bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical description of elastic‐plastic behavior of saturated porous media
Authors: Skolnik J. 
Published: March 2011

AbstractIn this paper, the numerical description of the elasto‐plastic behavior of saturated porous materials, consting of a solid skeleton with liquid filled pores, will be discussed. In particular, frictional materials will be described which show small elastic but mostly plastic deformations.The elastic‐plastic deformable solid skeleton and the liquid are assumed to be incompressible, where the liquid does not exhibit viscous properties.The description of the stress state is done within the framework of the geometrically‐linear theory, because small deformations are assumed The elastic strain state shall be expressed by Hooke 's law and the plastic strain state with the help of a single surface yield criterion as well as a non‐associated pow rule.The numerical description of the initial‐ and boundary‐value problems is done by the finite element method within the framework of the standard Galerkin procedure.
Numerische Simulation von porösen Medien
Authors: Weiss W. 
Published: March 2011

AbstractGroße Bereiche der Ingenieurwissenschaften erfordern die mathematische Beschreibung und die numerische Simulation von Rand‐ und Anfangswertproblemen eines saturierten porösen Körpers. Poröse Medien unterscheiden sich von Einkomponentenkontinua durch ihren heterogenen Aufbau. Im Beitrag werden zunächst die Grundgleichungen für ein ternäres Modell (poröser Festkörper, Flüssigkeit und Gas) aufgestellt. Diese werden anschließend für die numerische Simulation aufbereitet. An zwei Beispielen wird das mechanische Verhalten des dreikomponentigen porösen Mediums unter Belastung dargestellt.
Transition from Quasiperiodicity to Chaos for Three Coaxial Vortex Rings
Authors: Blackmore D. , Knio O. 
Published: March 2011

AbstractThe dynamics of three coaxial vortex rings of strengths Γ1, Γ2 and Γ3in an ideal fluid is investigated. It is proved that if Γj, Γj + Γk and Γ1+ Γ2 + Γ3 are not zero for all j,k = 1,2,3, then KAM and Poincaré Birkhoff theory can be used to prove that if the distances among the rings are sufficiently small compared to the mean radius of the rings, there are many initial configurations of the rings that produce quasiperiodic or periodic motions. Moreover, it is shown that the motion become chaotic as the inter‐ring distances are increased relative to the mean radius.
Comparison of Numerical Schemes Applied to CAA Problems
Authors: Ewert R. , Meinke M. , Schröder W. 
Published: March 2011

AbstractTo compare numerical methods and boundary conditions for computational aeroacoustics (CAA) two‐dimensional aeroacoustic benchmark problems are solved. The numerical methods are the dispersion relation preserving scheme (DRP) of Tam et al. [1] and the compact finite difference scheme proposed by Lele [2]. The acoustic boundary conditions applied are the non‐reflecting boundary condition of Thompson [4,5] and the asymptotic boundary condition of Tam [2]. The benchmark problems used describe the propagation of acoustic, vorticity and entropy waves relative to a mean flow with varied flow direction.
Numerical Simulation of Normal‐ and Oblique‐Shock Vortex Interaction
Authors: Thomer O. , Schröder W. , Meinke M. 
Published: March 2011

AbstractThe dependence of the breakdown topology on the shock‐vortex interaction conditions is numerically investigated. Based on solutions of the Euler equations the unsteady three‐dimensional flow field is studied at several freestream Mach numbers and for normal and oblique shocks. The results of the finite‐volume method using the AUSM approach indicate a strong dependence of the recirculation region downstream of the shock on the shock induced pressure gradient and on the vortex strength.
Lokalisierte Schwingungsformen langer Platten auf der Wasseroberfläche
Authors: Azalinov D. 
Published: March 2011

AbstractHeutzutage werden verschiedene Objekte auf der Wasseroberfläche konstruiert, unter anderem sogenannte Schwimmflugplätze, wo man das Verhalten langer dünner Platten auf seichtem Wasser als erste Annäherung studieren kann. Zu Phänomenen, die bei Verwendung solcher Strukturen entstehen, gehört auch das Phänomen der Wellenlokalisierung im Gebiet der Struktur. Unser Ziel ist nicht nur die Bedingungen zu finden, bei denen dieses Phänomen der Wellenlokalisierung am Gebiet der Platte und ihre Resonanz möglich sind, sondern auch zu zeigen, daß ähnliche Effekte für praktisch alle Körper mit einem Einschluß kennzeichnend sind. Es ist offensichtlich, daß die Platte auf der Wasseroberfläche auch als ein Einschluß betrachtet werden kann.
Energy transfer from low to high frequency modes due to repeated impacts
Authors: Belyaev A. K. 
Published: March 2011

