bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two DOF model with friction to simulate rope climbing accident
Authors: Tatzko Sebastian 
Published: November 2010

AbstractA two degree of freedom model is considered consisting of an elastic rope with a point mass on each end. The rope is hanging over a fixed drum and the contact is modeled frictional. The Eytelwein formula for rope friction can not directly be solved for the rope forces, because of the elasticity of the rope. An extended way to calculate the rope forces will be shown and used to solve the equations of motion for the system. Some numerical results show the motion of the two masses. The considered mechanical system was used to simulate a lead climbing accident. In the case of lead climbing one end of the rope is tied rigidly to the climber then goes through a carabiner that is fixed in the wall and runs down to a second person called the belayer. The elasticity of the rope makes sure that the forces acting on the climber stay low and avoid a sudden stop. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Deep Drawing Simulations Based on Microstructural Data
Authors: Phan Van Tung , Jöchen Katja , Melcher Andreas , Böhlke Thomas 
Published: November 2010

AbstractFor the optimization of process chains in sheet metal forming it is required to accurately describe each partial process of the chain, e.g. rolling, press hardening and deep drawing. The prediction of the thickness distribution and the residual stresses in the blank has to be of high reliability, since the subsequent behavior of the semi‐finished product in the following subprocesses strongly depends on the process history. Therefore, high‐quality simulations have to be carried out which incorporate real microstructural data [1,2,3]. In this contribution, the ferritic steel DC04 is analyzed. A finite strain crystal plasticity model is used, for the application of which micro pillar compression tests were carried out experimentally and numerically to identify the material parameters of DC04. For the validation of the model, a two‐dimensional EBSD data set has been discretized by finite elements and subjected to homogeneous displacement boundary conditions describing a large strain uniaxial tensile test. The results have been compared to experimental measurements of the specimen after the tensile test. Furthermore, a deep drawing process is simulated, which is based on a two‐scale Taylor‐type model at the integration points of the finite elements. At each integration point, the initial texture data given by the aforementioned EBSD measurements is assigned to the model. By applying this method, we predict the earing profiles of differently textured sheet metals. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Calibration of a polychromatic CT equipment for biological tissue samples enriched with magnetic nanoparticles.
Authors: Rahn Helene , Odenbach Stefan 
Published: November 2010

AbstractMicro‐computed tomography (µCT) is a widely used imaging technique. Tomography has been used to study the distribution of magnetic nanoparticles within cancerous tissue after minimal‐invasive cancer treatments such as magnetic drug targeting and magnetic hyperthermia. But not only the distribution is a relevant factor for the sucess of these therapeutic aproaches. The concentration of the magnetic nanoparticles within the respective tissue is also of great impact. In this paper we present a calibration procedure of a µCT‐equipment for biological tissue samples enriched with magnetic nanoparticles developed to enable a semi‐quantitative evaluation of 3‐dimensional data sets. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new modelling approach for the description of tissues at cell level
Authors: Seydewitz Robert , Böl Markus 
Published: November 2010

AbstractThe understanding of tissues from a biomechanical perspective requires a deeper knowledge about cell mechanics. A lot of experimental and theoretical investigation has already been done to consider cells' behaviour under various conditions. Several types of cells exist, each with specific properties. In this work, the cell microstructure is characterized and explained via tensegrity systems. In doing so, we consider in a first step a simple cubic shaped cell built up by trusses and ropes that are discretized by finite 1D elements. This simplified microstructure represents the micro/cell level on the integration point of the finite element discretization at macro level. By using an appropriate homogenization technique for the micro level, it is assumed to gain a more detailed view on deformations occur on cell level. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Continuum‐Mechanical Analysis of Human Brain Tissue
Authors: Wagner Arndt , Ehlers Wolfgang 
Published: November 2010

AbstractThe effective treatment of brain diseases, such as malignant brain tumours, is generally constricted by the controlled contribution of therapeutic agents. Novel brain tumour therapy proceeds from a direct infusion of the drug into the extra‐vascular space of the nervous brain tissue (convection‐enhanced delivery). This is carried out using catheter to bypass the blood‐brain barrier, which effectively separates brain tissue from the intra‐vascular space and hence hamper drug delivery through the bloodstream. The dilation of the target tissue, as response to the local pressure increase, initiates interstitial fluid flow and, thus, the distribution of the chemical agents. An adequate constitutive model of the complex tissue aggregate in the framework of the Theory of Porous Media is essential in order to assist modern clinical application via numerical simulations. The presented model consists of an elastically deformable solid skeleton, provided by the tissue cells, permeated by two viscous, materially incompressible pore‐liquid phases, interstitial fluid and blood plasma. Both liquids are mobile within the solid skeleton and separated from each other. With regard to simulate a drug infusion process in the extra‐vascular space, the interstitial fluid is treated as a solution of a liquid solvent and a dissolved therapeutic solute. The constitutive assumptions for the involved constituents are adjusted in order to describe the physical behaviour of human brain tissue. The presented numerical examples illustrate the fundamental effects during an infusion process. Therefore, the resulting set of coupled partial differential equations is spatially discretised using hexahedral mixed finite elements with an implicit (backward) Euler time integration scheme to solve the considered problem in a monolithic manner for the primary variables. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Simulation of Spot‐Weld Joints under Crash Loading
Authors: Basaran Merdan , Wölkerling Sven David , Feucht Markus , Weichert Dieter 
Published: November 2010

