bluuebunny/crossref_metadata_2025_split huggingface dataset:
Untersuchungen zur werkstoffmechanischen Stabilität metallischer Faserverbundwerkstoffe mit geschädigter Struktur bei zyklischer thermomechanischer Belastung
Authors: Dressler R , Ismar H , Ripplinger W 
Published: May 2007

AbstractDas Verhalten eines faserverstärkten Bauteils mit metallischer Matrix wird unter zyklischer thermomechanischer Belastung simuliert. Die metallische Matrix des Verbundwerkstoffes wird durch ein weiterentwickeltes Zweiflächenverfestigungsmodell auf der Grundlage des Übergangsfließpotentials beschrieben, um die typischen nicht‐linearen Effekte zyklischer Plastizität und deren Temperaturabhängigkeit zu berücksichtigen. Es wird eine spröde, intermetallische Schicht zwischen Faser und Matrix angenommen, die sich linear‐elastisch verhält. Ohne ein neues FE‐Netz erzeugen zu müssen, können wir numerisch das Fortschreiten eines anfänglich existierenden Risses innerhalb der Zwischenschicht verfolgen. Auf der Grundlage dieses Werkstoffmodells untersuchen wir die werkstoffmechanische Stabilität an dem ausgewählten Beispiel eines faserverstärkten Rohers.
Optimal Control in Nonlinear Evolution Equations with Constraints
Authors: Kampowsky W. 
Published: May 2007

AbstractThis paper continues the investigations of the author [5] – [12] concerning optimal control of nonlinear evolution equations with monotone operators. Necessary optimality conditions are derived where additional constraints in a general from for the state and the control are allowed. As applications a Dirichlet boundary control problem and a time‐optimal problem are considered.
On the Stability in Obstacle Problems with Applications to the Beam and Plate
Authors: Miersemann E. , Mittelmann H. D. 
Published: May 2007

AbstractNew stability results are proved for solutions to variational inequalities with an eigenvalue parameter. These describe obstacle problems and rather general nonconstant obstacle functions are considered. Sufficient conditions are given for the solution bifurcating at the critical load to define a minimum of the associated energy functional. One of the results is that the stability behavior depends discontinuously on the obstacle. Applications to the beam and plate are given both in analytical and numerical form.
On the Method of Asymptotic Expansions for Plates
Authors: Molnárka Gy. 
Published: May 2007

AbstractThe method of asymptotic expansion is an efficient method for simplifying complicated mathematical problems. But if the small parameter is a geometric one the physical interpretation of the result is more difficult. Here we present a new asymptotic expansion connected with the equation describing the deformation of linear plates. The steps of this method can be physically interpreted analoguosly as in the earlier methods however the resulting equation is different.
Modellierung von Verdrängungsvorgängen in Laborversuchen
Authors: Aavatsmark I. 
Published: May 2007

AbstractEin Modell für eindimensionale Zweiphasenströmung in porösen Feststoffen wird aufgestellt. Unterschiedliche Randbedingungen für die Verdrängungsversuche des Flutens, der kapillaren Aufsaugung und der Schweredränage sind nötig. Die sich ergebenden Anfangsrandwertaufgaben besitzen starke Nichtlinearitäten und Singularitäten. Die einzelnen Glieder der Differentialgleichung und der Randbedingungen werden erörtert. Bei der Diskretisierung werden die mathematischen Eigenschaften der Differentialgleichung herangezogen. Somit wird das diskrete Verfahren unter Berücksichtigung der Erhaltung, der Flußkonsistenz und der Monotonie aufgestellt. Wegen der Monotonie sind in der Nähe der stationären Lösung sehr große Zeitschritte erlaubt. Abschließend werden Beispiele numerischer Simulationen der genannten Verdrängungsvorgänge gegeben.
Dynamic Buckling Estimates for Discrete Systems under Step Loading
Authors: Kounadis A. N. , Mallis J. , Raftoyiannis J. 
Published: May 2007

AbstractThis paper deals with nonlinear dynamic buckling analysis of imperfection sensitive or more generally limit point discrete systems under suddenly applied loads of infinite duration. Static and dynamic stability conditions and respective buckling estimates for such systems without or with damping are properly established. It was shown that the static stability criterion associated with zero total potential energy and negative definite second variation leads always to exact dynamic buckling loads for one‐degree‐of‐freedom systems if damping is ignored, and to lower bound buckling estimates if this effect is included. It was also found that such a static criterion leads always to lower bound dynamic buckling estimates for multi‐degree‐of‐freedom systems with or without damping. Moreover, it was established that dynamic buckling associated with an unbounded (damped or undamped) motion occurs for that magnitude of the load for which the velocity of the phase point corresponding to any one of the generalized coordinates of the system vanishes for the first time.
Response of a Viscous Liquid Column to Pitching‐ and Roll‐Excitation in Zero‐Gravity Environment
Authors: Bauer H. F. 
Published: May 2007

