bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the local behavior of different cohesive zone models
Authors: Balzani Claudio 
Published: December 2012

AbstractCohesive interface elements are well suited for three‐dimensional crack propagation analyses as long as the crack path is known. This is the case e.g. in delamination analyses of laminated composite structures or failure analyses of adhesively bonded joints. Actually, they are widely used in such applications for both brittle and ductile systems.As long as the strength and fracture toughness of the material are accurately captured it is generally accepted that the shape of the cohesive law has little to no influence on the mechanical behavior of the investigated structures. However, when having a look on the local behavior of different cohesive zone models, such as stress distribution in the fracture process zone, the results exhibit certain differences. These will be studied in the present contribution. Especially the local stress distribution will be investigated and the effect on the computational efficiency will be pointed out. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coupled multiscale finite element analysis of shell structures
Authors: Hebel Jochen , Gruttmann Friedrich , Wagner Werner 
Published: December 2012

AbstractIn this paper, a coupled two‐scale shell model is presented. A variational formulation and associated linearisation for the coupled global‐local boundary value problem is derived. The discretisation of the shell is performed with quadrilaterals, whereas the local boundary value problems at the integration points of the shell are discretised using 8‐noded or 27‐noded brick elements, or solid shell elements. The coupled boundary value problem is simultaneously solved within a Newton iteration scheme. Solutions for small strain problems are computed within the so‐called FE2 method. In an important test, the correct material matrix for the stress resultants assuming linear elasticity and a homogeneous continuum is verified. Examples show that the developed two‐scale model is able to analyse the global and local mechanical behaviour of heterogeneous shell structures. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of notches and cracks in circular Kirchhoff plates using the scaled boundary finite element method
Authors: Dieringer Rolf , Becker Wilfried 
Published: December 2012

AbstractA new formulation of the scaled boundary finite element method (SBFEM) is presented for the analysis of circular plates in the framework of Kirchhoff's plate theory. Essential for the SBFEM is, that a domain is described by the mapping of its boundary with respect to a scaling centre. The governing partial differential equations are transformed into scaled boundary coordinates and are reduced to a set of ordinary differential equations, which can be solved in a closed‐form analytical manner. If the scaling centre is selected at the root of an existent crack or notch, the SBFEM enables the effective and precise calculation of singularity orders of cracked and notched structures. The element stiffness matrices for bounded and unbounded media are derived. Numerical examples show the performance and efficiency of the method, applied to plate bending problems. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An Efficient Scheme for Stochastic Finite Element Solutions
Authors: Jablonski Philipp‐Paul , Nackenhorst Udo 
Published: December 2012

AbstractThe Polynomial Chaos expansion in Stochastic Finite Element Methods increases the size of the resulting linear systems dramatically. In iterative scheme which takes the underlying statistics into account is suggested for the efficient numerical solution. Additionally, an approach for the solution of von Mises stresses from the Polynomial Chaos representation of the displacement field is outlined. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaptive FEM with Stabilized Elements for Parameter Identification of Incompressible Hyperelastic Materials
Authors: Widany Kai‐Uwe , Mahnken Rolf 
Published: December 2012

AbstractThis work is concerned with the identification of material parameters for isotropic, incompressible hyperelastic material models. Besides the principal stretch‐based strain‐energy function by Ogden an invariant‐based strain‐energy function by Rivlin/Saunders is considered for which parameter sensitivities are derived. The identification is formulated as a least‐squares minimization problem based on the finite element method to account for inhomogeneous states of stresses and strains in the experimental data which is obtained by optical measurements. For the finite element method low‐order tetrahedral elements in a mixed displacement‐pressure formulation with stabilization are considered. Special attention is payed to an adaptive mesh‐refinement based on a goal‐oriented a posteriori error indicator to gain reliable material parameters. To approximate error terms an element‐wise recovery technique based on enhanced gradients is introduced. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solving hyperelastic problems using mixed LSFEM
Authors: Steeger Karl , Schwarz Alexander , Schröder Jörg , Starke Gerhard , Müller Benjamin 
Published: December 2012