AbstractNumerical simulation of energy exchange between the vibration modes in an elastic bar colliding with rigid walls is performed. After a large number of impacts the vibration energy is observed to be equally distributed over the degrees of freedom. Since the energy equipartition is typical for the thermal motion, the present study is useful for understanding the mechanism of transfer of mechanical energy into thermal one. The concept of the impact oscillator is generalised to mechanical systems with distributed parameters.
Variational Approach to Contact, Friction and Wear Problems
Authors: Zmitrowicz A. 
Published: March 2011

AbstractModern methods of analysis of contact problems are based on the variational approach which together with the finite element method expand possibilities of analysis in many cases. In this contribution, generalizations of classical variational formulations are given in the case of contact of rubbing and wearing solids. Using the finite element method, discretized forms of the Variational functional are presented.
Detection of Defects in a Plate Using Rayleigh‐Lamb Waves
Authors: Conry M. J. , Crane L. J. , Gilchrist M. D. 
Published: March 2011

AbstractNondestructive testing of materials is essential wherever they are used in safety critical applications. Conventional ultrasonic techniques, such as C‐scanning, generally use waves propagating normal to the plane surface. While accurate, such methods are slow for structures with large plane areas. The use of longitudinal waves offers the possibility of quicker testing of such structures.This paper considers the reflection of low frequency Rayleigh‐Lamb waves by a two dimensional, centrally embedded vertical defect in aluminium plate. A numerical method is used, based on results from dimensionless analytical work. It is shown that such longitudinal ultrasonic waves can successfully detect structural defects.
Numerical Simulation of Interface Debonding during Fibre Pull‐Out Tests
Authors: Döbert C. , Mahnken R. , Stein E. 
Published: March 2011

AbstractThe Pull‐Out experiment is used for determination of the bond strength between fiber and matrix an fiber reinforced composites. An interface crack growth between both constituents and a contact friction behaviour on the cracked area can be observed in the experiment. In our contribution this mechanical behaviour of the interface is simulated in the framework of Interface Damage Mechanics. The displacement discontinuities during the progressive decohesion are related to constitutive equations extended by a damage model. The contact/friction behaviour after complete separation is described by a friction model analogous to the classical theory of plasticity.
Bruchmechanische Analyse piezoelektrischer CT‐Proben
Authors: Gruebner O. , Kamlah M. 
Published: March 2011

AbstractIn diesem Beitrag werden Finite‐Elemente‐Analysen für elektromechanisch belastete piezoelektrische CT‐Proben vorgestellt. Insbesondere wird dabei auf verschiedene Möglichkeiten eingegangen, die elektrischen Randbedingungen von Rissen in Piezokeramiken zu modellieren, wobei der Einfluß der Permeabilität des Rißmediums auf die Ermittlung der bruchmechanischen Kenngrößen diskutiert wird.
Compressive Behaviour of Metal‐Matrix Composites: Accuracy of Homogenisation
Authors: Guz I. A. 
Published: March 2011

AbstractAsymptotic accuracy of the continuum theory of plastic fracture under compassion for the metal matrix composites with periodic structure is proved. The particular mode of stability loss, which corresponds to the continuum approximation is determined within the model of piecewise‐homogeneous medium. The investigation is carried out for three‐dimensional non‐axisymmetrical problems.
Optimal Design of Vibration Absorbers
Authors: Glora M. , Bestle D. 
Published: March 2011

AbstractThe tendency of reducing energy consumption leads to extensive use of lightweight structures in vehicle dynamics. As a consequence bodies of cars and trains become sensitive to structural vibrations. For damping of such vibrations, the use of passive absorbers is a common approach. Passive systems, however, have to be tuned for a given resonance frequency of the structure and are sensitive to changes of this frequency due to variations in loads or excitation. Mechatronics enables the use of actively controlled absorption systems that don't lack this disadvantage.
Elasto‐plastic Analysis of Fracture Specimens using the Boundary Element Method
Authors: Potrc Iztok , Sadl Rudolf 
Published: March 2011

