bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Prediction of Macroscopic Material Failure
Authors: Stanković Lidija , Mosler Jörn 
Published: January 2007

AbstractThe aim of this contribution is the numerical determination of macroscopic material properties based on constitutive relationships characterising the microscale. A macroscopic failure criterion is computed using a three dimensional finite element formulation. The proposed finite element model implements the Strong Discontinuity Approach (SDA) in order to include the localised, fully nonlinear kinematics associated with the failure on the microscale. This numerical application exploits further the Enhanced–Assumed–Strain (EAS) concept to decompose additively the deformation gradient into a conforming part corresponding to a smooth deformation mapping and an enhanced part reflecting the final failure kinematics of the microscale. This finite element formulation is then used for the modelling of the microscale and for the discretisation of a representative volume element (RVE). The macroscopic material behaviour results from numerical computations of the RVE. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A finite element formulation based on the Cosserat point theory
Authors: Boerner Eiris F. I. , Wriggers Peter 
Published: January 2007

AbstractThe theory of Cosserat points is the basis of a 3D finite element formulation for large deformations in structural mechanics, that recently was presented by [1]. First investigations [2] have revealed, that this formulation is free of showing undesired locking or hourglassing‐phenomena. It additionally shows excellent behaviour for any type of incompressible material, for large deformations and sensitive structures such as plates or shells. The formulation initially was restricted to a Neo‐Hookean material. This work will present the extension to a general elastic Ogden material and the verification of the chosen model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of load transfer in thermo–elastic membranes
Authors: Hornig Jörg 
Published: January 2007

AbstractThe flexural stiffness can be negligible in the analysis of extremely thin walled shell structures. Modeling these structures as membranes simplifies the theoretical formulation and reduces the computational effort. However, in case of compressive in–plane loads, the prediction of the load transition behavior by means of the membrane theory may be incorrect, if the wrinkling phenomenon is not taken into account. Therefore wrinkling algorithms were established in the past. Thermal strains influence the occurrence of wrinkling and the state of membrane forces. In order to analyze thermo‐mechanical effects in conjunction with membrane wrinkling, the Roddeman wrinkling theory was modified. For small strains the incorporation of thermal effects into the wrinkling algorithm is straight forward. A method for large strains was developed and elaborated for thermoelastic rubber–like materials. The wrinkling algorithm is easy to implement into existing FE‐programs. Results of numerical analysis are presented. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimization of Initial Deflection of a Beam‐Column (a Planar Problem)
Authors: Hýča Milan 
Published: January 2007

AbstractThe analysis present here provides formulating optimization conditions, the solution of which provides optimum variation of the initial deflection along the beam‐column eliminating internal bending moment or guaranteeing a prescribed allowable resultant deflection. Thus, a decrease in material consumption or possible increase in loading capacity may be achieved. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Four‐node Finite Element for Piezoelectric Shell Structures in Convective Co‐ordinates
Authors: Lammering Rolf , Yang Fan 
Published: January 2007

AbstractIn this contribution, an isoparametric piezoelectric shell element is presented which is based on convective coordinates and which allows for the analysis of arbitrary shell geometries. A two‐field variation formulation [1, 2] is used in which the displacements and the electric potentials serve as independent variables. Especially, for thin‐walled structures under certain boundary conditions and load cases, the displacement based element tend to shear and membrane locking. In order to avoid this poor behaviour, the Assumed Natural Strain (ANS) method [3] is introduced into the piezoelectric shell element. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Critical load of an axially compressed sandwich cylindrical panel
Authors: Laszczyk Zbigniew , Szyc Waclaw 
Published: January 2007

AbstractThe problem of critical load of an axially compressed open sandwich cylindrical shell with two straightlinear edges free is presented. Large angle of the shell sector, geometrical and physical symmetry of the facings are assumed. The simply formula for calculation critical stress in the shell is presented. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vibration of a porouse‐cellular circular plate
Authors: Magnucka‐Blandzi Ewa 
Published: January 2007

AbstractThe subject of investigation is a circular porous‐cellular plate under uniform pressure. Mechanical properties of the isotropic porous cellular metal vary accross the thickness of the plate. Middle plane of the plate is its symmetry plane. Fields of diseplacements and stresses with respect the nonlinear hypothesis are described. Basing on Hamilton principle three motion equations of the plate are formulated. These equations are approximately solved. The vibration problem is reduced to the second‐order differential equation. Numerical investigations are realised for family of plates. Natural frequencies are determined. The obtained results are shown in Figures. To the end of the investigation comparition analyses with respect to homogeneous plates is presented. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A novel h‐adaptive finite element method for standard dissipative media at finite strains based on energy minimization
Authors: Mosler J. , Ortiz M. 
Published: January 2007