AbstractThe response of a viscous liquid column to pitching‐ and roll excitation has been determined. For a simplified analytical treatment the no‐slip condition at the top and the bottom of the liquid column has been abandoned in the pitching case. The responce of the free liquid surface displacement and the velocity distribution has been determined as a function of the reduced frequency Ωa2/v for various surface tension parameters σa/ϱv2. Due to viscosity the resonance amplitudes are finite and disappear for higher modes and shorter liquid bridges. The velocity distribution, effective moment of inertia and effective damping was obtained for the liquid in roll excitation.
Behaviour of a System Under Harmonic Excitation Inside an Equilibrium Zone
Authors: Klepp H. J. 
Published: May 2007

AbstractA multi‐body‐system in form of a deformable parallelogram with friction affected constraints is considered. The system possesses an equilibrium zone. Under the action of a harmonic excitation the system migrates inside the zone. By numerical simulation it is found that the directions and speeds of migration are indicated by the shifting tendency functions established for the equilibrium zone.
Eine FEM‐Methode für ein quasistationäres elektrisches Feld
Authors: Lucht W , Radke Th. 
Published: May 2007

AbstractAuf der Basis der quasistationären Maxwellschen Gleichungen wird für einen elektrisch betriebenen Reaktor das elektrische Feld E ermittelt. Es wird für einen praktisch realistischen Fall eine auf einem beschränkten Gebiet abgeschlossene Randwertaufgabe für E formuliert, für die eine Finite‐Elemente‐Approximation angegeben wird.
Block Runge‐Kutta Methods on Parallel Computers
Authors: van der Houwen P. J. , Sommeijer B. P. 
Published: May 2007

AbstractIn this paper block methods for solving ODEs on parallel computers are constructed. Most block methods found in the literature produce approximations to the exact solution at equidistant points. Here, we allow that the approximations correspond to nonequidistant points like the intermediate approximations computed in Runge‐Kutta methods. This approach enables us to improve the order of accuracy. We concentrate on explicit methods such that they are suitable for use on parallel computers.
On the Iterative Solution of van Roosbroeck's Equations
Authors: Gajewski H. , Gärtner K. 
Published: May 2007

AbstractIn 1950 VAN ROOSBROECK has derived a system of nonlinear partial differential equations which is used now generally as the base for numericla modelling carrier transport in semiconductors. In this paper we deal with the iterative solution of the linearized van Roosbroeck system. This problem arises from the numerical realization of Newton's method as well as the small‐signal analysis of devices.
Optimal Design of an Elastic or Elasto‐plastic Beam with Unilateral Elastic Foundation and Rigid Supports
Authors: Hlaváček I. , Lovišek J. 
Published: May 2007

AbstractA class of optimal design problems is considered, where the state problem is governed by a variational inequality. The latter includes a nonlinear monotone operator, the coefficients of which are chosen as the design (control) variables. Moreover, the set of admissible functions depends on the control, as well. Existence of an optimal design is proven on an abstract level. Some applications are presented to the optimization of a beam on a unilateral elastic foundation. Finite element approximations are proposed and a convergence result is proven.
Irreduzible Invarianten eines Tensors vierter Stufe
Authors: Betten J. , Helisch W. 
Published: May 2007

AbstractNach Hilberts Theorem besitzt jeder Tensor eine Integritätsbasis, d. h. eine begrenzte Anzahl von Invarianten, derart, daß jede beliebige Invariante sich als ganze rationale Funktion der Elemente dieser Integritätsbasis darstellen läßt. Anders als beim Tensor zweiter Stufe ist eine solche Integritätsbasis für einen Tensor vierter Stufe bisher unbekannt. Als Vorstufe zu deren Bestimmung werden im folgenden Aufsatz Systeme von irreduziblen Invarianten eines Tensors vierter Stufe im zwei‐ und dreidimensionalen Euklidschen Raum aufgestellt.
Ebene Wirbelfelder bei kompressiblem Hauptstrom
Authors: Albring W. 
Published: May 2007

AbstractUrsprünglich waren Wirbelfelder als Integrale der Kontinuitätsgleichung und der Navier‐Stokes‐Gleichung für Strömungen mit konstant bleibender Dichte eingeführt worden. Die Strömungsakustiker hatten diese Wirbelfelder zum Berechnen von Schallquellen benutzt und gefragt, wie sie modifiziert werden müß für eine Gasströmung mit veränderlicher Dichte, in der die Hauptgeschwindigkeit nicht klein gegenüber der Schallgeschwindigkeit ist. Es zeigt sich, daß die bekannten Wirbelfelder unverändert auch in Gasströmungen benutzt werden dürfen, solange die Wirbelgeschwindigkeit klein gegenüber der Hauptgeschwindigkeit und der Schallgeschwindigkeit bleibt.
On the Three‐Dimensional Cerruti Problem for an Elastic Nonlocal Half‐Space
Authors: Nowinki J. L. 
Published: May 2007

