bluuebunny/crossref_metadata_2025_split huggingface dataset:
Second‐order time‐integration in inelastic dynamical systems
Authors: Grafenhorst Matthias , Hartmann Stefan , Rang Joachim 
Published: December 2014

AbstractIn structural dynamics the initial boundary value problem has to be solved in the space and time domain. The spatial discretization is done using finite elements. For the temporal discretization two classes of Runge‐Kutta methods and the generalized‐α method are compared. The representatives for the Runge‐Kutta methods are diagonally implicit Runge‐Kutta schemes (DIRK) and diagonally implicit Runge‐Kutta‐Nyström schemes (DIRKN). (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Contact of ropes and orthotropic rough surfaces
Authors: Konyukhov Alexander 
Published: December 2014

AbstractContact between arbitrary curved ropes and arbitrary curved rough orthotropic surfaces has been revised from the geometrical point of view. Variational equations for the equilibrium of ropes on orthotropic rough surfaces are derived, first, using the consistent variational inclusion of frictional contact constraints via Karush‐Kuhn‐Tucker conditions expressed in Darboux basis. Then, the systems of differential equations are derived for both statics and dynamics of ropes on a rough surface depending on the sticking‐sliding condition for orthotropic Coulomb's friction. Three criteria are found to be fulfilled during the static equilibrium of a rope on a rough surface: “no separation”, condition for dragging coefficient of friction and inequality for tangential forces at the end of the rope. The limit tangential loads still preserve the famous “Euler view” T = T0eωs for the curves and surfaces of constant curvature. It is shown that the curve of the maximum tension of a rough orthotropic surface is geodesic. Equations of motion are derived in the case if the sliding criteria is fulfilled and there is “no separation”. Various cases possessing analytical solutions of the derived system, including Euler case and a spiral rope on a cylinder are shown as examples of application of the derived theory. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Two Dimensional Model for the Dynamical Contact of Elastic Rough Surfaces
Authors: Neuhaus Jan , Sextro Walter 
Published: December 2014

AbstractTo model the contact behavior including dynamical effects, a two dimensional mechanical model of elastic rough contact is developed. This model can simulate the contact behaviour between two rough surfaces depending on normal pressure, sliding speed and roughness profiles. The contact between two rough surfaces is reduced to a rough rigid and a rough elastic layer. The elastic layer is modeled by point masses connected by spring‐damper elements. The total system is described by coupled ODEs. The number of ODEs and thus the degree of freedom of the model depends on the varying contact conditions. The contact conditions are monitored during the simulation and the simulation interrupts, in case the contact conditions change. The equations of motion are then adapted with respect to the contact constraints. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experiments, modelling and simulation of adhesive curing processes in bonded three dimensional curved piezo metal composite structures
Authors: Rudolph Martin , Landgraf Ralf , Scherzer Robert , Ihlemann Jörn 
Published: December 2014

AbstractThis contribution deals with the modelling and simulation of curing phenomena in adhesively bonded piezo metal composites which consists of a piezoelectric module enclosed by an adhesive layer which in turn is surrounded by two metal sheets. A short survey on the neccessary experimental investigations to characterise the adhesive's material behaviour is given and important aspects on the corresponding phenomenological modelling approach are presented. Both steps take into account the curing reaction, changes of volume, like chemical shrinkage, and inelastic mechanical behaviour which is temperature and curing dependent. Finally, the simulation strategy for the modelling within a finite element environment is depicted. By this, residual stresses, secondary deformations and loads on the piezo modules can be predicted, which is exemplified by a comparative study verifying a novel manufacturing strategy. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Particle Finite Element Analysis of Cutting Processes
Authors: Sabel Matthias , Sator Christian , Müller Ralf 
Published: December 2014