AbstractIn general crack problem, the geometry and loading encountered are too complex for the determination of the fracture parameters analytically. To this end, numerical methods have been developed as possible solution. The boundary element method, used in this paper is one of the powerful numerical methods. An elasto‐plastic analysis of fracture specimens is performed. The welded specimen fracture behaviour and its deviation regarding the parent material is investigated. The obtained results are compared whit the experimental results and the results given by FEM.
A threedimensional boundary element analysis of elasto‐plastic cracked prolems
Authors: Iztok Potrc , Janez Kramberger 
Published: March 2011

AbstractBased on the theoretical background, the formulation for the three‐dimensional elasto‐plastic analysis has been enhanced and implemented in the computer program. The algorithm utilities the initial stamen approach to satisfy the material non‐linearity. The discrimination inculpates the continues and the discontinuous boundary elements. Also included are the domain cells with the linear and quadratic approximation. The non‐linear boundary element results are presented to demonstrate the accuracy and usefulness of the method.
Fracture Parameter for Thermoplasticity Relative to Material Scaling
Authors: Sansen P. , Dufrenoy P. , Weichert D. 
Published: March 2011

AbstractThis study deals with a fundamental approach on energetic formulation of a rupture criterion of a solid under thermoplastic solicitation. This approach consists of a calculation of an energy from which will appear a macroscopic crack for a given cycle of solicitation. On the basis of the Noether's theorem, this study is undertaken in the case of the dilatation symmetry, by taking into account plasticity and thermochemical loading (M modified integral). This integral emanates from a discrete lagrangian describing the thermoinelastic system from classical field theory. It represents a conservation law analogues to the Budiansky and Rice interpretation.
Ductile Fracture of honeycombs
Authors: Schmidt I. , Fleck N. A. 
Published: March 2011

AbstractCrack growth initiation and subsequent resistance in a hexagonal honeycomb made out of ductile base material is investigated in a numerical study. The elasto‐plastic base material is characterized by its yield strain, failure strain and the ratio of ultimate strength to yield strength, assuming a bilinear stress‐strain relationship. Of the base materials' fracture properties, only the specific fracture energy is prescribed. K‐Resistance curves are calculated under the assumption of small scale yielding.
A new approach for a 3D deep drawing using an Asymptotic Numerical method
Authors: Abichou H. , Zahrouni H. , Potier‐Ferry M. 
Published: March 2011

AbstractThis paper presents an Asymptotic Numerical Method (A.N.M.) to simulate a 30 bemispherical deep‐drawing of a circular sheet. An elastoplastic model based on the plasticity deformation theory is adopted The problem discretisation is performed by a shell finale element well adapted for problems involving large displacements and large rotations. A comparison with results obtained by the help of the industrial code Abaqus evaluates the performance and the interest of the method.
Valve gear refinement
Authors: Avsec J. , Marcic M. 
Published: March 2011

AbstractAfter the 3000‐hour engine test the manifestations of an intensive wear appeared on the exhaust side of valve gear. The paper describes a new type of valve gear cam ‐MULTICAM which consists of seven curves and allows an optimum cam design. In order to calculate the cinematic and dynamic values and to asses the minimum oil film thickness in the valve gear, the mathematical model was used. By means of the new cam design the Hertz pressures were reduced at the point of contact between the cam and the cam follower and the lubrication properties at the top of the cam were improved.
Adaptive Discretisation of Shell Problems
Authors: Axel Hecht , Carsten Carstensen , Darius Zarrabi 
Published: March 2011

AbstractA seven parameter Reißner‐Mindlin shell kinematic is employed for a elastoplastic material with hardening. The resulting nonlinear minimization problem is discretised within a finite element method on the mid surface of the shell. A posteriori error estimates are discussed and related adaptive algorithms are presented. Numerical examples illustrate the theoretical results.
Adaptive Methods for Euler and Navier‐Stokes Equations
Authors: KlikovÁ Alice 
Published: March 2011

AbstractThe numerical calculations show that the local fineness of the mesh has an important influence on the numerical results. In our contribution, two types of error indicators for Euler and Navier‐Stokes equations are presented. These indicators are used for adaptive refinement of the mesh and thus for improving the precision of the approximate solution and minimazing the computational time.
Aspects of Adaptive Remeshing Techniques in Finite Elasticity
Authors: Koch A. , Miehe C. 
Published: March 2011