AbstractA novel h‐adaptive finite element strategy for standard dissipative media at finite strains based on energy minimization is presented. The method can be applied to any (incremental) minimization problem to be analyzed by finite elements. Similarly to an error estimator by Babǔska & Rheinboldt, the proposed error indicator is based on solving a local Dirichlet‐type problem. However, in contrast to the original work, a different error indicator is considered. Provided the underlying physical problem is governed by a minimization problem, the difference between the energy of the elements defining the local problem computed from the initial finite element interpolation and that associated with the local Dirichlet‐type problem is used as an indicator. If this difference reaches a certain threshold, the elements defining the local problem are refined by applying a modified longest edge bisection according to Rivara. Since this re‐meshing strategy leads to a nested family of triangulations, the transfer of history variables necessary to describe dissipative materials is relatively inexpensive. The presented h‐adaption is only driven by energy‐minimization. As a consequence, anisotropic meshes may evolve if they are energetically favorable. The versatility and rate of convergence of the resulting approach are illustrated by means of selected numerical examples. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Frictional Contact of Rubber on rough Surfaces
Authors: Nettingsmeier Jana , Wriggers Peter 
Published: January 2007

AbstractThe aim of this work is to investigate the frictional behaviour of rubber on rough rigid surfaces. Rubber friction is composed of hysteretic and adhesional effects. The main focus lies on the hysteresis theory which motivates rubber friction with the internal damping inside the viscoelastic material.It is necessary to perform a multiscale analysis to regard the roughness of the surface on all important length scales. The fractal surface is approximated by a superposition of harmonic functions. The simulations will start at the lowest wavelength and proceed to larger scales by replacing the smaller roughness with the ascertained friction law. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bicriterion Optimization of Cold‐Formed Thin‐Walled Beams
Authors: Rodak Marcin 
Published: January 2007

AbstractBicriterion optimization of cold‐formed thin‐walled beams is presented in this paper. Simply supported beams with the crosssection similar to I‐section are considered. They are loaded with bending moments on both ends. The area of the cross section and relative maximum deflection are optimization criteria. The geometrical, strength and stability constraints are taken into account during the optimization process. The results of an example problem are presented in the form of tables. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anisotropic damage of shock wave‐loaded plates
Authors: Stoffel Marcus , Schmidt Rüdiger , Weichert Dieter 
Published: January 2007

AbstractIn the present study circular metal plates are subjected to impulsive loadings in shock tubes. The damage growth in the plate specimens until failure is predicted by finite element simulations. The aim is to validate the applied isotropic and anisotropic damage laws by means of comparisons between calculated and measured deformations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inverse Identification of Delamination Regions in Layered CFRP‐Composites
Authors: Tsotsova Rumena , Schnack Eckart 
Published: January 2007

AbstractIn this paper we are concerned with the complete non‐destructive reconstruction (shape, depth and topology) of delaminations in one damaged interface in layered composites using the Cauchy data on the outer boundary. The proposed method combines an iterative algorithm for solution of mixed ill‐posed elliptical boundary value problems and a parameter estimation in sense of the ill‐posed optimization problems. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vibrations of a Pendulum with Oscillating Support and Extra Torque
Authors: Borowiec Marek , Litak Grzegorz , Troger Hans 
Published: January 2007

AbstractThe motion of a driven planar pendulum with vertically periodically oscillating point of suspension and under the action of an additional constant torque is investigated. We study the influence of the torque strength on the transition to chaotic motions of the pendulum using Melnikov's analysis. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation and Measurements of Rolling Tire Dynamics
Authors: Brinkmeier Maik , Nackenhorst Udo 
Published: January 2007

AbstractThe simulation of rolling tires including stationary rolling, modal analysis, excitation with roughness of road surfaces and sound radiation is presented for state of the art industrial tire models. The target of this research, part of the german project “Leiser Straßenverkehr”, is the reduction of trafic noise, whereas the main source, namely the tire/road system, is investigated in contrast to other techniques like sound insulating walls.The needs and methods for the solution of the resulting large scale problems are discussed next to special properties of rotating structures, high frequency behavior of rubber material and approaches for the reduction of computational cost. For the validation of the model measurements of real tires and roads are used. These include shaker tests of the standing tire and acoustics of tires rolling on a drum. The same set–ups are applied to the simulation for the comparison of frequency response functions and sound pressure levels. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electro‐vibro‐acoustic Simulation of Linear Vibrations in Ducts
Authors: Kletschkowski Thomas , Sachau Delf , Umer Draz Rana 
Published: January 2007