AbstractAlthough machining is a well established method in manufacturing, the numerical modeling is complicated since severe changes in the geometry and the topology can occur. Especially the formation of chips and burrs requires a method that tracks the large configurational changes. The particle finite element method (PFEM) combines the benefits of the standard finite element method (FEM) and discrete models, such as molecular dynamics simulations and is therefore well suited to cope with these tasks. In this article, a description of the conceptual realisation and the overall algorithm is given and a numerical analysis of a cutting process is performed. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Approximation of the dual problem for error estimation in inelastic problems
Authors: Widany Kai‐Uwe , Mahnken Rolf 
Published: December 2014

AbstractIn numerical simulations with the finite element method the dependency on the mesh – and for time‐dependent problems on the time discretization – arises. Adaptive refinements in space (and time) based on goal‐oriented error estimation [1] become more and more popular for finite element analyses to balance computational effort and accuracy of the solution. The introduction of a goal quantity of interest defines a dual problem which has to be solved to estimate the error with respect to it. Often such procedures are based on a space‐time Galerkin framework for instationary problems [2]. Discretization results in systems of equations in which the unknowns are nodal values. Contrary, in current finite element implementations for path‐dependent problems some quantities storing information about the path‐dependence are located at the integration points of the finite elements [3], e.g. plastic strains etc. In this contribution we propose an approach – similar to [4] for sensitivity analysis – for the approximation of the dual problem which mainly maintains the structure of current finite element implementations for path‐dependent problems. Here, the dual problem is introduced after discretization. A numerical example illustrates the approach. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of a Bolted Friction Resonator in the Frequency Domain
Authors: Süß Dominik , Willner Kai 
Published: December 2014

AbstractJoints play an important role in most mechanical applications and the prediction of the dynamical behavior of jointed structures is a challenging task in structural dynamics. Their inclusion leads to, for example, shifts of the resonance frequencies or of the maximal response amplitude within a resonance due to damping effects. In this paper, the focus is on investigating the behavior of a jointed structure within the frequency domain corresponding to the stationary behavior of the system in the time domain. Here the Harmonic Balance Method (HBM) is applied to a friction oscillator containing a bolted lap joint. This structure is modeled on two different ways via Finite Element models with a corresponding three dimensional contact law. The results for the different models are compared to each other. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parameterreduktion am Reibschwinger durch Ähnlichkeitskennzahlen
Authors: Kröger Matthias , de Payrebrune Kristin M. 
Published: December 2014

AbstractEs ist in der mathematischen Auswertung von Bewegungsgleichungen üblich, durch Umformungen und Transformationen die zu untersuchende Parameteranzahl zu reduzieren. Ein Beispiel ist die Transformation in die Eigenzeit. Am Reibschwinger mit Coulomb'scher Reibkennlinie oder linear mit der Relativgeschwindigkeit fallender Reibkennlinie sind zahlreiche Parame‐terreduktionen durch derartige Transformationen möglich. Allerdings muss der Anwender dabei neben der mathematischen Interpretation auch die physikalische Interpretation der Lösung beachten. Dann ist es möglich, den Aufwand für Parameteranalysen relativ gering zu halten. Eine größere Herausforderung ergibt sich, wenn der Reibschwinger fremd‐ und selbsterregt ist oder mehrere Reibelemente gekoppelt werden. Diese Arbeit stellt die Grundlagen und deren Übertragung auf komplexere Reibschwinger vor. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of Strain Gradient Plasticity to Micro‐torsion Experiments
Authors: Bayerschen Eric , Wulfinghoff Stephan , Böhlke Thomas 
Published: December 2014

AbstractThe applicability of a strain gradient crystal plasticity model to size effects observed on microwires in torsion experiments is discussed. Finite Element simulations of simplified cylindrical grain aggregations are presented and the resulting overall mechanical response is compared to experimental data for gold from the literature. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Constitutive modelling of thermo‐viscoelastic‐plastic behaviour of adhesively bonded joints
Authors: Kühlmeyer Patrick , Matzenmiller Anton 
Published: December 2014

