bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparison of Algorithmic Approaches to Damage‐Plasticity Modeling in the Context of Gradient‐Enhancement
Authors: Kiefer Björn , Waffenschmidt Tobias , Sprave Leon , Menzel Andreas 
Published: October 2016

AbstractA gradient‐enhanced damage‐plasticity formulation is proposed, which prevents the loss of well‐posedness of the governing field equations in the post‐critical damage regime. The non‐locality of the formulation then manifests itself in terms of a free energy contribution that penalizes the occurrence of damage gradients. A second penalty term is introduced to force the global damage field to coincide with the internal damage state variable at the Gauss point level. An enforcement of Karush‐Kuhn‐Tucker (KKT) conditions on the global level can thus be avoided and classical local damage models may directly be incorporated and equipped with gradient enhancement. An important emphasis of this research is to investigate the efficiency and robustness of different algorithmic schemes to locally enforce the KKT conditions in the multi‐surface damage‐plasticity setting. Response simulations for a representative inhomogeneous boundary value problem are studied to assess the effectiveness of the gradient enhancement regarding stability and mesh objectivity. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of a Phase Field Model for Elasto‐plastic Fracture
Authors: Noll Timo , Kuhn Charlotte , Müller Ralf 
Published: October 2016

AbstractPhase field modelling of brittle fracture is very well understood today. However, the attempts of investigation of elasto‐plastic fracture by the phase field approach are limited. This contribution deals with the investigation of a phase field model for elasto‐plastic fracture. Based on a free energy density comprising elastic, fracture and plastic contributions, the model describes an extension of the linear elastic model towards von Mises plasticity. In this work it is analyzed numerically to which extend analytical findings concerning the interpretation of the model parameters in 1D are transferable to 2D scenarios. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parametric shape optimization of biaxial tensile specimen
Authors: Bauer Julian , Priesnitz Konstantin , Schemmann Malte , Brylka Barthel , Böhlke Thomas 
Published: October 2016

AbstractCommon cruciform specimen for biaxial tensile testing of sheet moulding compound, take damage and finally fail in uniaxially loaded areas. When using these specimen, an observation of damage initialization and failure in biaxially loaded areas is, therefore, not possible. In this paper, a parametric shape optimization is described to find a more suitable specimen shape. The parametrization of the specimen is presented. Objective functions are introduced to measure the appropriateness of specimen. A weighted summation transfers the constraint multiobjective optimization problem into a constraint scalar‐valued problem. Findings of experiments suggest that a specimen shape with straight, non‐tapering arms and slits along the arms is reasonable. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hydraulic fracturing with a simplified fluid model and XFEM
Authors: Schätzer Markus , Fries Thomas‐Peter 
Published: October 2016

AbstractIn hydraulic fracturing, the pressure exerted by the fracking fluid onto the surrounding solid, is typically obtained from solving the Reynolds equation. This is not always robust and leads to a complex behaviour at the crack front (toughness or viscous regimes). In the presented work, the Reynolds equation is replaced by a simplified fluid model, where pre‐defined pressure distributions are assumed which lead to a simpler and robust coupled problem. The surface integration of the fluid pressure onto the surrounding solid is outlined without any limitations on the distributions. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of short crack propagation under hydrogen influence using a hybrid boundary element technique for anisotropic elastic solids
Authors: Schippl Volker , Fritzen Claus‐Peter , Brück Sven , Christ Hans‐Jürgen , Schwarz Martina , Weihe Stefan 
Published: October 2016

AbstractA two‐dimensional model for stage I short crack propagation on multiple slip planes under the influence of hydrogen is presented. It considers elastic‐plastic material behaviour by allowing sliding on the active slip planes in the corresponding slip directions. A crack propagation law based on the crack tip sliding displacement is used to simulate crack growth. The activation of slip bands and the sliding on these active slip bands will be influenced by the local hydrogen concentration. The model is solved numerically using the boundary element method. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On configurational forces in a dynamic phase field model for fracturing
Authors: Schlüter Alexander , Kuhn Charlotte , Müller Ralf 
Published: October 2016

AbstractDynamic fracturing is an active field of research in which some phenomena like crack branching are only partly understood. The origin for most theoretical studies of fracturing ‐ analytical as well as numerical investigations ‐ are classical concepts of fracture mechanics such as Griffith's energy‐based description. The same is true for phase field fracture models that represent cracks by means of an additional scalar field. The evolution of this field can be found from minimization of a regularized energy functional which corresponds to a generalized Griffith criterion. This work discusses configurational forces as a means to highlight the relation between fracture evolution in a phase field model and the classical fracture mechanical concepts. In contrast to other numerical tools that rely on configurational forces to model the crack propagation, the configurational forces serve a different purpose in a phase field model for fracture. Here, they are a result of a post‐processing step that enhances the understanding of the simulated fracture problem. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A relaxation‐based approach to damage modeling
Authors: Schwarz Stephan , Junker Philipp , Hackl Klaus 
Published: October 2016

