bluuebunny/crossref_metadata_2025_split huggingface dataset:
Repair of Laminates by External Patches — Analysis and Optimisation
Authors: Engels Heiko , Becker Wilfried 
Published: June 2004

AbstractThe present contribution considers the patch repair of a damaged laminate where the damaged laminate material has been removed by cutting or drilling a hole. The respective analytical assessment of such a repair configuration can be performed by the complex potential method. In order to determine the optimal repair design the present work also addresses the well‐approved techniques of mathematical structural optimisation.
Modeling of a Constrained Porous Material with an Inclusion
Authors: Giovine Pasquale 
Published: June 2004

AbstractA recently developed theory allows to describe a porous solid with very large lacunae partially, or totally, filled by a uid inclusion like an atypical immiscible mixture which consists of a solid with an ellipsoidal microstructure and of a classical fluid. Here we investigate the condition of saturation when the fluid inclusion is incompressible.
A New Micromechanically Based Approach for the Elastic Response of Rubber–like Materials at Large Strains
Authors: Göktepe Serdar , Miehe Christian 
Published: June 2004

AbstractThe approach models the elasticity of a rubber–like materials based on micro–structure that can be symbolized by a micro–sphere. The proposed model incorporates both non–a.ne deformation of unconstrained chains and superimposed constraint e.ects of tube–like topological formations in a consistent manner. Framework of the constitutive modeling and numerical examples illustrating the excellent predictive capacity of the model are presented.
An Application of the Binary Model to Dynamic Finite Element Analysis
Authors: Haasemann Georg 
Published: June 2004

AbstractA new custom .nite element (FE) code based on the Binary Model is developed. The program is capable for investigation of the dynamic material properties of textile reinforced composites such as during impact. Therefore, the established formulation of the Binary Model for boundary value problems in Ref. [1,2,3] is enhanced to initial value problems. Regarding the investigation of the impact behavior, the program provides an apt .exibility in determination of boundary conditions. The calculations of di.erent models show the precision and reasonableness of the results from this FE program.The work done for this paper is partially sponsored by the German Research Community (DFG) in the context of the priority program (SPP) no. 1123.
Geometrically nonlinear homogenization analysis of hyperelastic solid foams
Authors: Hohe J. , Becker W. 
Published: June 2004

AbstractThe present study is concerned with the macroscopic material response of solid foams and other highly microheterogeneous solids in the finite strain regime. For the homogenization of the microstructure, a strain energy based procedure is proposed. This procedure is subsequently employed for the analysis of the macroscopic behavior of two‐dimensional model foams. Distinct effects of a deformation induced cell wall re‐alignment are observed which cannot adequately be included in pure small strain analyses.
On the interrelation of the basic laws of continuum mechanics
Authors: Kienzler Reinhold , Herrmann George 
Published: June 2004

AbstractIt has been shown by the present authors in a recent paper [1] that if some conservation and balance laws of continuum mechanics are represented in a 4 × 4 form, balance of linear physical momentum (i. e., stress) and balance of mass become closely linked. This seemingly novel result was reached in a completely ad‐hoc fashion by treating time on the same level as the spatial coordinates, and not as parameter, as it is usually done.In order to place the above ad‐hoc result on a firmer foundation and since it is in the theory of relativity that space and time are considered on the same footing, an attempt is made to derive several tensors of continuum mechanics in a systematic manner as 4 × 4 invariant objects.
Analytical solution of a plate bending problem using symbolic algebra
Authors: Kovács Ádám 
Published: June 2004

AbstractThe estimation of critical voltage in a capacitive micro‐switch leads to a thin plate bending problem. This paper deals with the correct mathematical formulation taking into account deflection‐dependent electrostatic force. The relative simple geometry allows the reduction of the structure to a beam problem. With the use of Ritz‐method and the variational symbolic program Mathematica analytical closed form solutions have been obtained. Polynomial and trigonometric trial functions have been used to determine the deflection of the plate. It has been proved, that the critical collapse voltage is much overestimated, if constant electrostatic forces are assumed.
Boundary Value Problems of the Theory of Thermoelasticity with Microtemperatures
Authors: Svanadze Merab 
Published: June 2004

