bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crack propagation for the material force approach using adaptive meshing
Authors: Qinami Aurel , Kaliske Michael 
Published: October 2016

AbstractIn this publication, a contribution of the material force approach in Linear Elastic Fracture Mechanics (LEFM) is studied. The fracture criterion and crack propagation direction are depicted using material force which follow the Griffith theory. The implementation of this criterion is based on a purely thermodynamic description. Discrete modelling of crack propagation, apart of its mechanics, requires special techniques for manipulation of the finite element mesh for a given structure. The well known node splitting algorithm can be implemented and combined with r‐ or h‐adaptive approaches. The former one consists in moving specific nodes in the direction of a crack path. This method is easier to handle but it suffers from the degradation of finite elements. The latter one is more effective when an external remeshing process for a certain area around crack tip is used. This increases the computation cost, but on the other hand, it improves accuracy of results. For both models, an effective data structure needs to be created which has to be generated after each adaptation of the mesh configuration. This significantly increases the computation time. These methods allow realistic modelling of the crack path according to the crack driving force direction. In this work, both methods are considered separately and combined for two‐ and three‐dimensional simple geometry specimens where linear elastic material behavior is taken into account. These methods are tested for tension specimens in mode I and mixed mode. A three‐dimensional torsion simulation is investigated as well. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PC expansion for material parameters using artificial data and statistical methods
Authors: Caylak Ismail , Nörenberg Nicole , Mahnken Rolf 
Published: October 2016

AbstractThis paper investigates the uncertainty of a hyper‐elastic model by random material parameters as stochastic variables. For its stochastic discretization a polynomial chaos (PC) is used to expand the coefficients into deterministic and stochastic parts. Then, from experimental data in combination with artificial data for elastomers the distribution of the force‐displacement curves are known. In the numerical example the PC‐based stochastic and the deterministic parameter identification are used for generation of the distribution of Ogden's material parameters. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Patch coupling with the isogeometric dual mortar approach
Authors: Dornisch Wolfgang , Müller Ralf 
Published: October 2016

AbstractThe use of a common set of basis functions for design and analysis is the main paradigm of isogeometric analysis. The characteristics of the commonly used non‐uniform rational B‐splines (NURBS) surfaces require methods to handle non‐conforming meshes to attain an efficient computational framework. The isogeometric mortar method uses constrained approximation spaces to enforce a coupling of deformations at the interface between patches in a weak manner. This method neither requires additional degrees of freedom nor the choice of empirical parameters. The main drawback of the standard isogeometric mortar approach is the non‐local support of the mortar basis functions along the interface. This yields a large number of nodes per element for elements adjacent to the interface. Thus, the computational costs increase significantly for mesh refinement. This issue is remedied by the use of dual basis functions for the mortar method, which is referred to as dual mortar method. In this contribution several choices for the dual basis functions for B‐splines are proposed and compared. A special focus is set on the support of the dual basis functions and on the support of the resulting mortar basis functions. Numerical examples show the influence of the choice for the dual basis functions on the accuracy of the global stress distribution, on the fulfillment of the interface conditions and on numerical efficiency. The use of approximate dual basis functions is shown to be competitive to computations of conforming meshes in terms of accuracy and efficiency. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Specimen design for high precision tension‐compression tests
Authors: Kanzenbach Lars , Naumann Christoph , Ihlemann Jörn 
Published: October 2016

AbstractIn this contribution a new specimen, which enables high precision tension‐compression testing, is presented. Due to a special mounting geometry, tests from a compression strain of −45 % up to a tension strain of 400 % can be performed with a nearly homogeneous deformation field within the measuring zone. Consequently, the mechanical behavior of rubber, which exhibits phenomena like Mullins effect, Payne effect, recovery and relaxation behavior, can be characterized within experimental investigations. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure analysis of higher‐order variational integrators and implementation of SUNDMAN adaptivity in time
Authors: Masser Robin , Bartelt Matthias , Groß Michael 
Published: October 2016

AbstractIn this paper, we investigate the use of different higher‐order polynomial bases for the temporal approximation as well as various higher‐order quadrature rules. The resulting time integration schemes partially differ in their numerical properties, especially in order convergence and energy error. Further, an adaptivity of the time increment to optimize the computational effort is implemented using a time transformation according to SUNDMAN. Using an example with viscoelastic material behavior that models a bungee jumper, we show its advantages to minimize the energy error. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interface finite elements within a three dimensional frictional contact formulation
Authors: Michaloudis Georgios , Konyukhov Alexander , Gebbeken Norbert 
Published: October 2016