AbstractCommon material models that take into account softening effects due to damage have the problem of ill‐posed boundary value problems if no regularization is applied. This condition leads to a non‐unique solution for the resulting algebraic system and a strong mesh dependence of the numerical results. A possible solution approach to prevent this problem is to apply regularization techniques that take into account the non‐local behavior of the damage [1]. For this purpose a field function is often used to couple the local damage parameter to a non‐local level, in which differences between the local and non‐local parameter as well as the gradient of the non‐local parameter can be penalized. In contrast, we present a novel approach [2] to regularization that no longer needs a non‐local level but directly provides mesh‐independent results. Due to the new variational approach we are also able to improve the calculation times and convergence behavior. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Phase‐Field Model of Ductile Fracture at Finite Strains
Authors: Teichtmeister Stephan , Aldakheel Fadi , Miehe Christian 
Published: October 2016

AbstractThis work outlines a variational‐based framework for the phase field modeling of ductile fracture in elastic‐plastic solids at large strains. The phase field approach regularizes sharp crack discontinuities within a pure continuum setting by a specific gradient damage model with geometric features rooted in fracture mechanics. Based on the recent works [1, 2], the phase field model of ductile fracture is linked to a formulation of gradient plasticity at finite strains in order to ensure the crack to evolve inside the plastic zones. The thermodynamic formulation is based on the definition of a constitutive work density function including the stored elastic energy and the dissipated work due to plasticity and fracture. The proposed canonical theory is shown to be governed by a rate‐type minimization principle, which determines the coupled multi‐field evolution problem. Another aspect is the regularization towards a micromorphic gradient plasticity‐damage setting which enhances the robustness of the finite element formulation. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The stress state of the finite cylinder with the circular cracks
Authors: Vaysfeld Natalya , Protserov Yuriy 
Published: October 2016

AbstractThe axysimmetrical torsion problem for a finite cylinder with an arbitrary quantity of the cylindrical layers is solved. The cylinder is weaked by the parallel circular cracks in the first internal layer. The stated boundary valued problem problem is reduced to the system of the integro‐duferential equations solving with the help of the orthogonal polinomials method. The stress intensity factors (SIF) are obtained. The dependences of SIF values from the cracks' sizes, their location, and ratio of the layers' shear moduluses are concretized for the case of the two layers. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Nonlinear Deterministic Mode Decomposition Strategy for High‐Dimensional Monte Carlo Simulations
Authors: Bamer Franz , Markert Bernd 
Published: October 2016

AbstractWe present a new reduced Monte Carlo simulation strategy for nonlinear high‐order systems based on an extension of the proper orthogonal decomposition for transient excited structures. This novel approach enables the evaluation of the response statistics in a fractional amount of time compared to the full Monte Carlo simulation procedure. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The discontinuous Galerkin method with reduced integration scheme for the boundary terms in almost incompressible linear elasticity
Authors: Bayat Hamid Reza , Wulfinghoff Stephan , Reese Stefanie , Cavaliere Fabiola 
Published: October 2016

AbstractIn this paper, the discontinuous Galerkin (dG) method is introduced and applied for a problem of nearly incompressible material behavior, where the standard finite element method, namely the conventional continuous Galerkin (cG) method faces the well‐known problem of volumetric locking. The highlight of the work lies in the reduced integration scheme for the boundary terms of the dG method. Two different reduced and mixed integration schemes are presented and applied to reduce the calculation time. The dG method converges much faster than standard cG method with respect to the number of the elements, provided that the penalty value is sufficiently large. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Layer‐wise theory and finite elements for laminated poroelastic shells
Authors: Gfrerer Michael , Schanz Martin 
Published: October 2016

AbstractIn order to consider growing expectations on vibro‐acoustic performance of products within the design process, reliable simulation tools are necessary. In this paper, we present a approach for the simulation of laminated shells composed of elastic and poroelastic layers. We assume that the shell is given by a parametrization, which allows us to work witn the exact geometry. The three‐dimensional problem is reduced to a two‐dimensional one, by choosing a set of through‐the‐thickness functions for each quantity and through‐the‐thickness integration. The implemented high order finite element approach for the reduced problem on the reference surface relays on hierarchical shape functions. In a numerical example, we show the influence of poroelastic materials attached to a aluminium shell. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the performance of the Prange‐Hellinger‐Reissner finite element formulation for elasto‐plasticity at small strains
Authors: Igelbüscher Maximilian , Schröder Jörg , Schwarz Alexander 
Published: October 2016