AbstractThis paper compares FE simulations of spot‐weld joints for dual‐phase steel under different load cases by using damage models of Gurson‐Tvergaard‐Needleman (GTN) and its two extensions, GTN‐Johnson‐Cook and GTN‐Hutchinson. Spot‐weld specimens have three zones depending with different material properties: Base material, heat‐affected zone and fusion zone. The characterization of the base material is straightforward. The other two zones are characterized with specifically heat‐treated specimens. For each zone, flat smooth tensile, flat notched tensile and Iosipescu‐shear specimen are used in order to obtain the damage behavior for different triaxiality values. GTN damage model parameters are calibrated with the help of smooth and notched flat tensile specimens. The parameters of the above mentioned extensions of GTN damage model are identified with the help of Iosipescu‐shear specimen. Finally, the calibrated material models are used in the FE simulation of the spot‐weld specimens under quasi static‐load case (10 mm/min) for loading directions of 0°, 30°, 60°, 90°. The numerical force‐displacement results are in good agreement with experimental results. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of Experimental Methods for Interface Problems Based on Virtual Testing
Authors: Brylka Barthel , Fritzen Felix , Böhlke Thomas , Weidenmann Kay 
Published: November 2010

AbstractThe effective properties of fiber reinforced materials depend strongly on the properties of the interface between the phases. In the particular case of glass fiber reinforced thermoplastics, this bonding is inherently weak and needs to be improved, e.g., by addition of compatibilyzers. Reliable experimental setups are needed in order to investigate the effects of such additives on the interface properties. In this contribution, the sensitivity of push out experiments with respect to the microstructure and test setup are examined in order to find such an experimental configuration. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling and numerical simulations of rate and temperature‐dependent damage and fracture in aluminum alloys
Authors: Gerke Steffen , Brünig Michael 
Published: November 2010

AbstractThe paper deals with a continuum damage model and corresponding numerical simulations of the inelastic deformation and failure behavior of aluminum alloys. The focus is on generalized plasticity, damage and fracture approaches taking into account different tiaxialities as well as rate and temperature‐dependence. Furthermore, the special intent of the present work are dynamic applications. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exponential Finite Elements for a Phase Field Fracture Model
Authors: Kuhn Charlotte , Müller Ralf 
Published: November 2010

AbstractSharp interface material models can be related to phase field models by introducing an order parameter, whose value is assigned to the different phases of a material. The elastic material law is coupled to the evolution equation of the order parameter and cracking is addressed as a phase transition problem instead of a moving boundary value problem. A regularization parameter ϵ controls the width of the diffuse cracks represented by the order parameter and the underlying sharp interface model can be recovered from the phase field model by the limit ϵ → 0. However, in numerical simulations using standard finite elements with linear shape functions, the minimum value of ϵ is restricted by the grid size and therefore the discretization of the crack field requires extensive mesh refinement for small values of ϵ. In this work, we construct special 2d shape functions which take into account the exponential character of the crack field and its dependence on the parameter ϵ. Especially in simulations with small values of ϵ and a rather coarse mesh, the elements with exponential shape functions perform significantly better than standard linear elements. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Contact Problems for Interface Cracks under Harmonic Loading
Authors: Menshykov Oleksandr V. , Menshykova Maryna V. , Guz Igor A. , Mikucka Vita A. 
Published: November 2010

AbstractThe linear crack located at the bimaterial interface between dissimilar homogeneous linearly elastic materials under normally incident harmonic tension‐compression wave is considered in the study. The problem is solved by the method of boundary integral equations using an iterative algorithm. The dynamic stress intensity factors are computed as functions of the loading frequency taking the contact interaction of the opposite crack's faces into account. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Deformation and Damaging of Composites with Transversally‐isotropic Components under Compressive Loading
Authors: Nazarenko Lidija , Khoroshun Leonid , Müller Wolfgang H. , Wille Ralf 
Published: November 2010