AbstractThis contribution presents a finite element appropriate for the modeling of general interfaces, incorporating normal contact conditions as well as description of the tangential interaction on the interface. The finite element is formulated as a solid element and its kinematics take into account the kinematics of both Master and Slave. A covariant approach is adopted for the exact representation of the geometry of the interface and all parameters are expressed in terms of local coordinate systems. An elastoplastic associative constitutive law assuming plastic deformations, which is numerically implemented as a frictional law describes the tangential interaction of the contact surfaces. In this way a three‐dimensional Segment‐to‐Segment frictional contact formulation, applying an associative plasticity law instead of the Coulomb friction law is presented. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solving the linear inhomogeneous differential equation in the simulation model of passenger car tire
Authors: Sarkisov Pavel , Prokop Günther , Wensch Jörg 
Published: October 2016

AbstractThe paper represents an analysis of different approaches to solve a specific practical task – to find a solution of the inhomogeneous differential equation, which describes tire lateral deformation by means of the beam theory. The equation has fourth order and is linear, the inhomogeneneous part is discrete nonmonotone function. The options to substitute this function with polynomial, linear segments or Fourier series are compared concerning solution error and computation time. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A‐priori error estimates for consistent, refined theories for thin structures
Authors: Schneider Patrick , Kienzler Reinhold 
Published: October 2016

AbstractWe propose an extension of the uniform approximation approach towards the simultaneous truncation of the associated dual energy. In the talk, we derive a hierarchy of approximating theories and corresponding a‐priori error estimates for their solutions, for the special case of an isotropic, linear elastic, one‐dimensional structural member with rectangular cross‐section. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical analysis of reinforced concrete structures with particular focus on bond behaviour
Authors: Stein Timo , Kowalsky Ursula , Dinkler Dieter 
Published: October 2016

AbstractA non‐linear bond model is presented, capturing bond behaviour between concrete and reinforcing ribbed steel bars. An existing model, where coupled thermal‐hygric‐mechanical‐chemical (THMC‐) processes are already modelled for pure concrete, will be extended by the presented bond model. Against this background and due to the resulting requirements the approach of a geometrically consistent consideration of the reinforcement is chosen, neglecting the bar ribs in the geometric model. All bond mechanisms are considered by the additional bond model in between concrete and reinforcement. With this procedure the principle of a formal treatment and general description, used in the existing model describing the different processes, is not only continued, but also transferred regarding the three components concrete, steel and bond. The bond model is discretized by interface elements, which describe curved surfaces in 3D space. The presented non‐linear bond model incorporates the mechanical interaction of the bar rips with adjacent concrete as well as the damage of the bond zone. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Notes on a novel finite element for anisotropy at large strains
Authors: Viebahn Nils , Schröder Jörg , Wriggers Peter , Balzani Daniel 
Published: October 2016

AbstractA locking phenomenon can be observed in the case of anisotropic elasticity, due to high stiffness in preferred directions. In this contribution we propose a formulation with the goal to overcome this locking problem. We apply a Simplified Kinematic for the Anisotropic part of the free‐energy by means of a constant approximation of the right Cauchy‐Green tensor. For the tested boundary value problem the SKA‐element performs excellent and behaves extremely robust. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the piezotronics and tactile sensing virtual simulation
Authors: Chiroiu Veturia 
Published: October 2016

AbstractA flexible finger with muscles made of Nitinol wires and the skin made of auxetic material is analyzed from the tactile sensing point of view. The recognizing of the shape and texture of 3D objects is performed by simulation the action of an array of nanopiezotronic transistors integrated into the skin. The array of nanopiezotronic transistors makes possible the detection of the pressure‐induced changes in the auxetic skin. The shape and texture of the objects is best estimated by determining the surface and texture as an n‐ellipsoid defined by 12 parameters. An inverse problem is solved in order to find these parameters from the condition that the n‐ellipsoid best fits the set of data points probed by touch with the finger. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Asymptotic behavior of solutions of nonlinear systems with multiple imaginary eigenvalues
Authors: Grushkovskaya Victoria 
Published: October 2016

AbstractThe paper is devoted to the analysis of the decay rate of solutions of a nonlinear system with two pairs of purely imaginary eigenvalues. The main result is the power estimate for the norm of solutions. It is proven that the order of such estimate varies for cases of a diagonalizable matrix of linear approximation, and for a matrix containing a Jordan block. Another result of this work provides sufficient asymptotic stability conditions regardless of forms higher than the third order. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Pin‐on‐Disk Experimental Set‐up for Vibrational Smoothing of Dry Friction
Authors: Kapelke Simon , Seemann Wolfgang 
Published: October 2016