AbstractThe boundary value problems of the steady oscillations of the linear theory of thermoelasticity with microtemperatures are investigated. The uniqueness and existence theorems of solution of the boundary value problems by means of the boundary integral method (potential method) are proved. The Sommerfeld‐Kupradze type radiation conditions are established. The existence of eigenfrequencies of the interior homogeneous boundary value problems of steady oscillations is studied.
Kontaktprobleme elastischer Walzen in nichtsymmetrischer Kontaktsituation
Authors: Walter H. , Braun M. 
Published: June 2004

AbstractUntersucht werden die ebenen Spannungen und Verschiebungen zylindrischer Walzen in nichtsymmetrischen Kontaktsituationen. Für eine Walze mit starrem Kern und eine elastische Vollwalze werden das Verschiebungs‐ und Spannungsfeld sowie die Randlasten als Fourier‐Reihen im Polarwinkel entwickelt. Unter der Voraussetzung linearer Elastizität sind die Ansätze für nichtsymmetrische Lastsituationen mit komplexen Koeffizientenfunktionen darstellbar. Der Anpreßvorgang erfolgt quasistatisch, muß aber wegen der Ausbildung von Haft‐ und Gleitbereichen inkrementell betrachtet werden.
On modelling of dynamic problems for elastic periodic plates
Authors: Wozniak Czeslaw , Wierzbicki Ewaryst 
Published: June 2004

AbstractThe subject of analysis are thin elastic plates with a periodic structure along the midplane. The aim of this contribution is to formulate a new effective 2D‐model of the plate, i.e. a 2D‐model represented by equations with constant coefficients. It is assumed that the period lengths are of an order of the mean plate thickness.
Mathematical models for elastodynamics of biperiodic layered composites
Authors: Wozniak Margaret , Wozniak Czeslaw 
Published: June 2004

AbstractBy a biperiodic composite we mean a composite solid which has a plane periodic structure and the properties of which are constant in the direction normal to this plane. The aim of the contribution is to formulate a certain new mathematical model describing the macroscopic (overall) behaviour of biperiodic composites and to apply this model to dynamics of laminates with a periodically waved laminae.
Numerical Modelling of Contact Problems with Application to Porous Media
Authors: Yang F. , Ehlers W. , Markert B. , Ammann M. 
Published: June 2004

AbstractContact problems are highly non‐linear because of the non‐penetration inequality in the contact interface. To solve such problems, different constraint methods are used to transform the inequality into an equality problem [4]. Concerning the contact of two isotropic fluid‐saturated porous solids which consist of an immiscible mixture of a solid skeleton and a fluid pore content [3], the non‐penetration constraint can be applied to the mixture approach by accounting additionally for the pore‐fluid interchange between the contacting porous solids. Except for the contact between the solid skeletons of two solids, it is important to determine the interaction forces exerted by the pore‐fluid on the pore‐fluid and the porous skeleton. In this contribution, it is assumed that at the permeable contact boundaries, the fluid effective pressure and the fluid mass flux across the surface are continuous [1].
3D rheological model of transversal isotropic elastoplastic body
Authors: Naumov Victor , Palmov Vladimir , Schrefler Bernard 
Published: June 2004

AbstractA 3D theory of microplasticity for an anisotropic elastoplastic body is presented. This theory is proposed for the phenomenological description and analysis of deformation of a superconducting cable under the transversal cyclic loading. Obtained constitutive equations reflect the possibility to describe hysteresis loops during cyclic loading of the material. They reflect the fact that these hysteresis loops don't depend on the strain rate. Developed theory deals with phenomenological anisotropy of elastoplasticity which is a characteristic property of the superconducting cable. This cable consists of a large number of strands oriented in general along the cable axis.
Interparticle contact forces in fine cohesive powders. Theory and experiments
Authors: Quintanilla M. A. S. , Castellanos A. , Valverde J. M. 
Published: June 2004

AbstractThe flow of fine powders is strongly influenced by interparticle contact forces. Depending on the interparticle load force the contact behavior can be elastic, fully plastic or elasto‐plastic. We propose a model for the elasto‐plastic loading regime that yields a nonlinear dependence of the interparticle adhesion force on the interparticle load force. Interparticle forces are also obtained experimentally. Theoretical results are in reasonable agreement with experimental data.
Transverse Force at the Yield Hinge during End Controlled Plane Bending and the Influence of its Neglect on the Shape Error
Authors: Reigl Martin , Lippmann Horst 
Published: June 2004