AbstractThis contribution deals with a stress‐displacement mixed finite element formulation for elasto‐plasticity within the framework of small deformations based on the Prange‐Hellinger‐Reissner (PHR) functional. The interpolations for the displacements are given by standard Lagrangian shape functions and a 5‐parameter discontinuous interpolation is introduced for the stresses which was published by [1]. Based on the principle of maximum plastic dissipation the flow rule and hardening law will be derived by regarding a von Mises yield criterion, see [2]. In contrast to [3], we apply a point‐wise enforcement of the flow rule, hardening law and loading/unloading conditions. This work is related to the physically nonlinear mixed finite element based on the Prange‐Hellinger‐Reissner formulations for elasto‐plasticity, [4]. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure‐preserving space‐time discretization of nonlinear structural dynamics based on a mixed variational formulation
Authors: Janz Alexander , Betsch Peter , Hesch Christian 
Published: October 2016

AbstractThe present work deals with the design of structure‐preserving numerical methods in the field of nonlinear elastodynamics and structural dynamics. Structure‐preserving schemes such as energy‐momentum consistent (EMC) methods are known to exhibit superior numerical stability and robustness. Most of the previously developed schemes are relying on a displacement‐based variational formulation of the underlying mechanical model. In contrast to that we present a mixed variational framework for the systematic design of EMC schemes. The newly proposed mixed approach accomodates high‐performance mixed finite elements such as the shell element due to Wagner & Gruttmann [1] and the brick element due to Kasper & Taylor [2]. Accordingly, the proposed approach makes possible the structure‐preserving extension to the dynamic regime of those high‐performance elements. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A variational approach to modelling and optimization of viscoelastic structure motions
Authors: Kostin Georgy 
Published: October 2016

AbstractLocomotion of a flexible rack feeder consisting of two viscoelastic beams clumped on a mobile carriage are studied. The optimal control problem is to move the rack feeder from its initial state to terminal one in a fixed time and to minimize the mean mechanical energy of the system. The solution of the problem is based on the method of integro‐differential relations. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of Friction‐Induced Vibrations during Tightening of Bolted Joints
Authors: Baramsky Nicolaj , Seibel Arthur , Schlattmann Josef 
Published: October 2016

AbstractDuring the automated tightening process of bolted joints, the preload force can only be determined with greater effort. This is usually realized by using indirect methods, one of which is the torque‐controlled procedure. The dependency between the tightening torque and the preload force is deeply connected to the frictional conditions under the screw head and in the screw thread. Several methods exist to support the tightening process. Nonetheless, errors occur, which are, besides other reasons, due to friction‐induced vibrations. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extending the classification of devices in single‐degree‐of‐freedom vibrating systems
Authors: Franze Andreas 
Published: October 2016

AbstractThis contribution investigates existing descriptions of electro‐mechanical analogies and attempts of an extension by memristive elements. Therefore, the electro‐dynamical role of memristors is analyzed and translated into the context of system dynamics. This analysis leads to a generalized classification of devices for dynamical systems with a single degree of freedom (SDOF). (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the influence of the lamella's elasticity on self‐excited vibrations in gearboxes
Authors: Jehle Georg , Fidlin Alexander 
Published: October 2016

AbstractEek noise in a gearbox of a vehicle drivetrain is a phenomenon, which can arise while shifting between gears and which is not accepted by customers. Beneath audible squeaking, it can cause damage of mechanical components. There is a wide range of possible reasons for the occurrence of this effect, which strongly depends on properties of the considered gearbox (physical parameters, geometry, operation, …). From the mathematical point of view, the occurrence can be predicted using linear stability analysis of the stationary behaviour of a physically motivated gearbox model.The components of a gearbox are clutch discs being in contact, gears and elastically supported shafts. In this contribution, a rigid multibody model of the device [4] is extended by the elastic modelling of the motor's side disc (rotating Kirchhoff plate). The aim of the overall system is to analyze the shifting process.The analysis reveals that beneath instability mechanisms which are known from systems with rigid bodies, new instabilities occur incorporating of out‐of‐plane vibrations of the plate. In a reasonable parameter region, the first two unsymmetrical modes of the lamella have the main contribution to the instability. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An extended LuGre friction model incorporating frictional aging
Authors: Krasmik Viktor , Schlattmann Josef 
Published: October 2016

AbstractIn this contribution, the LuGre model is extended and the effect of frictional aging is incorporated using the state variable approach. The adapted friction model is used in combination with a single‐degree‐of‐freedom oscillator to investigate the basic effects on the stick‐slip amplitude and period. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of micro‐cutting considering finite deformation crystal plasticity
Authors: Bischof Robert , Schneider Frank , Kuhn Charlotte , Aurich Jan C. , Müller Ralf 
Published: October 2016