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. Recent contributions have discussed the influence of contact compliance on vibrational smoothing. Within this contribution, an experimental set‐up is presented, which has been developed in order to validate the calculated results. After a brief description, some general properties of the system are investigated, including stationary and oscillatory behaviour. Without vibrational excitation, friction induced vibrations occur at low sliding velocities. The corresponding motion of the system is analysed and compared to the results of FE‐based simulations. Finally, a first attempt is presented reducing the average friction force by imposing appropriate vibrations. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synchronization effects in rotors partially filled with fluid‐influence on propulsion
Authors: Keisenberg Tobias , Ostermeyer Georg‐Peter 
Published: October 2016

AbstractIn fluid‐filled Rotors occur self‐excited vibrations induced by surface waves of the fluid. A characteristic property is the instability over an interval of angular velocity above the natural frequency of the system. One explanation is the occurrence of synchronization effects between fluid waves and the critical rotor speed.The behaviour of rotors partly filled with fluid was mostly studied under the aspect of stability in steady‐state conditions. For non‐steady‐state investigations, discrete models with reduced number of degrees of freedom and reasonable ability to model the system behaviour are desirable for observer‐based real‐time control.This paper analyses a model based on a laval rotor and shows synchronization effects between fluid waves and rotor model and its influence on the rotor propulsion. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vibrations of Rotors Supported on Nonlinear Bearings
Authors: Mair Mathias , Haas Stefan , Ellermann Katrin 
Published: October 2016

AbstractRotors in electrical machines are supported by various types of bearings. In general, the rotor bearings have nonlinear stiffness properties and they influence the rotor vibrations significantly. In this work, this influence of these nonlinearities is investigated. A simplified finite element model using Timoshenko beam elements is set up for the heterogeneous structure of the rotor. A transversally isotropic material model is adopted for the rotor core stack. Imposing the nonlinear bearing stiffnesses on the model, the Newton‐Raphson procedure is used to carry out a run up simulation. The spectral content of these results shows nonlinear effects due to the bearings. The rotor vibrations are further investigated in detail for various constant speeds. These results show non‐harmonic vibrations of the rotor in a section of the investigated speed range. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the refined modeling of the force distribution in a bistable magnetoelastic energy harvesting system due to a magnetic field
Authors: Noll Max‐Uwe , Lentz Lukas 
Published: October 2016

AbstractAbstract: The problem of a bistable magnetoelastic beam under base excitation was discussed in [1] under the aspect of chaotic behaviour in mechanical systems. Three decades later the system was used in [2] to design an energy harvesting system which performs well under harmonic excitation for a broad range of excitation frequencies due to its bistability. The initial modeling was tailored to obtain a model with one degree of freedom based on the assumption that the magnetic force acts on the beam tip only. A more appropriate model can be found when considering a distributed force along the beam.The authors present the force distribution on a ferromagnetic beam due to the magnetic field of two permanent magnets. A semi‐analytic method is used to compute the magnetic field. The force distribution can in future be used to derive a refined nonlinear dynamical model for the ferromagnetic elastic beam. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hopf‐Takens‐Bogdanov interaction for a fluid‐conveying tube
Authors: Steindl Alois 
Published: October 2016

AbstractWe investigate the dynamics after loss of stability of the downhanging configuration of a fluid conveying tube with a small end mass and an elastic support.By varying the fluid flow rate and the stiffness and location of the elastic support, different degenerate bifurcation scenarios can be observed. In this article we investigate the bifurcating solution branches of the codimension 3 interaction between a Hopf bifurcation and a Bogdanov‐Takens bifurcation.A complete discussion of the primary and secondary solution branches was already given by W. F. Langford and K. Zhan. After reducing the system to the three‐dimensional Normal Form equations we apply a numerical continuation procedure to locate the expected higher order bifurcation branches and detect more complicated dynamics, like Shilnikov orbits. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental and theoretical investigation of creep groan of brakes through minimal models
Authors: Zhao Xingwei , Gräbner Nils , von Wagner Utz 
Published: October 2016