AbstractOne of the major difficulties in applying the finite element method to boundary value problems of finite elasticity is the design of a suitable mesh in order to maximize the accuracy of the solution and to minimize the numerical cost. The basic problem in this context is the error estimation of the nonlinear problem. Our aim is to present possible a posteriori error estimators for finite elasticity which operate in the linear tangential space of the nonlinear problem.
Automatic derivation of sensitivity terms for mixed Galerkin‐collocation problems
Authors: Korelc J. 
Published: March 2011

AbstractThe paper presents the use of the SMS system (Symbolic Mechanics System) for the automatic derivation and coding of sensitivity terms in finite element analysis. General symbolic derivation of analytical sensitivity terms for general mixed Galerkin‐collocation problems is difficult due to the complex (implicit) interactions between different levels of computation. The approach implemented in SMS avoids this problem by combining several techniques: symbolic capabilities of Mathematica, automatic differentiation technique, simultaneous optimisation of expressions and stochastic evaluation of the formulae.
Re‐analyses of Tests on Snow Specimens by Means of Elasto‐Visco‐Plasticity Models
Authors: Liu W. N. , Meschke G. , Mang H. A. 
Published: March 2011

AbstractTo gain more insight into the mechanical behavior of snow for the purpose of numerical simulations of the traction mechanism of a rubber tread moving on a snow‐cowered road, three pertinent material models are investigated numerically by means of re‐analyses of tests on snow specimens. Based on a comprehensive comparison of the obtained results, one of these three models is found to be superior to the other two. The technical background of this work is the design of winter tires.
Zur inititalen Identifizierung von Verzweigungspunkten auf nichtlinearen Last‐Verschiebungspfaden
Authors: Mang H. A. , Helnwein P. 
Published: March 2011

AbstractMit Hilfe der konsistenten Linearisierung der klassischen Beulbedingung ist es vielfach möglich, Stabilitätsgrenzen auf nichtlinearen Last‐ Verschiebungspfaden ab initio mat für technische Zwecke ausreichender Genauigkeit abzuschätzen. Da sich für Verzweigungspunkte andere Schätzfunktionen als für Durchschlagspunkte als in einem bestimmten Sinn optimal erwiesen haben, ist es notwendig, die jeweils aktuelle Art der Stabilitätsgrenze ab initio zu identifizieren. In diesem Zusammenhang wird die Existenz zusätzlicher Orthogonalitätsrelationen zwischen sogenannten Verzweigungsmoden und den übrigen Eigenvektoren des zugrunde liegenden linearen Eigenproblems nachgewiesen.
Zur Analyse dynamischer Mehrdeutigkeitslösungen von nichtlinearen parametererregten Systemen
Authors: Hortel M. , Škuderová A. 
Published: March 2011

AbstractZUT Untersuchung von dynamischen Eigenschaften mechanischer Systeme mit kinematischen Bindungen, z.B. bei elastisch gelagerten Zahnradübersetzungsgetrieben, wird ein Approximationsverfahren skizziert, das auf der Transformation der Differentialrandwertaufgabe in ein Integrodifferentialgleichungssystem beruht.
Einspielanalyse von Verbundwerkstoffen
Authors: Schwabe F. , Hachemi A. , Weichert D. 
Published: March 2011

AbstractDas Einspielverhalten eines regelmäßig strukturierten heterogenen Verbundwerkstoffes wird untersucht. Dazu wird das Verhalten einer repräsentativen Einheitszelle des Werkstoffes betrachtet. Mat Hilfe der Homogenisierungstechnik wird der Übergang von Mikro‐ zu Makrostruktur hergestellt, so daß für den gesamten Werkstoff eine Aussage zum Einspielverhalten getroffen werden kann.
Generalisation of Boussinesq's Equation over Triangularly shaped Bases
Authors: Skrinar M. 
Published: March 2011

AbstractThe equation for the computation of stresses directly in an arbitrary point of the half‐space loaded with a linear load distributed over a rectangular base according to Boussinesq s equations that has been presented recently is applicable if the bases can be described with rectangular areas only. For nonrectangular bases the integration over an arbitrary quadrilateral with a uniform load was performed, but the procedure required enormous computational efforts and yielded only approximate results. The paper presents a new integration over a triangular area which allows the analysis of practically any polygonal base shape with a linear load, thus eliminating all limitations of shape and load.
Viscous Creep of Steel Structures in Fire
Authors: Srpčič S. 
Published: March 2011

