bluuebunny/crossref_metadata_2025_split huggingface dataset:
A polyconvex phase‐field approach to fracture with application to finite‐deformation contact problems
Authors: Franke Marlon , Dittmann Maik , Hesch Christian , Betsch Peter 
Published: March 2018

AbstractVariationally consistent phase‐field methods allow for an efficient investigation of complex three‐dimensional fracture problems (see [1, 2]). However, formulations for large deformation problems often exhibit a lack of numerical stability for different loading scenarios. In the underlying contribution a novel formulation for finite strain polyconvex elasticity is adapted to phase‐field fracture problems. In particular we introduce a new anisotropic split based on the principal invariants of the right Cauchy‐Green strain tensor for a proper treatment of fracture within the polyconvex framework (see [4]). This polyconvex phase‐field fracture formulation can be implemented in a straightforward manner and improves the numerical stability. Furthermore, a fourth order crack density functional is considered to improve accuracy and convergence. To account for the C1 requirement the system is embedded in a sophisticated isogeometric framework with the ability of local refinement. Eventually, a variationally consistent Mortar contact algorithm is applied (see [3]) to handle contact boundaries. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Automatic quadtree‐based modeling using a coupled SBFEM/SCM approach
Authors: Gravenkamp Hauke , Duczek Sascha , Birk Carolin 
Published: March 2018

AbstractWe present an approach for the automatic image‐based modeling in computational mechanics. The geometry is divided into subdomains by employing a quadtree‐decomposition. The scaled boundary finite element method (SBFEM) can directly be applied to quadtree meshes without introducing hanging nodes, while the spectral cell method (SCM) allows for an accurate representation of curved boundaries. Hence, a combination of both methods can lead to highly accurate and reliable results in a fully automatic simulation environment. The performance of this coupled SBFEM/SCM approach is demonstrated by means of a modal analysis of a violin soundboard. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of strain‐rate effects in Al foams and Ni/Al hybrid foams on different scales
Authors: Jung Anne , Luksch Jutta , Felten Markus , Reis Martin , Sory David R. , Pullen Andy D. , Proud William G. , Larcher Martin , Valsamos Georgios , Solomos George 
Published: March 2018

AbstractOpen‐cell metal foams are a new class of cellular materials with structural features resembling those of lightweight load‐bearing materials such as cancellous bones and wood. Their high stiffness‐to‐weight ratio coupled with their typical long, flat stress‐strain response make them ideal candidates as cost‐effective shock energy absorbers in crashworthiness, impact loading and blast mitigation strategies. The macroscopic mechanical properties of foams are strongly influenced by both the mechanical behaviour of single pores at the mesoscopic level and the struts and their structure at the microscopic length‐scale, based on a strong structure‐property relationship. This is shown in the present contribution where an experimental‐numerical investigation has been conducted demonstrating the existence of strain‐rate effects at different hierarchical scales. Micro inertia effects arising due to the pore geometry as well as further strain‐rate effects stemming from the rate‐sensitivity of the Ni coating in Ni/Al hybrid foams are also outlined. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of Multipreconditioned Iterative Algorithms in Dual Domain Decomposition Methods for Structural Dynamics
Authors: Leistner Michael , Rixen Daniel , Gosselet Pierre 
Published: March 2018

AbstractWe apply a multipreconditioned domain decomposition method based on Finite Element Tearing and Interconnecting to linear structural dynamics with highly heterogeneous material properties. A recently published method to build and select the multiple directions is presented and applied. We hint at possible problems when localized phenomena are considered and present a new simple measure that extends the selection process in existing algorithms. We show numerical results and conclude how to effectively prevent a possible degeneration of the minimization space basis. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigations on a FEM‐sub‐model for “Die‐Less‐Hydroforming” weld seams
Authors: Metzger Andreas , Ruff Daniel C. , Ummenhofer Thomas 
Published: March 2018

AbstractA global forming model for the special and unconventional forming process called “Die‐Less‐Hydroforming” that can be used for the inflation of arbitrary double‐layered or multi‐layered seal‐welded blanks was already presented by the authors in recent publications. While looking on the modeling of the specific seal‐weld in this global model, as a special modeling step the elements at the edges of the blanks are folded towards each other and after that the seal‐weld is modeled by merging the resulting duplicated nodes in the welded joining zone. This paper focuses on the investigation whether this modeling strategy for the seal‐weld is appropriate, i.e. whether the load‐displacement‐performance and stiffness behavior correspond to reality. This was investigated with a FEM‐sub‐model within LS‐DYNA in combination with a specially developed experimental benchmark‐test for the investigation of “Die‐Less‐Hydroforming” weld seams. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local buckling of laminated composite beams based on different plate theories
Authors: Herrmann Johannes , Kühn Torsten , Müllenstedt Tjorven , Mittelstedt Siham , Mittelstedt Christian 
Published: March 2018

