes the capabilities of the opensource library OpenCASCADE and pythonOCC module respectively for the regeneration of the CAD models directly from the optimized numerical models as a result of the procedure.

The Heterogeneous Multiscale Finite Element Method (FE-HMM) for nonlinear problems in solid mechanics
Andreas Fischer (University of Siegen), Ajinkya Gote (University of Siegen), Bernhard Eidel (University of Siegen)

Micro Abstract:
The present work proposes a nonlinear extension of the FE-HMM for the homogenization of microheterogeneous solids. The advantage of FE-HMM compared with FE$^2$ is the existence of a priori convergence estimates, which allow for optimal strategies in mesh refinements. While these estimates were proved for linear problems so far, we assess their validity for geometrical nonlinearity and hyperelastic constitutive laws. Applications to complex microstructures showcase the performance of the method.

Discussion of crack initiation in metal matrix composites
Markus Sudmanns (Karlsruhe Institute of Technology (KIT)), Katrin Schulz (Karlsruhe Institute of Technology (KIT))

Micro Abstract:
Understanding the mechanisms of micro-crack initiation in metals is of high academic as well as industrial interest. In this contribution, we discuss the role of stress concentrations in metal matrix composite materials as the cause of crack initiation. Using a continuum representation of dislocation microstructures, we compare microscale simulations to experimental studies of crack initiation and discuss the dislocation microstructure around a crack tip.

Virtual tests based on model reduction strategies for fatigue analysis
Mainak Bhattacharyya (Leibniz Universität Hannover), Amelie Fau (Leibniz Universität Hannover), Udo Nackenhorst (Leibniz Universität Hannover), David Néron (Ecole Normale Supérieure Paris-Saclay, Université Paris-Saclay), Pierre Ladevèze (Ecole Normale Supérieure Paris-Saclay, Université Paris-Saclay)

Micro Abstract:
Virtual tests for fatigue considering a large number of cycles in perspective of continuum damage mechanics are generally avoided due to numerical expense. To tackle this problem, a Proper Generalised Decomposition model reduction technique in time and space, and a multi-time scale approach are proposed. These innovations used in a non-incremental LATIN framework, reduce the computational cost drastically and can be contemplated to perform virtual analysis of high-cycle fatigue tests.

Parallel Stabilized FEM for the Flow Simulations of Microstructured Fluids
Metin Cakircali (Forschungszentrum Jülich GmbH), Marek Behr (RWTH Aachen University)

Micro Abstract:
The Single-Walled Carbon Nanotubes (SWNT) have unique properties that make them ideal for nano-materials. We use efficient numerical methods to improve our understanding of the macroscale assembly processes (e.g., fiber spinning). The Galerkin/Least-Squares formulation is derived for the fully coupled transient equation systems. Space-time elements with equal order velocity-pressure-order parameter are used for several relevant test cases. The results are compared with available literature data.

Comparative study of finite-element-based fatigue analysis concepts for adhesive joints in wind turbine rotor blades
Pablo Noever Castelos (Leibniz Universität Hannover), Michael Wentingmann (Leibniz Universität Hannover), Claudio Balzani (Leibniz Universität Hannover)

Micro Abstract:
This contribution aims to clarify the need for considering non-proportionality in the fatigue analysis of adhesive joints of wind turbine rotor blades. The comparison covers three different blade configurations (Length: 20 m, 40 m and 80 m) in order to derive generalized conclusions by extracting a correlation between non-proportionality, radial position and blade size. The results further indicate which type of fatigue analysis has to be performed for reliable life estimations.

Data-driven crack assessment
Katrin Schulz (Karlsruhe Institute of Technology (KIT)), Valentin Verrier (Karlsruhe Institute of Technology (KIT)), Stephan Kreis (Karlsruhe Institute of Technology (KIT))

Micro Abstract:
Different methods of selection and feature creation are considered in order to discuss the chances and limits of a data driven assessment of cracks. We apply different methods of data mining to find correlations which yield an unconventional approach for the prediction of critical crack states and material failure. The results of different explorative multivariate analyses will be compared and discussed in the context of applicability in engineering science.