AbstractIn the present paper, the problem of deformation and damage of composites with a porous isotropic matrix and transversally‐isotropic unidirectional fibers under compressive loading is considered when microdamages are accumulated in the fiber. Fractured micro‐volumes are modelled by a system of randomly distributed quasi spherical pores. The Shleicher‐Nadai fracture criterion is used as a condition for the origin of micro‐pores (micro‐damage) based on the assumption of a rigid material. The limit value of the strength of the material is assumed as a stochastic function of coordinates. By using a numerical procedure, the solution of the above problem is found. The nonlinear stress‐strain diagrams for a transversally‐isotropic composite are obtained for the case of uniaxial compression‐tension along the fibers. The nonlinearity of the deformations of the composite is caused by accumulation of micro‐damages in the matrix. The influence of the physical‐mechanical properties of materials, of the volume concentration, of the porosity of components, of the geometrical parameters of the structure, and of the character of the scatter of the strength in the material on the micro‐damage of the material and, as a consequence, the influence on the macro‐stress‐macro‐strain diagram is analyzed. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Tire Model for Individual Car Indoor Noise Simulation
Authors: Chiarello Raffaela , Nackenhorst Udo 
Published: November 2010

AbstractAim of this project is to provide a physical motivated tire model in state space description for the car indoor noise simulation. The basis is a very detailed and validated finite element model of a reference tire, originally developed for outdoor noise radiation simulation, [1]. This contribution focuses on the structure born noise pathway in the frequency domain up to 200 Hz. The modeling approach is based on the assumption that a broad class of passenger car tires can be fitted with one finite element model, because the structural modes appear in principle identical in this frequency range. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Topology optimization based on the finite cell method
Authors: Düster Alexander , Parvizian Jamshid , Rank Ernst 
Published: November 2010

AbstractWe present an extension of the Finite Cell Method (FCM) to topology optimization utilizing the Fully Stressed Design (FSD) approach. The proposed method is briefly explained in 2D and its potential is demonstrated by means of a linear elastic 3D problem. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Correlation of constraint conditions in Koiter's initial postbuckling analysis and in the consistently linearized eigenvalue problem
Authors: Höfinger Gerhard , Jia Xin , Mang Herbert A. 
Published: November 2010

AbstractKoiter's postbuckling analysis and the consistently linearized eigenvalue problem are used in sensitivity analysis of the postbuckling behavior of elastic structures. A classification of structures can be made on basis of the eigenvector of the eigenvalue problem. This classification distinguishes between structures with different quality of conversion from imperfections sensitivity into imperfection insensitivity, which is expressed in terms of the coefficients of Koiter's initial postbuckling analysis. Mathematically, this connection is expressed in the correlation of constraint equations. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the consistent discretization in time of nonlinear thermo‐elastodynamics
Authors: Krüger Melanie , Groß Michael , Betsch Peter 
Published: November 2010

AbstractThe main goal of the present work is to describe two structure‐preserving time integrators, which have been proposed by Romero [1] (Thermodynamically Consistent (TC) algorithm) and Groß [2] (enhanced hybrid Galerkin (ehG) method) and to compare them with standard integrators. The numerical results of the two schemes are compared in the context of a thermoelastic two‐dimensional double pendulum. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On a concept to avoid electromechanical locking in a piezoelectric finite beam element
Authors: Legner Dieter , Wackerfuß Jens , Klinkel Sven , Wagner Werner 
Published: November 2010

AbstractWithin the development process of piezoelectric sensor and actuator applications, numerical tools are essential. These tools solve approximately the electromechanical boundary value problems received from physical descriptions. Since many piezoelectric components are generally thin rod like structures, a piezoelectric finite beam element is presented in this contribution which can be used effectively to analyze a wide range of piezoelectric devices. The mechanical strains and the electric field are coupled by the constitutive relations. This results in incompatibilities within the numerical approximations in case of bending dominated problems, which can be compared to those causing the well‐known shear locking in purely mechanical problems. This effect occurs in standard finite element formulations, where the mechanical and electrical degrees of freedom are derived from standard kinematic assumptions. The present element formulation is based on the classical Timoshenko beam theory, extended by a piezoelectric part. Each finite element node contains eight degrees of freedom: three displacements, three rotations and the electrical potential on the top and the bottom of the beam. The related fields are interpolated with linear approximation functions. In order to overcome the described problem of incompatible approximation spaces, a mixed multi‐field variational approach is introduced, wherein six independent fields are considered. These are the displacements, strains, stresses, electric potential, electric field and the dielectric displacements. It allows for 3D constitutive equations and approximations of the strains and the electric field independent of the linear interpolation functions. Throughout the beam's cross section, a set of special polynomial approaches for strains and electric field components is proposed. This leads to well‐balanced approximation functions regarding coupling of electrical and mechanical fields. Thus, electromechanical locking does not occur as is demonstrated by means of several numerical examples. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linear and nonlinear response of pipeline suspension bridge due to moving fluid
Authors: Prokopowicz Dawid , Bryja Danuta 
Published: November 2010