AbstractThis paper presents an approximate approach for the local buckling analysis of prismatic composite laminated beams under uniaxial compression wherein the segments of the beams (i.e. flanges and webs) are assumed to be moderately thick so that advanced plate theories that transcend the restrictions of classical laminated plate theory (CLPT) need to be employed. We present a novel approximate analysis method based on the so‐called discrete plate approach during which the segment of interest is separated from the beam and is subjected to rotational restraints at the cutting edges. The analysis itself employs rather simple shape functions for the local buckling modes in conjunction with a Rayleigh‐type approach using the principle of minimum elastic potential of the buckled segment wherein we use the kinematic assumptions of Reddy's third‐order shear deformation theory (TSDT). The results are compared to comparative computations based on CLPT and first‐order shear deformation theory (FSDT), and a good agreement is found especially between FSDT and TSDT which lends credibility to the present approach, however neither employing the strict limitations of CLPT imposed by Kirchhoff's classical kinematic assumptions, nor requiring shear correction factors as they are generally required in the framework of FSDT and which is still a topic of on‐going research. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical investigation of a walking soft robot
Authors: de Payrebrune Kristin M. , O'Reilly Oliver M. 
Published: March 2018

AbstractInterest in soft robots is motivated by their enormous potential in applications with close contact to humans or unpredictable situations for which their soft structure and versatility is beneficial. New mathematical models and control strategies are required to optimize the geometry and performance of the soft components of these robots. The authors use a nonlinear rod model to describe a pneumatically actuated quadruped soft robot and to study the influences of different parameters on its performance. Although the model does not accommodate contact situations perfectly, it is suitable to study general interrelations. These resulting studies serve to enhance the development of soft robots. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stress solutions for joints with nonlinear adhesives
Authors: Rosendahl Philipp L. , Stein Nicolas , Becker Wilfried 
Published: March 2018

AbstractA simple predictive stress analysis model for adhesive joints with nonlinear adhesives is presented. The model allows for the treatment of various joint designs with shear‐flexible laminate or isotropic adherends. Both elastic‐plastic and hyperelastic adhesives are covered. Using a general sandwich‐type model of the adhesive bondline, the governing differential equations are derived analytically and solved numerically. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of the original and the spectral system of an elastic rotor in two‐lobe bearings with an active geometry variation
Authors: Becker Kai , Seemann Wolfgang 
Published: March 2018

AbstractThe improvement of the dynamic behaviour of an elastic rotor which is supported by journal bearings represents an ongoing field of research, whereby various modifications of the corresponding bearings and their geometry have been proposed in literature. In order to suppress or at least to decrease unwanted oscillations due to negative effects of instability phenomena of the ’oil‐whirl’‐ and/or ’oil‐whip’‐type, a two‐lobe bearing with an active geometry variation is suggested as an alternative approach. A systematic investigation of the dynamic behaviour of a Jeffcott rotor, which is supported by the mentioned bearing type, is performed by means of the associated spectral system. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of Vibrations Induced by Dry Friction in a Pin‐on‐Disk Experimental Set‐up
Authors: Kapelke Simon , Oestringer Lukas J. , Seemann Wolfgang 
Published: March 2018

AbstractHigh‐frequency vibrations have been shown to smooth the effective characteristics of dry friction and may be used in order to quench undesired phenomena such as friction induced vibrations. As the agreement between classical modelling and related experimental results appears to be insufficient, the effect of contact compliance on vibrational smoothing of dry friction has been discussed. Recently, a pin‐on‐disk experimental set‐up has been presented in order to validate the corresponding results. Within this contribution, selected properties of the experimental set‐up are analysed. Due to a negative slope in the friction‐velocity characteristics, friction induced vibrations can be observed at low sliding velocities. The oscillatory behaviour of a corresponding minimal model is investigated and compared to the experimental results. When applying appropriate high‐frequency excitation, the friction‐velocity characteristics are smoothed and, consequently, friction induced vibrations can be quenched. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Considering Nonlinearities to Design Micro System's Vibrational Sensitivity
Authors: Roeser Dennis , Gutschmidt Stefanie , Sattel Thomas 
Published: March 2018

AbstractThis contribution analyses the impact of nonlinearities on the sensitivity of micro‐electro‐mechanical sensors measuring quantities based on a change in resonance frequency. The considered sensor is an array of cantilevers which have an integrated actuator and sensor. The mathematical model presented to describe the motion of this array is based on a coupled thermoelastic equation of motion which has a forced and a parametric excitation. Finally, a concept is presented to utilize a two‐to‐one internal resonance to increase a micro system's vibrational sensitivity. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of material parameters for a sheet‐layered lamination stack
Authors: Baloglu Maximilian Volkan , Willner Kai 
Published: March 2018