AbstractThe focus of this contribution is the solution of hyperelastic problems using the least‐squares finite element method (LSFEM). In particular a mixed least‐squares finite element formulation is provided and applied on geometrically nonlinear problems. The basis for the element formulation is a div‐grad first‐order system consisting of the equilibrium condition and the constitutive equation both written in a residual form. An L2‐norm is adopted on the residuals leading to a functional depending on displacements and stresses which has to be minimized. Therefore the first variations with respect to both free variables have to be zero. The solution can then be found by applying Newton's Method. For the continuous approximation of the displacements in W1,p with p > 2, standard polynomials are used. Shape functions belonging to a Raviart‐Thomas space are applied for the stress interpolation. These vector‐valued functions ensure a conforming discretization of the Sobolev space H(div, Ω). Finally the proposed formulation is tested in a numerical example. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of the coupling effects of the longitudinal and transverse displacements on the deformation and internal forces of functionally graded beams
Authors: Villamil Pedro , Zhang Chuanzeng , Chen Weiqiu 
Published: December 2012

AbstractFunctionally graded beams (FGBs) with an arbitrary gradation of the material properties along the thickness of the beams are analyzed. Such FGBs are of special interest in civil and mechanical engineering to improve both the thermal and the mechanical behaviour of the beams. In [1] and [3] free vibrations of functionally graded Timoshenko and Euler‐Bernoulli beams have been considered. The obtained analytical solutions are based on the work of Li [2], where closed‐form solutions of stress distributions, eigenfrequencies and eigenfunctions have been derived by means of a single differential equation of motion for the deflection. However, these previous works did not take into account the coupling between the longitudinal and the transverse displacements and its effects on the deformation and internal forces of the FGBs. This approach is appropriate only for a symmetrical material gradation but it may not be valid for general cases with an arbitrary material gradation.In this paper, the coupling effects of the longitudinal and transverse displacements on the deformation and internal forces of FGBs are investigated for different beam support conditions. Analytical solutions of the corresponding boundary value problem are derived. A comparison is also made with the numerical results obtained by the finite element method (FEM). (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stress concentrations at free edges of shear webs
Authors: Kralovec Christoph , Schagerl Martin , Schröder Kai‐Uwe 
Published: December 2012

AbstractThis article analyzes the stress‐state of a shear web with free edges, i.e. a rectangular plate, which is loaded by shear on two simply supported opposite edges whereas the other two opposite edges can move freely and remain unloaded. Considering the plate's plane stress‐state it is obvious that at the corners the maximum equivalent stress occurs. If the plate does not buckle this stress determines its strength. However, the evaluation of the stress‐state at the corners raises some difficulties. As at these points the loaded and unloaded edges meet, the development of stress concentrations is indicated. Here the fundamental question arises if these stress concentrations remain finite or if singularities occur. To analyze this question we use both, analytical and numerical considerations. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Shaking table tests of a model‐scale building with 2DOF pendulum mass damper
Authors: Majcher Krzysztof 
Published: December 2012

AbstractIn this paper, the numerical and experimental studies of a tall building's model with 2DOF pendulum mass damper (PMD) are considered. It is assumed that the model excitation is in the form of horizontal and/or torsional motion of the ground caused by earthquake.The construction consists of the main system (tall building's model) and a double pendulum mass damper, which is attuned to the first (bending) and the second (torsional) eigenfrequencies of the main structure. The analysis focuses on reduction of structure vibration caused by horizontal or torsional component of ground motions. Therefore, results presented in this work show efficiency of 2DOF PMD for vibration reduction.The numerical analysis of the problem is performed with using COSMOS/M system (a FEM numerical model is defined), while experimental analysis is carried out on a physical model‐scale building with 2DOF PMD. Model consists of twenty five recurrent storeys (height 2.5m) with a PMD located on the highest one. Shaking table device is used to simulate an earthquake excitation in horizontal and torsional component, independently. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Material libraries for texturized thin metal sheets in elastic range
Authors: Montalvo‐Urquizo Jonathan 
Published: December 2012

AbstractAn approach for the simulation of the elastic material responses using stochastic generation of material samples and a subdomain‐based FEM simulation is presented. Both the single‐grain geometries and the lattice orientations are stochastically simulated. This simulations can be used to build a Material Library of responses which must be computed only once for a given material. Furthermore, the Library can be used in a fast two‐scale simulation avoiding any detailed computation in the microscale. In this contribution, the basic ideas of the computational algorithm are presented and some results of the material library for Steel DC01 are given. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hysteresis Effects in Abrasive and Frictional Contacts
Authors: de Payrebrune Kristin Miriam , Kröger Matthias 
Published: December 2012