AbstractCreep groan of brake systems is a low frequency vibration phenomenon occurring at low speeds which can make passengers feel uncomfortable. This phenomenon is caused by the stick‐slip‐effect resulting in limit cycle oscillations with frequencies lower than 200 Hz. For the experimental investigation of this problem, an idealized brake test rig is designed concentrating on the investigation of the frictional contact by realizing low damping and small disturbances in the system. Different sensors are utilized in the test rig. Limit cycles and bifurcation effects can be observed in the experimental results. With respect to modeling, a one degree‐of‐freedom (DOF) model using Coulomb's friction law and a two DOF model using the bristle friction law are considered. In a comparative study of experimental and simulation results, the parameters of both friction laws can be identified from the dynamic experimental results, such as the static and dynamic friction coefficients, contact stiffness and Stribeck velocity. Experimental and theoretical results show a very good concordance. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A coupled finite element approach for the modelling of composites with fibres possessing fibre‐bending stiffness
Authors: Asmanoglo Tobias , Menzel Andreas 
Published: October 2016

AbstractThe algorithmic implementation of a constitutive model for fibre‐reinforced materials with fibre‐bending stiffness, in addition to the classical directional contributions of the fibres, is presented. Based on theoretical investigations presented in [1], the numerical solution of the underlying non‐linear system of coupled partial differential equations by means of a mixed‐type multi‐field finite element approach is discussed. To this end, additional field variables are introduced to approximate higher‐order gradients which enter the proposed energy function of the extended continuum and, accordingly, introduce a size effect into the model. Concluding, representative boundary value problems are solved to analyse the basic properties of the model. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
DEM‐FEM coupled numerical investigation of granular materials to increase crashworthiness of double‐hull vessels
Authors: Chaudry Mohsin Ali , Woitzik Christian , Weißenfels Christian , Düster Alexander , Wriggers Peter 
Published: October 2016

AbstractIn this contribution, a novel design strategy is investigated for improving the crashworthiness of double‐hull vessels, which involves usage of granular materials. For numerical simulation, a framework based on coupling of the Discrete Element and the Finite Element Method is used to study load bearing capacity of granular materials during uniaxial compression. In addition, the effect of Young's modulus of particles is also investigated with respect to the load transferability. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of hydrodynamic strain amplification in filled elastomers
Authors: Darabi Ehsan , Itskov Mikhail , Klüppel Manfred 
Published: October 2016

AbstractPolymer chains in filled elastomers are subject to a strain bigger than the overall (macro‐strain) applied to the specimen, which is described by a strain amplification factor. In the current paper, a micromechanical model for hydrodynamic strain amplification is presented. To this end, we develop the concept of the multiple filler fractions within the so‐called Dynamic Flocculation Model (DFM) framework. Accordingly, with increasing strain, a single unbroken virgin cluster gradually splits into smaller clusters. Thus, fractions of smaller filler clusters increase with the increasing strain, which in turn influences the filler‐induced hysteresis. The filler induced hysteresis is then described by the cyclic breakdown of the residual fragile filler clusters and re‐aggregation of the already broken filler‐filler bonds. The model includes a few number of physically motivated material constants describing the average filler cluster dimensions, filler‐filler and filler‐matrix interaction properties. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A thermodynamic framework for coupled multiphase field and diffusion models for lower bainite transformation
Authors: Düsing Martin , Mahnken Rolf 
Published: October 2016

AbstractThe lower bainite transformation is characterized by a displacive transformation from austenite to bainitic ferrite and a subsequent separation of carbon within the new supersaturated phase. At accumulations of carbon carbides precipitate. To model this complex process a framework considering phase changes and carbon diffusion is required. In this work we present a thermodynamic framework based on the theory of microforce balances considering multiphase Ginzburg‐Landau equations coupled with Cahn‐Hilliard diffusion. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crysal Plasticity Finite Element Simulations based on Continuum Dislocation Dynamics
Authors: Ebrahimi Alireza , Hochrainer Thomas 
Published: October 2016

AbstractPlastic deformation of crystalline materials is the result of the motion and interaction of dislocations. Continuum dislocation dynamics (CDD) defines flux‐type evolution equations of dislocation variables which can capture the kinematics of moving curved dislocations. Coupled with Orowan's law, which connects the plastic shear rate to the dislocation flux, CDD defines a dislocation density based material law for crystal plasticity.In the current work we provide simulations of a micro‐bending experiment of a single crystal and compare the results qualitatively to those from discrete dislocation simulations from the literature. We show that CDD reproduces salient features from discrete dislocation simulations regarding the stress distribution, the dislocation density and the accumulated plastic shear, which would be hard to obtain from more traditional crystal plasticity constitutive laws. © 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)