AbstractThe numerical simulation of sheet‐layered lamination stacks is a challenging task in structural mechanics due to the layout of these components. Depending on the manufacturing process, these sheets are either linked together with the help of a bonding varnish or are just packed up and basically free to slip inside of the stack, which can result in a nonlinear deformation behavior. To avoid a full FE‐simulation incorporating every layer, homogenization can be applied to identify a surrogate material model to achieve the desired accuracy by gaining performance. In this paper, a transversely isotropic material model is analytically formulated for a lamination stack with isotropic sheets in contact, which is captured with the help of a linear penalty method. The resulting stress‐strain relation is compared to results obtained by a numerical homogenization. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical investigations of CMC nozzle structures: constitutive modelling and finite element technology
Authors: Barfusz Oliver , Schwarze Marco , Reese Stefanie 
Published: March 2018

AbstractThis work deals with the development of numerical tools predicting the lifetime of nozzle structures made of ceramic matrix composites (CMC). These materials are favorable for thermostructural components due to their excellent specific mechanical properties, high thermal conductivity and thermoshock resistance. The anisotropic constitutive behaviour of the CMC is reflected by a continuum model which is micro‐mechanically motivated. The model is based on structural tensors representing different fibre orientations. Furthermore, the thin structure of the nozzle requires an appropriate finite element technology in order to overcome locking phenomena. For this reason, a solid‐shell formulation with reduced integration is utilized, for which the implementation of the fibre orientation is crucial. The enhanced assumed strain (EAS) concept is used to avoid volumetric locking as well as Poisson thickness locking. The transverse shear and curvature thickness locking are cured by the assumed natural strain (ANS) concept. Using reduced integration together with hourglass stabilization leads to high computational efficiency. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermodynamically consistent modelling of recrystallization and grain coarsening in precipitation‐hardened alloys
Authors: Kertsch Lukas , Helm Dirk 
Published: March 2018

AbstractThe strength of technically relevant alloys is mainly determined by the grain size distribution, the amount and size of precipitates, solid‐solution hardening and work hardening. A reliable material model to capture these effects should be formulated within a comprehensive thermodynamic framework. The strategy of rational extended thermodynamics is applied to derive a thermodynamically consistent model representing the coupling between elastoplastic deformation, the evolution of the grain structure and recrystallization. In addition, the model takes the dragging effect of precipitates on grain boundaries and dislocations into account, which leads to significant strengthening. For the microstructure description, a mean‐field approach is used. Due to the thermodynamic framework, the model is able to consistently predict the interplay between deformation, microstructure evolution, dynamic hardening and softening and the related temperature change. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A slip gradient crystal plasticity theory based on an extended energy flux
Authors: Prahs Andreas , Böhlke Thomas 
Published: March 2018

AbstractBased on a slip gradient crystal plasticity theory, cf. [1], an analytical, one dimensional solution for the plastic slip is discussed with respect to a homogeneous stress state. Multislip is considered in a bicrystal with two slip systems in each grain. The orientation of the grains is accounted for by the choice of a free energy based on the grain boundary Burgers tensor, cf. [2]. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental and Micro‐Macro Integrated FE Investigation of Texture and Microstructure Evolution in Polycrystalline Ag‐SnO2 Metal Matrix Composites
Authors: Schneider Yanling , Wasserbäch Werner , Schmauder Siegfried 
Published: March 2018

AbstractOur work is aimed to investigate the deformation behavior of Ag‐17vol.%SnO2 metal matrix composites under a hot extrusion process which causes extraordinarily large plastic deformations and recrystallization. The micro‐macro integrated axisymmetric finite element simulation is preferred for the first study, since it costs less calculation effort compared to 3D calculations, presents the mechanical variables in all 3D dimensions and the measured microstructure can be directly applied as the cross section. Due to that the volume (area) fraction of the particle phase in the selected 2D real microstructures often deviate from the real one, we show a numerical method to modify the EBSD‐images in order to match the 3D composition. This modification should be useful for FE simulations with a geometry based on a real microstructure. Considering that the tomograms are actually 2D images with a given distance in the 3rd dimension, such a modification with a further extension in the algorithm can also be applied for 3D microstructures based on tomograms to match the real composition. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Statistical characterization of granular material applied as crash absorber in ship building
Authors: Woitzik Christian , Chaudry Mohsin Ali , Wriggers Peter , Düster Alexander 
Published: March 2018

AbstractThis contribution deals with the determination of material parameters of lightweight granules, which will be used to increase the crashworthiness in ship construction. Using expanded glass or clay granules as a crash absorber requires a detailed knowledge about the single grain properties, such as Young's modulus or crushing strength. Therefore, a uniaxial compression test was performed and the results are covered with a statistical model consisting of nine parameters. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finite element simulation of nonlinear magnetoelectric coupling and damage behaviour in multiferroic composites
Authors: Avakian Artjom , Ricoeur Andreas 
Published: March 2018