AbstractThe classical Cerruti problem of a half‐infinite elastic space acted upon by a tangential surface load is examined in its nonlocal context taking the constitutive equations in the Kroener‐Eringen form. After a brief discussion of the values of the nonlocal moduli, a summary of the nonlocal Kelvin problem serving as a basis for the solution of the Cerruti problem is given. By appeal to Westegaard's twinned gradient procedure (determining the effects of a change of poisson's ratio) mapped into a Fourier exponential transform space, a transition from the Kelvin to the Cerruti problem via the Boussinesq problem is achieved. An example illustrating in some detail the calculation of stress is added.
Solvability of a Stationary Problem on the Plane Motion of Two Viscous Incompressible Liquids with Non‐Compact Free Boundaries
Authors: Socolowsky J. 
Published: May 2007

AbstractA free boundary value problem for the motion of two heavy viscous, incompressible, capillary liquids, for instance in coating processes, is investigated. The flow domain and the two free interfaces are non‐compact and various corners occur. The existence and uniqueness of a generalized solution is proved in weighted Hölder‐spaces.
A Dual Perturbation Series Analysis of Homoclinic Bifurcation for Autonomous Systems
Authors: Smith P. , Yorke J. M. E. 
Published: May 2007

AbstractWe consider the perturbation of a Hamiltonian second‐order differential equation which has at least one homoclinic path. The perturbations take the form of damping (either linear or nonlinear) and self‐excitation as can occur typically in the equation for the van der Pol‐Duffing oscillator. The perturbation is a two‐stage process which involves first finding the perturbed homoclinic path, and then using this as the first approximation for neighbouring paths. By a process of matching solutions, leading term approximations for the periods and amplitudes of limit‐cycles which bifurcate internally and externally from the homoclinic path can be found. The symbolic computation system REDUCE has been used to facilitate integration of terms in the series.
On Density and Approximation Properties of Special Solutions of the Helmohltz Equation
Authors: Still G. 
Published: May 2007

AbstractWe consider eigenvalue problems for the Laplace operator on a region G. Especially if G is simply‐shaped, defect‐minimization methods with trial functions φ satisfying the Helmholtz equation Δφ + λφ = 0 may be suitable for the numerical solution of the problem. Such functions φ are given for example by the classical method of separation of variables. This paper is concerned with density and approximation properties of these special solutions of the Helmholtz equation with respect to the supremum‐norm.
On Convergence of Semidiscrete Ritz‐Galerkin Schemes Applied to the Boundary Control of Parabolic Equations with Non‐Linear Boundary Condition
Authors: Tröltzsch F. 
Published: May 2007

AbstractThe paper is concerned with Ritz‐Galerkin approximations of parabolic control problems, where the control is acting in a non‐linear boundary condition. At first the convergence of the Ritz‐Galerkin method for parabolic initial‐boundary value problems with non‐linear boundary condition containing “rough” boundary data is proved by semigroup techniques. Then this result is applied to show convergence of optimal values for approximated control problems.
On some Ramifications of the Center of Shear Problem
Authors: Reissner E. 
Published: May 2007

AbstractThis note generalizes an earlier analysis of the shear center and twist center problem within the framework of a suitably formulated mixed boundary value problem of three‐dimensional linear elasticity, by the consideration of more general boundary conditions than in [1], by a significant complementation of upper and lower bound formulas in [2], and by a method for the determination of the coordinates of these centers as functions of the applied loads for physically nonlinear elastic materials.
An Extension of Hamilton's Principle for Dissipative Continua
Authors: Albert H.‐F. 
Published: May 2007

AbstractHamilton's principle is derived for a continuum in the substantial (Lagrangian) description. There dissipative processes as well as initial and boundary conditions are incorporated. The Euler‐Lagrange equations of this principle are equivalent to the balances of mass, momentum, entropy, as well as these of certain extensive quantities not further specified, and constitutive relations for the dissipative fluxes as known from extended irreversible thermodynamics.
A New Approach to the Problem of Scattering of Water Waves by Vertical Barriers
Authors: Chakrabarti A. , Vijayabharathi L. 
Published: May 2007