AbstractEnd controlled plane bending is an air bending process for tubes, profile bars and sheet metal, where the work‐piece is clamped at its ends only and where its prescribed final shape is reached by the controlled motions of the chuckings. The corresponding deformation is generated by moving a yield hinge or a yield zone from one end of the work‐piece to the other [1]. In this way many kinds of prescribed final shapes can be obtained like, among others circular, plane spiral, or elliptic arcs, which was proved by experiments [2]. The transversal force disappears in the moving yield hinge in the case of bending a circular arc. In many other cases, the transversal force is small compared with the normal force and can therefore be neglected. This simplifies the control software and reduces restrictions on the material law. However if the prescribed final shape has a strong curvature gradient, this simplification can lead to a remarkable shape error and will then not be allowable. The shape error depends also on the bending force, which is a free parameter in the bending process. On the example of bending a brass bar with L‐shaped cross section into a quarter elliptic arc, the shape error is quantified in dependence of the bending force.
Ein mikro‐polares Modell für Fasersuspensionsströmungen und dessen erste numerische Abschätzung
Authors: Altenbach Holm , Dyogtyev Oleksandr , Naumenko Konstantin , Zhilin Pavel 
Published: June 2004

AbstractFür die Festigkeit eines Bauteils aus kurzfaserverstärktem Polymer ist die Orientierung der Fasern entscheidend. Zur Vorhersage der Ausrichtung von Fasern benötigt man ein Modell für die der Strömung der Suspension. Nachfolgend wird ein mikropolares Modell für das Fließen von Suspensionen mit Fasern und dessen erste numerische Abschätzung diskutiert.
On the modelling of nonlinear electro‐mechanical coupled ferroelectrica
Authors: Romanowski H. , Schröder J. 
Published: June 2004

AbstractIn this contribution we discuss a simple phenomenological model for an assumed transversely isotropic ferroelectric crystal. We focus on the theoretical formulation and numerical treatment of the coupled electro‐mechanical behaviour. The main goal of this investigation is to capture the main characteristics of nonlinear ferroelectrica, such as the polarization‐electric‐field and the quadratic strain‐electric‐field (butterfly) hysteresis loops. The history dependency is modelled via two internal variables, the irreversible polarization and its conjugated irreversible electric‐field.
A Macroscopic Erosion Model
Authors: Steeb H. , Diebels Stefan 
Published: June 2004

AbstractWe present a continuum‐mechanically based model to describe erosion/deposition, growth/atrophy and remodeling phenomena. The considered model is based on the thermodynamically consistent Theory of Porous Media. The mixture is assumed to consist of a solid constituent, a fluid constituent and an abrasive constituent containing the fluidized particles. The abrasive process is described by a phase transition modeled in terms of mass exchange between the solid and the abrasive constituents. The balance equations of the present model are formulated in a general setting within the material space. Assuming several a‐priori restrictions for some specific applications and evaluating the balance of entropy specializes the constitutive equations for the considered model.
Zur Anwendung elasto‐plastischer Schädigungsmodelle im Stahl‐/Stahlbeton‐Verbundbau
Authors: Schröder K.‐U. , Nasdala L. , Rothert H. 
Published: June 2004

AbstractDurch die steigenden Anforderungen hinsichtlich Wirtschaftlichkeit und Komplexität an moderne Bauten rückt die Berücksichtigung nichtlinearer Werkstoffeigenschaften im Rahmen der Berechnung und Lebensdaueranalyse immer weiter in den Blickpunkt der Anwendung. Ein Bereich, in dem das nichtlineare Tragverhalten wesentliche Auswirkungen auf Bemessung und Konstruktion der Bauteile hat, ist der Stahl‐/Stahlbeton‐Verbundbau. In diesem Artikel wird ein elasto‐plastisches Schädigungsmodell für den Beton vorgestellt. Die Anwendung dieses Modells erfolgt im Rahmen der Simulation des Tragverhaltens eines Kopfbolzendübels eines Verbundträgers. Dieser Kopfbolzendübel ist auf den Stahlträger aufgeschweißt und dient der Schubübertragung zwischen Stahlträger und Stahlbetonplatte.
State of stress around a crack close to the boundary in a Rayleigh wave zone
Authors: Wille Ralf 
Published: June 2004