AbstractIn this paper, the constitutive modelling of nonlinear multifield behavior as well as the finite element implementation are presented. Nonlinear material models describing the magneto‐ferroelectric or electro‐ferromagnetic behaviors are presented. Both physically and phenomenologically motivated constitutive models have been developed for the numerical calculation of principally different nonlinear magnetostrictive behaviors. Further, the nonlinear ferroelectric behavior is based on a physically motivated constitutive model. On this basis, the polarization in the ferroelectric and magnetization in the ferromagnetic and magnetostrictive phases, respectively, are simulated and the resulting effects analyzed. Additionally, the ferroelectric model accounts for damage due to microcrack growth. Numerical simulations focus on the calculation of magnetoelectric coupling and on the prediction of local domain orientations as well as damage processes going along with the poling process, thus supplying information on favorable electric‐magnetic loading sequences. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of the deformation‐dependent fluid flow in the fibrous gas diffusion layer of fuel cells
Authors: Chaaban Mohamad , Heider Yousef , Markert Bernd 
Published: March 2018

AbstractThe following contribution presents a numerical model for the description of the compression of gas diffusion layers (GDL) of polymer electrolyte membrane fuel cells (PEMFC). Proceeding from a macroscopic multiphasic modelling approach for porous materials, the work below instills the neo‐Hookean material law of finite deformations within the framework of the theory of porous media (TPM). Subsequently, the alteration in the deformation‐dependent intrinsic permeability is computed as an evaluation criteria of the effect of compression on the performance of the GDL. In furtherance of the affected transport property, a modified intrinsic permeability function is presented and validated to fit the profile of compression. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical methods for the modeling of the magnetization vector in multiferroic heterostructures
Authors: Dornisch Wolfgang , Schrade David , Wolf Jana , Müller Ralf 
Published: March 2018

AbstractMultiferroic heterostructures are commonly used to obtain electro‐magnetic coupling effects. Thereby, the ferroelectric layer is used to control the magnetization in the ferromagnetic layer. The coupling between the layers is obtained by the mechanical coupling between the layers, which have well‐defined interfaces. Within this contribution we use phase field models to define the polarization and magnetization in the ferroelectric and ferromagnetic layers, respectively. A coupling between polarization/magnetization and strains in each layer in combination with coherent deformations at the interface yields an electromagnetic coupling within the entire heterostructure. Numerical formulations for the interpolation of the polarization vector are well‐defined in the literature. However, the establishment of a consistent numerical formulation for the ferromagnetic layer, where the length of the magnetization vector has to be constant, remains a difficult task. We propose a new numerical approach for the consistent treatment of the ferromagnetic layer and provide numerical simulations which illustrate the electromagnetic coupling effect. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A coupled phase transformation and solute diffusion model for bainitic transformation
Authors: Düsing Martin , Mahnken Rolf 
Published: March 2018

AbstractIn materials science one distinguishes between upper and lower bainite, where both microstructures develop due to different diffusion processes. In this work we describe these different mechanisms with a new diffusion model coupled to a multiphase‐field equation. Numerical examples demonstrate the expected behavior. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modal Substructuring of Geometrically Nonlinear Plates
Authors: Karamooz Mahdiabadi Morteza , Buchmann Erhard , Rixen Daniel Jean 
Published: March 2018

AbstractThis work considers model reduction of geometrically nonlinear finite element (FE) model of a plate structure developed in a commercial FE package. The structure is first divided into smaller substructures. Since there is normally no access to the nonlinear stiffness tensors in FE packages, a non‐intrusive method is used in this paper to reduce the order of each substructure separately. In order to generate the nonlinear reduced order model (NLROM), the reduced substructures are assembled using the coupling procedure of the Component Mode Synthesis (CMS) method. As a linear basis, truncated free and fixed interface modes are used here to check the efficiency of the developed NLROM based on them. A plate structure subjected to large deflections is considered in this study to implement the substructuring method. For the sake of validation, Nonlinear Normal Modes (NNMs) are employed to check the convergence of NLROMs in a broadband frequency range. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiphysics of Tribocontacts
Authors: Ostermeyer Georg‐Peter , Bräuer Günter , Merlis Joshua , Kaestner Peter , Kipp Christian 
Published: March 2018

AbstractThe complex processes involved in the dry friction between two bodies are not yet fully understood. Towards an improved understanding of the associated tribological phenomena, the authors combine their skills and expertise in the respective fields of tribological experimentation, modeling, and simulation, as well as topological and chemical surface analyses. The aim of this research is more accurate predictions of the tribological behavior of minimal friction material mixtures. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)