AbstractGrinding is a very complex and high dynamical material removal process with stochastically distributed grain engagements and strong varying local contact conditions. Over a long time only macroscopic effects are analyzed and predicted by empirical relations. To understand the dynamical behavior also local effects must be considered.Therefore, the local contact conditions and especially the time‐dependent friction coefficient are analyzed. One detected effect is the dependency of the friction coefficient on the normal forces and on their time history, so a hysteresis loop occurs for increasing and decreasing values. With the force dependent friction coefficient local and dynamic effects are physically interpretable. In contrast, the global mean friction coefficient is constant over the entire force range which describes only quasi‐stationary effects. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Semi‐Analytical Method of Solving the Fokker‐Planck‐Equation for High‐Dimensional Nonlinear Mechanical Systems
Authors: Martens Wolfram 
Published: December 2012

AbstractStochastic processes are a common way of describing systems that are subjected to random influences. Technical systems may be excited by road roughness or wind gusts, for example, as well as fluctuating system parameters, which can all be described by stochastic differential equations. In previous works by the author and others (see [1], for example) it has been demonstrated how a Galerkin‐method can be used to obtain global numerical solutions of the Fokker‐Planck‐Equation (FPE) for nonlinear random systems. Computational efforts are reduced by orthogonal polynomial expansion of approximate solutions so that probability density functions (pdfs) for comparably high‐dimensional problems have been computed successfully. Stationary mechanical systems with dimensions up to d = 10 have been investigated, including polynomial as well as non‐smooth nonlinearities. This article presents results for different energy‐harvester‐systems under stochastic excitation, a field of research that has become the subject of increasing attention in the last years. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rotor Stator Interaction with Many Degrees of Freedom
Authors: Alber Oliver 
Published: December 2012

AbstractA many‐degrees‐of‐freedom model of rotor stator contact is presented. The stability analysis of the synchronous motion of the simple JEFFCOTT rotor contacting a single‐mass stator is extended to systems with many degrees of freedom. The stationary synchronous motion as well as its stability are validated by direct numerical integration of the differential equations. The resulting dynamics is exemplified in two examples, which may be quite different than the dynamics of the simple JEFFCOTT rotor. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of viscous damping on friction induced travelling waves
Authors: Steindl Alois 
Published: December 2012

AbstractWe investigate the influence of viscous damping on the shape and stability of travelling waves induced by Coulomb friction between a rotating rigid shaft and an annular elastic cylinder. As expected, the damping causes the travelling wave solutions to become smoother and more stable. It also decreases the amplitude and range of separation solutions and may destroy the travelling waves by grazing bifurcations at large values of the damping parameters. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Phase Field Model for Martensitic Transformations
Authors: Schmitt Regina , Müller Ralf , Kuhn Charlotte 
Published: December 2012

AbstractThe martensitic transformation is described using a phase field model which is in mathematical terms the regularization of a sharp interface approach. In this work, up to two martensitic orientation variants are considered. The evolution of microstructure is assumed to follow a time dependent Ginzburg‐Landau equation. The coupled problem of the mechanical balance equation and the evolution equations is solved using finite elements and an implicit time integration scheme. In this work, the global energy evolution during the martensitic transformation and the influence of external loads on the formation of the different martensitic phases are studied in 2d. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On two different inverse form finding methods for hyperelastic and elastoplastic materials
Authors: Germain Sandrine , Steinmann Paul 
Published: December 2012

AbstractThis contribution focuses on two different developments of mechanical‐computational methods for the optimal determination of the initial shape of formed functional components knowing the deformed configuration, the applied loads and the boundary conditions. The first method uses an inverse mechanical formulation and can be applied to materials with hyperelastic behaviors. For materials with elastoplastic properties this method is not advocated, without knowing the final plastic strains, due to the non uniqueness of the solution. The second method uses a shape optimization formulation in the sense of an inverse problem via successive iterations of the direct problem. For hyperelastic materials the inverse mechanical formulation is preferred for its velocity and the non exhibition of possible mesh distortions. In the shape optimization formulation mesh distortions can be avoided by an update of the reference configuration of the functional part. Both methods are using a formulation in the logarithmic strain space. A numerical example for materials with isotropic elastoplastic behaviors illustrates the shape optimization formulation. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The boundary value problems of the full coupled theory of poroelasticity for materials with double porosity
Authors: Svanadze Merab 
Published: December 2012