AbstractBasing on the nonlinear dynamic model of flexible pipeline suspended by spatial system of cables, described in Ref. [1], the linear and nonlinear vibrations are investigated in order to estimate the nonlinear effects. The model is based on substructure technique and formulated including features specific to analyzed structure, for example large displacements and time dependent parameters appearing in equations of motion due to fluid flowing inside the pipeline. Due to the fact that modelling problem for the analyzed structure is one's own complicated, a simple case when the conveying fluid is idealized simply as a ballast moving inside the pipe is considered. This paper presents a short numerical analysis of linear and nonlinear, static and dynamic response of exemplary structure for three different cases: during filling the pipe with fluid, when the pipeline is completely filled and during emptying the pipe. Moreover, for the linear problem, the influence of a speed of the fluid on the stability of the pipeline suspension bridge is investigated. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Verification of an anisotropic Coulomb adhesion‐friction law for contact surfaces with periodic structure
Authors: Schmied Christoph , Konyukhov Alexander , Schweizerhof Karl 
Published: November 2010

AbstractSliding friction forces and so‐called adhesion forces are the main mechanical characteristics to describe contact interaction. Both together are representing 2D surface constitutive laws in analogy to e.g. elasto‐plasticity for 3D continua. The classical model to generalize the Coulomb friction law into anisotropic domains is to introduce an anisotropic friction tensor. Michalowski and Mroz in [1] proposed the structure of the friction tensor considering the sliding of a rigid block on an inclined surface. Zmitrowicz in [2] developed the theoretical basis for the structure of the friction tensor on symmetry groups for the tensor. The current contribution is aimed at verification of this modeling process based on a homogenization procedure for a very fine discretization representing the exact structure of the surface. The validation issue with realistic experiments given in [4] is discussed as well. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Limit States in Alternately Loaded Plates
Authors: Todres Russell , Stoffel Marcus , Weichert Dieter 
Published: November 2010

AbstractIn the present study, a circular plate is inelastically deformed by uniform pressure, which is released and then alternately applied to the same peak level. For each iteration, snap‐through occurs at an increased pressure relative to the previous one, leading to additional inelastic deformation. At some point, either the plate fails or a limit state of deformation is reached under peak pressure without snap‐through. This phenomenon is studied experimentally and theoretically to determine the conditions under which the limit state is stable. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An improved Interior‐Point Algorithm for Large‐Scale Shakedown Analysis
Authors: Simon Jaan‐Willem , Weichert Dieter 
Published: November 2010

AbstractThis work focuses on the calculation of shakedown load‐factors of structures by using the lower‐bound theorem of shakedown analysis. The resultant optimization problem is solved by an interior‐point algorithm.In general, the application of shakedown analysis to practical problems leads to large‐scale problems with large numbers of unknowns and constraints. Thus the solution turns out to be computationally intensive. For this reason it is important to reduce the dimension of the considered problem. Therefore, the major improvement of the presented algorithm consists of a problem‐oriented reformulation of the problem reducing the size of the system to be solved. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Higher Frequency of Free Vibrations of Thin Annular Plates Made of Functionally Graded Material
Authors: Wirowski Artur 
Published: November 2010

AbstractSubject of this paper is a thin plate with a characteristic geometry: periodic in one direction and smoothly varying along the other. The aim of the contribution is to formulate and apply the averaged model which can describe higher frequencies of free vibrations. Problem of finding frequencies of free vibrations is very important. It could be applied to many engineering problems such as resonance phenomena, wave propagation, absorption of vibrations and many others. When the considered plate is made of an isotropic material, we can find the first, the second and the others frequencies in simply way. But if we consider plate made of a functionally graded material [1], which have varying properties and which is made of two components, this problem is more complicated. In this cause, apart from family of the base frequencies (first, second, etc), which depend on macroscopic properties of the plate, we have the higher frequency, which depends on a microscopic structure. We can find many papers describing the base frequencies of free vibrations for many different types of structures (for example [2] for considered type of plate). In this paper, we find the higher frequency. For solving this problem, we use the tolerance averaging technique described in [3]. This theory allows to take into account the microstructure size and to find the higher frequency of free vibrations. The equations have smooth coefficients. They can be solved numerically with help of the finite difference method, in polar coordinates for an annular plate. Next, we use special procedure for selecting of the higher frequencies of free vibrations, which depend on the microstructure size, from the list of all frequencies. After that we analyze an influence of ratios of material properties and the microstructure size on the higher frequency of free vibrations. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)