AbstractMicro‐machining processes on metalic microstructures are influenced by the crystal structure, i. e. the grain orientation. Furthermore, the chip formation underlies large deformations. To perform finite element simulations of micro‐cutting processes, a large deformation material model is necessary in order to model the hyperelastic and finite plastic material behaviour. In the case of cp‐titanium material with hcp‐crystal structure the anisotropic behaviour must be considered by an appropriate set of slip planes and slip directions. In the present work the impact of the grain orientation on the plastic deformation is demonstrated by means of finite element simulations of a finite deformation single slip crystal plasticity model. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental and numerical investigation of PUR foam under dynamic loading
Authors: Bogunia Lukas , Weinberg Kerstin 
Published: October 2016

AbstractVarious factors may subject buildings to shock which continues in their structure and is perceived by the people living in them as noticeable vibrations or noise. In this context, polyurethane (PUR) foams, which have been developed to isolate vibrations, have shown to be very effective in practical use. However, whereas static properties of open‐cell structures have already been determined numerically in good agreement to experimental results, cf. [1], there are hardly any investigations on the dynamical properties characterizing acoustic damping.In order to validate experimental measurements of eigenfrequencies for different PUR foam specimen we present here a strategy to reproduce the foam behavior numerically. In doing so, PUR foams are modeled using a three dimensional Voronoi‐tessellation technique. The resulting Voronoi cells correspond to open pores and are scaled in such a way that the volume ratio between the pores and material matches the given PUR foam. For finite element analysis the connections between the cells are modeled as beam elements, the beam shape follows Bezièr curves. The generated model is analyzed with a finite element software and the dynamical parameters are determined. The numerical results are compared to our experimental data. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular statics simulations of ferroelectric nanofilms
Authors: Endres Florian , Steinmann Paul 
Published: October 2016

AbstractSmart materials are of great interest not only for scientific, but also for technological reasons due to ongoing miniaturization and rapid developments in manufacturing technologies of nanocomponents [1]. Therefore, simulations on the nanometer length scale are becoming more important in order to fundamentally understand and predict the complex material behavior of ferroelectric nanocomponents, such as ferroelectric nanofilms or nanowires. We apply a previously developed extended molecular statics algorithm [2] to simulate ferroelectric barium titanate nanofilms. The algorithm is able to also consider mechanical stress explicitly whereas most molecular simulations of ferroelectrics are restricted to NVT‐ensembles. We simulate a stress relaxed ultra thin barium titanate film and apply compressive strain in order to investigate size effects of ferroelectric nanofilms. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On intrinsic time measure concept with application to the modeling of smart materials
Authors: Ioan Rodica , Ioan Stefan 
Published: October 2016

AbstractIn this paper, the cyclic behavior of a Nitinol cubic block is described by using the Bouc‐Wen model [2] coupled to the intrinsic time measure, other than the clock time which governs the behavior of the materials [4]. The modified Bouc‐Wen model consists from the classical Bouc‐Wen model coupled to the intrinsic time measure, other than the clock time which governs the behaviour of the materials. As a consequence, the thermodynamic admissibility of the Bouc–Wen model is provided by the endochronic theory of plasticity. The role of the intrinsic time measure is described by capturing the stiffness and strength degradation and the opposite phenomena. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling additive manufactured materials using a crystal plasticity model
Authors: Kergaßner Andreas , Mergheim Julia , Steinmann Paul 
Published: October 2016

AbstractIn this contribution the macroscopic behaviour of additively manufactured Inconel 718 will be identified using a crystal plasticity model on the meso‐level. The experimentally observed grain structures will be used to generate a representative volume element. Based on this RVE macroscopic mechanical parameters will be identified and compared with experimental results. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Large strain transversely isotropic viscoplasticity by directly connected rheological elements
Authors: Kießling Robert , Ihlemann Jörn 
Published: October 2016

AbstractPrecise material models at large strains for the components of an intrinsic hybrid composite, such as a fibre‐matrix composite, are required to perform finite element simulations. This contribution considers the development of a transversely isotropic viscoplastic material model to predict the mechanical behaviour of a polymer matrix with unidirectional fibre‐reinforcement. To this end, a rheological model of the matrix material is deduced from the phenomenological description of an unreinforced polymer. The application of a concept, which enables material modelling at large strains by directly connected rheological elements, yields the according viscoplastic material model. Based on the results of finite element simulations of a representative volume element consisting of a polymer matrix and a fibre constituent, the matrix's material model is modified by an anisotropic extension, which results in a homogenised viscoplastic material model for an unidirectional fibre‐matrix composite. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)