AbstractIn this paper the full coupled quasi‐static theory of poroelasticity for materials with double porosity is considered. The basic boundary value problems (BVPs) of the steady vibrations are investigated. The uniqueness theorems of the internal BVPs of steady vibrations are proved. The basic properties of elastopotentials are established. The existence of regular solutions of the BVPs by means of the boundary integral equations method and the theory of singular integral equations is proved. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of predeformation‐ and frequency‐dependent material behaviour of filled rubber under large predeformations superimposed with harmonic deformations of small amplitudes
Authors: Wollscheid Daniel , Lion Alexander 
Published: December 2012

AbstractViscoelastic materials show a significant frequency and predeformation dependent behaviour under loadings consisting of large predeformations superimposed by small harmonic deformations. Based on further material models of Haupt & Lion [1] and Lion, Retka & Rendek [2] we introduce a recently developed constitutive approach of finite viscoelasticity in the frequency domain that is able to describe the frequency and predeformation dependent material behaviour with respect to storage and loss modulus. The constitutive equations are geometrically linearised in the neighbourhood of the predeformation and will be evaluated in the frequency domain. Furthermore a formulation for incompressible material behaviour is introduced and the corresponding dynamic modulus tensors are derived. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface Roughness Effects in Nanoindentation of Soft Polymers
Authors: Chen Zhaoyu , Diebels Stefan 
Published: December 2012

AbstractIn the present paper, the surface roughness effects in nanoindentation of soft polymers are modelled numerically based on the approach utilising the phenomenological concepts. A real surface topography is characterised by using multi‐level of protuberance‐on‐protuberance profiles. Following the real surface topography is simplified by one‐level or multi‐level sine curve profiles. Finally, the surface roughness effects are quantified related to the force‐displacement data as well as to the identified material parameters. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A vanishing viscosity approach to the evolution of microstructures in finite plasticity
Authors: Günther Christina , Hackl Klaus 
Published: December 2012

AbstractMaterial microstructures in finite single‐slip crystal plasticity occur and evolve due to deformation. Their formation is not arbitrary, they tend to form structured spatial patterns. This hints at a universal underlying process. As in the approach of D. Kochmann and K. Hackl, we use a variational framework, focusing on the Lagrange functional to describe the evolving mircrostructure. We modify this approach by introducing a small smooth transition zone between the domains in order to improve the numerical treatment. We present explicit time‐evolution equations for the volume fractions and the internal variables. We outline a numerical scheme. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the direct connection of rheological elements in nonlinear continuum mechanics
Authors: Landgraf Ralf , Ihlemann Jörn 
Published: December 2012

AbstractThe structure of complicated phenomenological material models at finite strains is often exemplified with the help of rheological elements. Thereby, simple material behaviour, i.e. elasticity or viscous and plastic flow, are composes by components. In our approach, we directly apply this concept to obtain material models at finite strains. Towards this end, the thermodynamically consistent material behaviour of single elements is defined first. Subsequently, the elements are connected by evaluation of stress equilibria equations formulated on interconnecting configurations. The basic equations of this concept are presented using the example of nonlinear viscoelasticity of Maxwell type. The model results from a series connection of an elastic and a viscous element, whereas both are formulated in a thermodynamically consistent way within the framework on nonlinear continuum mechanics. Furthermore, an approach of numerical implementation using the stress equilibria is suggested. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multi‐phase modeling of shape memory polymers
Authors: Hempel Nico , Böl Markus 
Published: December 2012

AbstractIn the present work, we propose a model for shape memory polymers based on the idea of the multiplicative decomposition of the deformation gradient. Evolution equations for the several deformation components are presented that provide for the storage of the entropy‐elastic strain and its recovery during the transition between the frozen phase and the active phase. First characteristic shape memory cycles for small and large deformations will be shown as a last point. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Formulation of Finite Gradient Crystal Plasticity with Systematic Separation of Long‐ and Short‐Range States
Authors: Mauthe Steffen , Hildebrand Felix , Miehe Christian 
Published: December 2012

AbstractWith the ongoing trend of miniaturization and nanotechnology, the predictive modeling of size effects plays an increasingly important role in metal plasticity. The description of such size effects requires gradient‐extended theories of crystal plasticity. We outline a new viscous regularized formulation of rate‐independent gradient crystal plasticity for full multislip scenarios. To this end, we exploit in a systematic manner the long‐ and short‐range nature of the involved variables. It is shown that the evolution of the short‐range state is fully determined by the evolution of the long‐range state. This separation into long‐ and short‐range states is systematically exploited in the algorithmic treatment by a new update structure, where the short‐range variables play the role of a local history base. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)