AbstractDue to standing waves the creation of artificial free‐field conditions is required to detect sound sources in weakly damped interiors. Normally sound absorbing material is mounted on the interior walls to eliminate unwanted reflections. In contrast to this time consuming procedure, the present paper describes a local approach that is based on a sound intensity probe with an active free‐field (SIAF). To study the dynamical behavior of a first SIAF‐prototype that consists of two electro‐dynamical loudspeakers mounted at the ends of a duct, an electro‐vibro‐acoustical model was implemented in Matlab/Simulink, and the dynamic behavior of the system was analyzed numerically. The results of these simulations proved that a one‐dimensional free‐field can be produced successfully, if a wave‐separation approach together with an adaptive LMS‐algorithm is applied. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient Calculation of Tread Block Vibrations
Authors: Moldenhauer Patrick , Kröger Matthias 
Published: January 2007

AbstractA model is presented that allows to calculate the dynamics of tyre tread blocks. The numerical efficiency is achieved by the combination of static and important modal ansatz functions, also known as Hurty/Craig/Bampton transformation. Nonlinear single point contacts provide the contact forces and consider the surface roughness. The non‐smooth friction characteristic is approximated an arctan function and a parameter study of the slope parameter is conducted. Typical stickslip limit cycles of the tread block are shown. These phenomena can have a part in the tyre/road noise. Experimental results qualitatively agree with the modelled tread block vibrations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impedance Losses in Negative Capacitance Circuits for Semi‐Passive Vibration Control with Piezo‐Ceramics
Authors: Oleskiewicz Robert , Neubauer Marcus , Krzyzynski Tomasz 
Published: January 2007

AbstractDamping or absorbing effect in vibration control applications with piezo elements may be customized by an external impedance shunt branch connected to the plates of the piezo element. The negative capacitance present in the shunt significantly improves the damping and absorbing performance of such systems. The circuit is built up of an electronic gyrator realized by the operational amplifier, which is in reality not the ideal element. Therefore the performance of the proposed systems is limited, concerning the maximum voltages and currents at which the operational amplifiers can operate. In the paper, the finite gain of the operational amplifier, together with the loss impedances and the feedback gain factor is studied. The influence of the certain imperfections in the design of the electronic gyrator is based on 1DOF mechanical oscillator, with a piezo stack. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quietschen von KFZ‐Scheibenbremsen
Authors: Schlagner S. , von Wagner U. 
Published: January 2007

AbstractQuietschen ist ein lästiges Problem bei KFZ‐Scheibenbremsen, welches aus Selbsterregten Schwingungen resultiert. In der vorliegenden Arbeit wird der Frage nachgegangen, inwieweit der Phasenversatz zwischen Reibungskräften und in‐plane Bewegung des Bremsbelags ein Kriterium für die Quietschfreudigkeit einer Scheibenbremse sein kann. Entsprechende Ansätze ergeben sich aus theoretischen Vorüberlegungen [1] und experimentellen Untersuchungen [2]. Anhand von einfachen Modellen wird hier geklärt, ob diese beiden Größen den Anregungsmechanismus für Bremsenquietschen abbilden können. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inverse Eigenvalue Problems in Structural Dynamics
Authors: Wagner Nils 
Published: January 2007

AbstractWe consider the numerical solution of inverse eigenvalue problems (IEP). Two different formulations are used. The methods are applied to a certain mechanical system. Due to the special structure of the mass and stiffness matrix we benefit from a secular equation. The roots of that equation are the eigenvalues of the system. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the crosswind stability of high speed railway vehicles
Authors: Wetzel Christian , Proppe Carsten 
Published: January 2007

AbstractThe crosswind stability against overturning is a major national design criterium for high‐speed railway vehicles. Due to the increasing interoperability in Europe it has also become an important international task. Especially modern light‐weight trains are at risk to fail and counter‐measures as for example wind‐fences or adding extra weight in the underbelly are always very expensive. In recent years efforts were made to derive an uniform rule in certifying railway vehicles. In this case especially probabilistic methods were proposed. These probabilistic technics are common design criteria for wind turbines. This paper presents a sophisticated method to compute the reliability of railway vehicles under strong crosswind. In consideration of the given gust signal and the high‐frequency, turbulent fluctuations of the wind the response of a simplified train model is computed. The major failure criterium to determine the reliability is the lowest wheel‐rail contact force of the railway vehicle. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling and Computation of 3D Discontinuities in Solids
Authors: Jäger P. , Mergheim J. , Kuhl E. , Steinmann P. 
Published: January 2007

AbstractStrong and weak discontinuities can appear in different fields of mechanics. Some obvious examples where strong discontinuities arise are stationary and propagating cracks. This manuscript will thus discuss a geometrically nonlinear, meshindependent finite element framework for the modelling of stationary and propagating cracks in three dimensional continua. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Constitutive Model for Magnetostrictive Materials ‐ Theory and Finite Element Implementation
Authors: Linnemann Konrad , Klinkel Sven 
Published: January 2007