AbstractFor ductile structural adhesives under thermal and mechanical loading, a thermo‐viscoelastic‐plastic interfacial constitutive model is introduced using a generalised MAXWELL solid in series with a thermal strain element and a ST.‐VENANT body with isotropic hardening for plasticity. The temperature dependency of the viscosity is taken into account on assuming thermorheologically simple material behaviour, while the yield threshold and the hardening parameters depend on empirical functions of temperature. Numerical examples for the model verification and validation are discussed. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of Viscoelastic Properties and Damaging Effects of Highly Extensible Polyurea
Authors: Reppel Thomas , Decker Johann , Weinberg Kerstin 
Published: December 2014

AbstractThe present work aims particular at the experimental identification of the viscoelastic properties of polyurea as well as on the onset of the damage.For the viscoelastic part, several relaxation experiments are performed. From the measured data a general viscoelastic model is derived where we use two different approaches. At first we identify a general Maxwell model (combining spring and damping elements for finite deformations) to use a prony series with N elements, which requires the identification of 2N + 1 parameters. At second, a model of generalized fractional elements [3] is employed. Both approaches are studied in detail and are compared to data from literature; furthermore a comparison concerning the effort is presented.Damaging effects of Polyurea are investigated using tensile tests with and without cyclic loading. In particular we focus on the the onset of damage by cavitation. To this end the recovered specimens were analyzed using a laser microscope; the surfaces of the ruptured areas are compared in terms of quantity and size of voids. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cyclic yield strength in definition of design limits for fatigue and creep
Authors: Gorash Yevgen , MacKenzie Donald 
Published: December 2014

AbstractThis study proposes a cyclic yield strength (CYS, σcy) as a key characteristic for the definition of safe design for engineering structures operating under fatigue and creep conditions. CYS is defined on a cyclic stress‐strain curve, while monotonic yield strength (MYS, σmy) is defined on a monotonic stress‐strain curve. Both values of σcy and σmy are identified using a 2‐steps fitting procedure of the experimental stress‐strain curves using Ramberg‐Osgood and Chaboche material models. Comparison of σcy and fatigue endurance limit σflim on the S‐N fatigue curve reveals that they are approximately equal. Hence, basically safe fatigue design is guaranteed in purely elastic domain defined by the σcy. A typical creep rupture curve in time‐to‐failure approach for creep analysis has 2 inflections corresponding to the σcy and σmy. These stresses separate 3 sections on the creep rupture curve, which are characterised by 3 different creep fracture modes and 3 creep deformation mechanisms. Thus, basically safe creep design is guaranteed in linear creep domain with brittle failure mode defined by the σcy. These assumptions are confirmed for several structural low‐ and high‐alloy steels for normal and high‐temperature applications. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magneto‐Sensitive Elastomers: An Experimental Point of View
Authors: Walter Bastian , Saxena Prashant , Kaschta Joachim , Schubert Dirk W. , Steinmann Paul 
Published: December 2014

AbstractMagneto‐sensitive elastomers (MSEs) are smart materials changing their shape and mechanical properties in the presence of a magnetic field. Focussing on model systems, silicone based MSEs are prepared by a multi‐step mixing process and characterised using a rotational rheometer (plate‐plate). Data obtained by relaxation tests is used to set‐up a material model coupling the theories of viscoelasticity and magnetoelasticity. The behaviour of MSEs in quasi‐static and dynamic mechanical shear experiments can be successfully predicted by the analytical model using parameters received by fitting the transient experiments. The model is validated for small shear deformations (γ = 0.02) and low magnetic fields (𝔹 = 0.2 T). (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A variational approach towards the modeling of equilibrium twin interfaces in a single‐crystalline magnetic shape memory alloy sample
Authors: Wang Jiong , Steinmann Paul 
Published: December 2014