AbstractThe problem for an elastic half‐plane with a crack close to the boundary, located in a zone of Rayleigh surface waves, is generalized for a half‐plane with a crack obliquely oriented to the boundary. Fourier integral transformations are used to reduce the problem to the solution of a system of two coupled singular integral equations. The stress intensity factors are determined and related to the frequency of the external loads.
A 3‐D Model for Finite Viscoelsatic Swelling of Charged Tissues and Gels
Authors: Acartürk Ayhan , Ehlers Wolfgang , Abbas Ibrahim , Markert Bernd 
Published: June 2004

AbstractMaterials like soft biological tissues undergo large viscoelastic deformations during the swelling process. Following this, it is the goal of this contribution to merge the advances of finite viscoelasticity laws and the state of the art in electrochemical swelling theories within a well‐founded multiphasic concept. The numerical treatment is carried out fully 3‐d in the framework of the FEM.
Finite elements in shell analysis: A comparison of 3D‐p‐ and higher order shell elements
Authors: Nachname Christian , Hommel Jan‐Hendrik , Meschke Günther 
Published: June 2004

AbstractThe considerable progress in computational power has increased the attractivity of 3D‐p‐finite‐elements as a versatile tool in structural analysis. Due to its flexibility, the lack of various locking phenomena inherent to low order shell elements and the possibility of an a posteriori error assessment, 3D‐p‐finite‐elements have become an attractive alternative to the h‐method even for analyses of thin‐walled structures. In this paper a comparison of 3D‐p‐ and higher order shell elements concerning aspects of accuracy and efficiency is presented.
Mehrgitterberechnungen von nichtlinearen Hohlstrukturen
Authors: Bitzenbauer J. , Schweizerhof K. 
Published: June 2004

AbstractDie Finite Elemente Untersuchung von aus Hohlzellen aufgebauten Körpern mit nichtlinearem Materialverhalten führt bei durchgängiger Diskretisierung der Mikrostrukturen üblicherweise auf sehr grosse Gleichungssysteme. Als eine effiziente Lösungsmethode empfehlen sich Mehrgittermethoden. Damit ist im Gegensatz zur rein homogenen makroskopischen Betrachtung die Berücksichtigung lokaler Effekte (z.B. in Grenzschichten) möglich. Anders als bei der Homogenisierung können mit Hilfe des vorgestellten Konzeptes auch komplett aperiodische Strukturen betrachtet werden. Während im klassischen Multigridverfahren die minimale Anzahl der zur Geometriebeschreibung notwendigen Finiten Elemente von der Geometrie selbst abhängig ist, besteht ein gröbstmögliches Gitter bei der Composite Finite Elemente Methode (CFE, [1,2,3]) aus einem Element. Als Anwendungsbeispiel dient ein Hohlkörper mit aperiodischem nichtlinearen Verhalten.
Finite element simulation of rubber‐like material behaviour under consideration of its microscopic structure
Authors: Böl M. , Reese S. 
Published: June 2004

AbstractThe structure of rubber‐like materials is characterized through chain‐like macromolecules which are linked together at certain points. This special design leads to a completely random three‐dimensional network. There exist several ways to specify rubber‐like material behaviour. Many scientists use the tool of statistical mechanics to transfer the information from the micro level to the macro level. In this context, one should mention e.g. the work of Treolar & Riding [1979] (full network theory) or the eight‐chain model suggested by Arruda & Boyce [1]. In the present contribution, the step from the micro level to the macro level is done by means of the finite element method. For this purpose, we derive a unit cell consisting of one three‐dimensional tetrahedral finite element and six truss elements lying on every edge of the tetrahedron. The truss elements represent the material behaviour of a certain group of polymer chains, whereas the tetrahedral elements ensure incompressibility. So, using a finite element model with a sufficiently high number of unit cells, we are able to model the well‐known macro‐mechanical material behaviour of rubber‐like polymers.
A Poroelastic Mindlin‐Plate
Authors: Busse Anke , Schanz Martin , Antes Heinz 
Published: June 2004