Flexible Wheelset Models in Dynamic Interaction with Track
Mustapha Afriad (Sorbonne Universités, Université de technologie de Compiègne), Mohamed Rachik (Sorbonne Universités, Université de technologie de Compiègne), Ludovic Cauvin (Sorbonne Universités, Université de technologie de Compiègne), Olivier Cazier (French National Railways Company (SNCF)), Guy-Leon Kaza (Sorbonne Universités, Université de technologie de Compiègne)

Micro Abstract:
Until now, multibody models of vehicle-track interaction consider rigid components. In order to improve these models, it seems necessary to consider flexible components by coupling finite element analysis with multibody dynamics simulations. The main objective of this study is to present the methodology used to integrate wheelset flexibility in a multibody model of train. Wheel-rail contact forces and vehicle stability obtained with rigid wheelset and flexible wheelset will be compared.

Determination of optimal damping for passive control of vibration based on the design of limit cycles
Rafael A. Rojas (Free University of Bozen-Bolzano), Erich Wehrle (Free University of Bozen-Bolzano), Renato Vidoni (Free University of Bozen-Bolzano)

Micro Abstract:
The optimal design of passive vibration control is a challenge for both application and research. These design methods are based on structure optimization and models are typically solved in frequency domain. This work explores the benefits of introducing state-space methods on passive control. We propose an optimization approach based on the design of the limit cycles of mechanical systems under periodic forces. The method is applied to an example of damping optimization.

A Variational Level Set Approach to Ferroelectrics
Robin Schulte (TU Dortmund University), Andreas Menzel (TU Dortmund University), Bob Svendsen (RWTH Aachen University)

Micro Abstract:
The level set formulation, in contrast to a laminate approach, provides more information considering domain wall kinetics in ferroelectrics since the microstructure is simulated with a spatial resolution. The level set function is defined as a signed distance function to the domain wall. In the variational approach, an internal energy penalises the deviation from the signed distance function due to numerical errors which is computationally more efficient than the commonly used reinitialization.

Virtual simulation of deformation behavior of NiTi stents used in minimally invasive surgery
Sharath Chandra Chavalla (Otto von Guericke University Magdeburg), Daniel Juhre (Otto von Guericke University Magdeburg)

Micro Abstract:
Finite element method is a popular computation tool which has its own drawbacks. In recent years, a numerical method called isogeometric analysis (IGA) has been developed which bridges gap between CAD and FEM. Unlike FEM, IGA uses high-order and high-regular basis functions (nonuniform rational B-splines-NURBS). The aim of this project is efficient simulation of the deformation behavior of carotid NiTi stents using IGA which makes a step closer in realising realtime simulation of stents.

Parameter identification for thermo-mechanically coupled material models
Lars Rose (TU Dortmund University), Andreas Menzel (TU Dortmund University)

Micro Abstract:
For material models which are based on a phenomenological set of material parameters, the identification of such a set for a certain material model and a related material is the foundation of predictive simulations. The current work focuses on the performance of a parameter identification including the algorithmic structure, as well as the realisation of suitable experiments under inhomogeneous states of deformation and the influence of weighting parameters within the objective function.

A method for the elimination of shear locking effects in an isogeometric Reissner-Mindlin shell formulation
Georgia Kikis (RWTH Aachen University), Wolfgang Dornisch (University of Kaiserslautern), Sven Klinkel (RWTH Aachen University)

Micro Abstract:
Shell elements for slender structures based on a Reissner-Mindlin approach struggle in pure bending problems. The stiffness of such structures is overestimated due to the transversal shear locking effect. Here, an isogeometric Reissner-Mindlin shell element is presented, which uses adjusted control meshes for the displacements and rotations in order to create a conforming interpolation of the pure bending compatibility requirement. The method is tested for standard numerical examples.