AbstractIn this work, a variational approach is proposed to study the magneto‐mechanical response of a single‐crystalline MSMA sample. By proposing a total energy functional for the whole magneto‐mechanical system, the governing PDE system is derived by calculating the variations of the total energy functional with respect to the independent variables. An iterative numerical algorithm is proposed to solve the governing PDE system. As an example, a MSMA sample with cuboid shape and subject to perpendicularly applied magnetic and mechanical loadings is considered. It can be seen that the magneto‐mechanical response of this sample can be predicted at a quantitative level. The whole procedure of variant reorientation in the sample can also be simulated. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of Multi Wall Carbon Nanotubes and Nanotube assemblies by a molecular mechanics approach
Authors: Eberhardt Oliver , Guenther Margarita , Wallmersperger Thomas 
Published: December 2014

AbstractThe present work describes the modeling techniques applied for the investigation of assemblies of Carbon Nanotubes (CNTs) and Multi Wall Carbon Nanotubes (MWNTs). Motivated from possible future applications, for instance in new composite materials, the investigations of the interaction behavior of individual Carbon Nanotubes within an assembly of Carbon Nanotubes is mandatory in order to understand the behavior of larger scale structures made from CNTs, e.g. Carbon Nanotube fibers. The present research applies the Lennard‐Jones potential for modeling the van‐der‐Waals interaction occurring between the nanotubes realizing the interaction behavior. The individual Carbon Nanotubes within the assembly are assumed to be rigid. All van‐der‐Waals bonds are taken into account in order to calculate an overall potential surface describing the behavior of the investigated structure. An example consisting of a Multi Wall Carbon Nanotube made of three armchair Single Wall Carbon Nanotubes (SWNTs) is investigated (with and without additional outer force) with respect to equilibrium positions of the structure. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of material behavior via a Finite Element Model Updating strategy
Authors: Schmaltz Stefan , Willner Kai 
Published: December 2014

AbstractIn this paper an inverse and iterative method for the identification of material behavior is presented, based on the Finite Element Model Updating (FEMU) strategy. The FE simulations are performed with a commercial FE software code, using a self‐implemented elastic material model at finite strain. The iterative identification procedure is based on an experimental test (numerical) whose measured kinematic values are compared to the corresponding simulated ones. Through an optimization algorithm the material parameters are varied in a way that the least‐squares sum of the kinematic values is minimized and the optimal material parameters yielding the material behavior are identified. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computational homogenization and nonlinear effects in heterogeneous fluid saturated porous media
Authors: Rohan Eduard , Lukeš Vladimír 
Published: December 2014

AbstractFor the two‐scale modelling of deforming fluid‐saturated porous structure we apply the asymptotic homogenization approach to the fluid‐structure interaction problem involving linear elastic porous skeleton and the Newtonian compressible fluid. The sensitivity analysis of effective coefficients depending on the geometrical configuration is used to introduce a weakly nonlinear formulation which enables to capture influences of the deformation on the material properties. The paper is devoted to the comparison of the linear and the weakly nonlinear models (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermomechanical Simulation of the Electron Beam Melting Process for TiAl6V4
Authors: Riedlbauer Daniel , Mergheim Julia , Steinmann Paul 
Published: December 2014

AbstractIn the present contribution a nonlinear thermomechanical finite element model with temperature dependent material parameters is used to simulate the electron beam melting process for TiAl6V4. The beam is modeled as a moving heat source and the isentropic split solution scheme is applied. The temperature and stress distribution during the process were simulated and showed sound results from a qualitative point of view. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multi‐Scale and Multi‐Component Approach for Solidification Processes
Authors: Moj Lukas , Ricken Tim , Steinbach Ingo 
Published: December 2014

AbstractThis articel focuses on a thermo‐mechanical model for numerical simulation of solidification processes considering two different scales, both in time and space. The macro‐scale implies two phases (solid and liquid steel), and is described by use of the theory of porous media (TPM). Moreover, a strong thermal coupling is addressed as well as finite J2 elastic‐plastic solid behavior. The physics of solidification during heat dissipation is covered on the micro‐scale in the framework of phase‐field modeling. Therefore, a Ginzburg‐Landau type free energy function is used. After discussing the main model details, a numerical example will demonstrate the principal performance of the presented model. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Staggered solution of fluid‐porous‐media interaction using the method of local Lagrange multipliers
Authors: Zinatbakhsh Seyedmohammad , Ehlers Wolfgang 
Published: December 2014