AbstractThe numerical treatment of noise insulation of solid walls has been an object of scientific research for many years. The main noise source is the bending vibration of the walls usually modeled as plates. Generally, walls consist of porous material, for instance concrete or bricks. Therefore, a poroelastic plate theory is necessary. A theory of dynamic poroelasticity was developed by Biot using the solid displacements and the pore pressure as unknowns. After formulating the poroelastic theory for thick plates, Mindlin's theory, a variational principle for this poroelastic thick plate model is developed. This is the basis of a Finite Element formulation.
An anisotropic finite 3D beam element for the analysis of piezoelectric structures
Authors: Butz A. , Klinkel S. 
Published: June 2004

AbstractA finite element formulation for a 3D beam is presented to model rod like piezoelectric structures. Piezoelectricity is described by a mixed field theory that couples mechanical and electrical quantities. In this work the coupling between the mechanical stress and the electric displacement is considered. Therefore a 3D beam element formulation with nine degrees of freedom per node is introduced. Due to the poling process, the piezoelectric materials have anisotropic material properties which are taken into account in the presented beam formulation. Further more we suggest a special approximation for the electric potential through the cross‐section of the beam. An excentric beam formulation is used to model the layerwise design that is often found on piezoelectic structures.
Alternative Definitions of Micro–to–Macro Transitions in Particle Aggregates of Granular Materials
Authors: Dettmar Joachim , Miehe Christian 
Published: June 2004

AbstractAn alternative approach to the modelling of the overall macroscopic response of granular materials is presented based on micro–macro transitions. A homogenized macro–continuum is considered with locally attached granular microstructures. The new developments include a consistent transfer of micro–macro transitions from continuous to particle microstructures with a new overall macro–stress definition. Secondly, a new class of boundary conditions for displacements/ rotations on prescribed boundary–frame particles is presented that yields upper and lower bounds with regard to the aggregate stiffness. Thirdly, a unified implementation of the displacement/ rotation boundary constraints by a penalty method is developed that proves to be a convenient computational tool in explicit codes.
A DAE‐approach applied to elastic‐plastic material behavior using FEM
Authors: Ecker Steffen , Baaser Herbert , Gross Dietmar 
Published: June 2004

AbstractSimulating elastic‐plastic material behavior with the finite element method (FEM), two different types of equations appear. The spatial discretization of the considered domain leads to a system of nonlinear equations for the unknown displacements, whereas the time‐evolution of the internal variables describing the inelastic state is governed by first order differential equations. Altogether a system of differential‐algebraic equations (DAE) has to be solved. In the following, the DAE‐concept is used to describe rate‐independent, associated plasticity, but it can also be applied to visco‐plastic material behavior. The advantage of using a BDF2‐method for time integration of the internal variables is emphasized and the differences between the classical 'elastic predictor – plastic corrector' approach and our method are pointed out. A comparison between both methods in terms of computational efficiency will also be presented. The numerical implementation is done in DAEdalon [2], a free available FEM‐Package.
Development of a Contact Element for Finite Deformations using the MortarMethod
Authors: Fischer Kathrin A. , Wriggers Peter 
Published: June 2004

AbstractThe Mortar method is based on domain decomposition techniques that allow powerful solutions of PDE's for nonmatching meshes. The variational formulation of the contact contributions is expressed with Lagrange multipliers which are discretized with special interpolation functions. A segmental contact description is used to dicretize nonmatching meshes. Applying this method to contact problems in engineering, attention has to be paid to finite deformations and curved bounded regions. With regard to later applications of higher order interpolation functions, a simple 2‐dimensional formulation with linear interpolation functions for the multipliers and the displacements is presented for frictional contact problems.
A Micro‐ Thermomechanical coupled Finite‐Element Model for the Simulation of Particulate Cellular Solids at Finite Strains
Authors: Freßmann Dirk , Wriggers Peter 
Published: June 2004

AbstractA numerical model for the simulation of the complex material behaviour of particulate cellular solids on the mesolevel of single foam pellets is presented. During the deformation process, extremely large local deformations can occur, that are resolved using a displacement‐based arbitrary Lagrangian‐Eulerian approach. A special treatment of the thermomechanical problem is able to account for the highly non‐linear thermomechanical material behaviour of the foam material.