AbstractA 3D macroscopic constitutive law for hysteresis effects in magnetostrictive materials is presented and a finite element implementation is provided. The novel aspect of the thermodynamically consistent model is an additive decomposition of the magnetic and the strain field in a reversible and an irreversible part. Employing the irreversible magnetic field is advantageous for a finite element implementation, where the displacements and magnetic scalar potential are the nodal degrees of freedom. To consider the correlation between the irreversible magnetic field and the irreversible strains a one‐to‐one relation is assumed. The irreversible magnetic field determines as internal variable the movement of the center of a switching surface. This controls the motion of the domain walls during the magnetization process. The evolution of the internal variables is derived from the magnetic enthalpy function by the postulate of maximum dissipation, where the switching surface serves as constraint. The evolution equations are integrated using the backward Euler implicit integration scheme. The constitutive model is implemented in a 3D hexahedral element which provides an algorithmic consistent tangent stiffness matrix. A numerical example demonstrates the capability of the proposed model to reproduce the ferromagnetic hysteresis loops of a Terfenol‐D sample. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
CO2 foaming based on polystyrene/poly(methyl methacrylate) blend and nanoclay
Authors: Han Xiangmin , Shen Jiong , Huang Hanxiong , Tomasko David L. , Lee L. James 
Published: January 2007

AbstractA poly(methyl methacrylate) (PMMA) and nanoclay composite was dispersed into polystyrene (PS) using a twin‐screw extruder. The mixture was then batch foamed with supercritical CO2. It was found that the cell density of foams based on the blend is higher than that based on the weight average of the two pure polymer components at the same foaming conditions. The cell size decreases and the cell density increases with the increase of the PMMA domain size. One explanation is that the large PMMA domains serve as a CO2 reservoir and the nucleation in the PS phase is enhanced by the diffusion of CO2 from the PMMA phase to the PS phase. Very small PMMA domains cannot function as a CO2 reservoir, and so they are not able to facilitate the nucleation. A much higher cell density and smaller cell size were observed when nanoclay was located at the interface of the PMMA and the PS domains, serving as the heterogeneous nucleating agents. POLYM. ENG. SCI., 47:103–111, 2007. © 2007 Society of Plastics Engineers
Computation of starch cationization performances by twin‐screw extrusion
Authors: Berzin Françoise , Tara Ahmed , Tighzert Lan , Vergnes Bruno 
Published: January 2007

AbstractA theoretical model for the cationization of plasticized wheat starch in a modular seIf‐wiping co‐rotating twin screw extruder was developed. Our objective was to build a model which would be able to predict the evolution of the cationization reaction along the screws, in relation with the processing conditions and the geometry of the twin screw extruder. Based on previous studies on reactive extrusion modeling, the present model takes into account the interactions occurring between the flow conditions encountered in the extruder and the kinetics of the reaction. It allows one to predict the influence of operating parameters such as reagent concentrations, feed rate, screw speed, and barrel temperature on the reaction extent. Depending on conditions, degrees of substitution in the range 0.01–0.05 are obtained, with efficiencies between 30 and 90%. A good agreement is found between theoretical results and experimental measurements, allowing future use of the model for optimization and scale‐up purposes. POLYM. ENG. SCI., 47:112–119, 2007. © 2007 Society of Plastics Engineers
Processability, property, and morphology of biodegradable blends of poly(propylene carbonate) and poly(ethylene‐co‐vinyl alcohol)
Authors: Jiao J. , Wang S.J. , Xiao M. , Xu Y. , Meng Y.Z. 
Published: January 2007

AbstractBiodegradable blends of poly(propylene carbonate) (PPC) and poly(ethylene‐co‐vinyl alcohol) (EVOH) were melt compounded in a batch mixer followed by compression molding. The processability, mechanical properties, thermal behavior, and morphologies of the blends were investigated with torque rheometer, Fourier transform infrared spectroscopy, tensile tests, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. Torque rheometry indicated good interfacial miscibility between PPC and EVOH phases, and then fourier transform infrared spectroscopy spectra demonstrated that a certain extent of hydrogen‐bonding interactions between PPC and EVOH matrix in the blends. A study of the mechanical properties and thermal behavior showed that the EVOH incorporation can significantly enhance the tensile strength, thermal stability, and crystallinity of the blends. Moreover, dynamic mechanical analysis and differential scanning calorimetry both revealed that PPC and EVOH were compatible to some extent. Further, scanning electron microscopic examination also revealed the good interfacial adhesion between EVOH and PPC phases. POLYM. ENG. SCI., 47:174–180, 2007. © 2007 Society of Plastics Engineers