AbstractSurface interaction among non‐overlapping bulk‐fluid and porous‐medium bodies occurs in different situations, e. g., the interaction of blood with a blood vessel wall, a body of water with an earth dam structure, or acoustic waves with acoustic panels used in soundproofing. These are multi‐field phenomena, comprising various surface‐ and volume‐coupling mechanisms that should be reflected in the corresponding mathematical models. These models, together with appropriate initial and boundary values, assemble a coupled problem, the solution of which reveals the behaviour of the system under external excitations. The solution is commonly done numerically, following a monolithic or a decoupled approach. Here, the focus is on the latter. To design an efficient decoupled scheme, different types of coupling within the problem are addressed. These are the volume coupling between the degrees of freedom (DOF) within each subdomain, and the surface coupling between the DOF on the common boundaries. In particular, the latter constrains the feasible space of the solution of the problem. In this regard, local Lagrange multipliers (LLM) are employed to reformulate the problem in an unconstrained form. Unlike other domain decomposition methods which are based on using global Lagrange multipliers, the LLM method yields a complete separation of the subdomains and, consequently, facilitates parallel solution of the sub‐problems. Moreover, within the subdomains, the penalty method is used to decouple pressure from other DOF. This procedure, on the one hand, reduces the size of the problem that should be solved at the interface and, on the other hand, removes the burden of using mixed finite elements within the subsystems. In the next step, the stability behaviour of the resulting staggered approach is analysed, and the unconditional stability of the method is established. Finally, the method is employed to solve a benchmark example, and using the numerical results, the reliability of the outcomes of the stability analysis is investigated. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variational formulation and finite element modelling of electrostatic‐elastodynamic coupling
Authors: Schlögl Tristan , Leyendecker Sigrid 
Published: December 2014

AbstractDielectric elastomer actuators (DEA) are composed of a series of single cells, each one equipped with two conductive layers separated by insulating dielectric silicone. As with capacitors, when an external voltage is applied to the conductive layers, an electric field is established. Due to electrostrictive effects of the silicone, the formation of dipoles leads to a contraction of the DEA. These effects are described by the Maxwell equations, the balance of momentum and constitutive material laws. Based on a model for non‐linear electroelasticity that covers the static case only, inertia terms are added in order to obtain a description of the deformation process depending on time. A potential energy function that is composed of Neo‐Hooke material behaviour, electric field energy and coupling terms covers the strong formulation. Combined with the kinetic energy, a Lagrangian forms the basis in a variational setting of the model. By applying a discrete version of Hamilton's principle, a structure preserving integration scheme for DEAs is obtained. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fluid‐structure interaction of an elastic pipe immersed in a coaxial rigid pipe: a model for the Tullio Phenomenon
Authors: Grieser Bernhard , Kleiser Leonhard , Obrist Dominik 
Published: December 2014

AbstractAn axisymmetric, elastic pipe is filled with an incompressible fluid and is immersed in a second, coaxial rigid pipe which contains the same fluid. A pressure pulse in the outer fluid annulus deforms the elastic pipe which invokes a fluid motion in the fluid core. It is the aim of this study to investigate streaming phenomena in the core which may originate from such a fluid‐structure interaction. This work presents a numerical solver for such a configuration. It was developed in the OpenFOAM software environment and is based on the Arbitrary Lagrangian Eulerian (ALE) approach for moving meshes. The solver features a monolithic integration of the one‐dimensional, coupled system between the elastic structure and the outer fluid annulus into a dynamic boundary condition for the moving surface of the fluid core. Results indicate that our configuration may serve as a mechanical model of the Tullio Phenomenon (sound‐induced vertigo). (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)