AbstractWhen analysing the mechanical behaviour of steel structures at high environmental temperatures as expected in real fire, the viscous creep deformations may play a significant role. The paper presents the nonlinear analysis of steel planar beams and frames, subjected to time dependent temperature and mechanical loadings. In the FEM‐based numerical procedure, the viscous part of the total strain increment is described by the Williams‐Leir modification of Harmathy's equation of nonlinear viscous creep of steel. The numerical example shows the influence of the creep intensity on the mechanical response of a steel beam structure in hypothetical fire. Due to the creep softening, considerable increase of deflections can be expected at statically determinate structures and significant stress redistributions at statically indeterminate ones.
The general mechanics equation of the system with nonholonomic constraints
Authors: Osinski Z. 
Published: March 2011

AbstractThe paper presents the method for preparing the general mechanics equation and obtaining the equation of motion for the system with nonholonomic equations. The concept of generalised forces together with related quasicoordinates, quasivelocities and quasiaccelerations is applied. Presented form of the general equation is a uniform representation replacing equivalently known mechanics principles, This form of the equations is a good basis for the computer aided design incorporating symbolic calculus required for description of mechanical systems with nonholonomic constraints.
Eine verbesserte Beschreibung der Wirkungen nichtklassischer Dämpfung
Authors: Raue A. , Heuer R. 
Published: March 2011

AbstractIn der vorliegenden Arbeit wird die Schwingungsantwort yon Bernoulli‐Euler‐Balken mit externen viskosen Dämpfern unter‐sucht. Nach Anwendung der modalen Projektion unter Verwendung der Eigenformen des ungedämpften Balkens bleiben die beschreibenden Differentialgleichungen dämpfungsgekoppelt. Die Lösung wird iterativ mit den Koppeltermen als zusätzliche Anregung nach Abspaltung quasistatischer Anteile von der Gesamtlösung gefunden und der Lösung des Systems ohne Koppelterme gegenübergestellt. Speziell wird der beidseitig gelenkig gelagerte Balken unter zeitlich harmonischer Gleichlast und unsymmetrischer Dämpferanordnung untersucht.
Pseudo‐Shakedown viskoplastischer Flächentragwerke
Authors: Stoffel M. , Schmidt R. , Weichert D. 
Published: March 2011

AbstractWerden Flächentragwerke wiederholt Impulsbelastungen ausgesetzt, kann sich ein Grenzverhalten in ihren inelastischen Verformungen einstellen. In dieser Arbeit wird die Ursache dafür näher untersucht.
On the Dynamics of Washing Machines
Authors: Wagner F. , Pfeiffer F. 
Published: March 2011

AbstractThe mechanical model of a washing machine as an elastic multibody system is presented in this paper. According to the complexity of the machine parts the results of a finite element mode shape analysis are used to describe the elastic behavior. A procedure is presented to expand the Ritz seperation method for incorporating additional terms in the equations of motion resulting from shell or beam elements as well as from attached masses.
Zweibeiniges Technisches Gehen
Authors: Markus Baldinger , Bremer H. 
Published: March 2011

AbstractDer Bewegungsapparat ist das Instrument, mat dem der Mensch auf die Umwelt zugeht, um einerseits auf sie einzuwirken, andererseits sich selbst in ihr darzustellen. Wie wichtig uns Menschen dieser Bewegungsapparat ist wird uns erst bewußt, wenn durch besondere Umstände (Unfälle oder Krankheiten) diese Bewegungsmöglichkeiten eingeschränkt werden. Daher versuchen Techniker und Ingenieure seit Generationen, die Fähigkeiten dieser komplexen Bewegung durch eine geeignete mathematische Apparatur darzustellen und das Steuerungssystem durch eine entsprechende Regelungsstruktur zu ersetzen. In dieser Arbeit ward dieser Bewegungsablauf durch eine angemessene mathematische Beschreibung dargestellt, und die anschließenden Ergebnisse präsentiert.
Effet du gauchissement et des charges sur les instabilités des poutres à parois minces et à sections ouvertes
Authors: Kamal El. , Mohri F. , Roth J. C. 
Published: March 2011

AbstractOn s'intéresse au phénomène de déversement de poutres à parois minces et à sections ouvertes. Cette instabilité fait intervenir le comportement des poutres en flexion torsion avec gauchissement. Beaucoup de paramétres interviennent dans l'étude. On se limite à exposer l'incidence des conditions aux limites vis à vis du gauchissement et l'effet d'application des charges. Les solutions numériques par éléments finis utilisant les poutres spatiales avec gauchissement sont comparées aux solutions analytiques proposées dans ie règlement européen (EC3).