AbstractUsing a modified Green's function technique the two well‐known basic problems of scattering of surface water waves by vertical barriers are reduced to the problem of solving a pair of uncoupled integral equations involving the “jump” and “sum” of the limiting values of the velocity potential on the two sides of the barriers in each case. These integral equations are then solved, in closed form, by the aid of an integral transform technique involving a general trigonometric kernel as applicable to the problems associated with a radiation condition.
Verallgemeinerte Diagonaldominanz bei nichtlinearen Funktionen. I
Authors: Frommer A. 
Published: May 2007

AbstractStreng oder irreduzibel diagonal dominante Matrizen und M‐Matrizen sind alle in der Klasse der verallgemeinert diagonal dominanten Matrizen enthalten. Mit dem Begriff der verallgemeinert diagonal dominanten Funktion stellen wir hier ein analoges Konzept für nichtlineare Funktionen vor. Spezialfälle sind u. a. die für Anwendungen besonders wichtigen streng diagonal dominanten nichtlinearen Funktionen und M‐Funktionen. Schwerpunkt dieser Arbeit bildet die Untersuchung charakteristischer Eigenschaften verallgemeinert diagonal dominanter Funktionen sowie deren Zusammenhänge mit anderen Funktionenklassen. In einer zweiten Arbeit werden wir dann zeigen, wie mit dem Konzept der nichtlinearen verallgemeinerten Diagonaldominanz diverse alte und mehrere neue Konvergenzresultate für nichtlineare (insbesondere asynchrone) Iterationsverfahren auf einheitliche Weise hergeleitet werden können.
An Approximation Scheme for the Three‐dimensional Scattered Wave and Its Propagating Far‐field Pattern in a Finite Depth Ocean
Authors: Gilbert R. P. , Xu Y. , Thejll P. 
Published: May 2007

AbstractThis paper is the first step in solving the submersible identification problem. An efficient numerical scheme is presented for computing the far field generated by scattering acoustic waves from an arbitrary shape in a wave guide. The inverse problem of determining the object from the far fields is discussed.
On the Dual Reciprocal Variational Approach to the Signorini‐Fichera Problem. Convex and Nonconvex Generalization
Authors: Panagiotopoulos P. D. , Haslinger J. 
Published: May 2007

AbstractThe aim of the present paper is the study of a new variational formulation for the Signorini‐Fichera problem. It is the dual reciprocal variational formulation which gives rise to an inequality constrained minimum problem only with respect to the unknown unilateral displacements. In the present paper the dual reciprocal variational problem is formulated for general unilateral boundary conditions derived from convex or nonconvex superpotentials. We obtain boundary variational or hemivariational inequalities and we study both for the coercive and the most important semicoercive case the existence and uniqueness (if any) of the solution. To this end a new form of Korn's inequality at the boundary is applied.
Symbolverarbeitung in der Mechanik — Zwei Beispiele
Authors: Kreuzer E. J. 
Published: May 2007

AbstractDie Symbolverarbeitung hat in der Mechanik bereits eine Reihe von Anwendungen gefunden; die Möglichkeiten des sympbolorientierten Rechnens mit Hilfe von Digitalrechnern sind aber heute noch längst nicht ausgeschöpft. In dieser Arbeit werden nach einigen grundlegenden Bemerkungen zu Symbolmanipulationsprogrammen zwei Beispiele aus der Mechanik herausgegriffen, bei denen die Symbolverarbeitung besonders vorteilhaft eingesetzt werden konnte: das Aufstellen von Bewegungsgleichungen und die Analyse nichtlinearer dynamischer Systeme.
Coupling of Elastic and Failure Properties of Initially Anisotropic Solids by Means of the Elliptic Paraboloid Failure Surface (EPFS) Criterion
Authors: Theocaris P. S. , Philippidis T. P. 
Published: May 2007

AbstractThe anisotropic failure criterion of the elliptic paraboloid failure surface is generally stated and appropriately formulated according to two postulates concerning safe loading paths. First the criterion is established for the generic anisotropic solid by assuming that it does not fail under hydrostatic compression and in the sequel a new hypothesis is conjectured according to which safe loading is the stress tensor whose associated strain tensor, in the context of Hookean elasticity, is spherical.
Ein Vergleich von Methoden zur Berechnung von thermisch bedingten mechanischen Spannungen unter Berücksichtigung der Erstarrung der Schmelze und der Bildung von Eigenspannungen
Authors: Hitzschke R.‐P. , Neundorf W. 
Published: May 2007

AbstractMit Bezug auf die thermische Erstarrung mit Phasenübergang flüssig/fest als eine technologische Variante der Glasverfestigung wird analysiert, wie Eigenverzerrungen beim Phasenübergang die Grundlage für Eigenspannungsquellen und somit von Eigenspannungen selber sind. Zwei vereinfachte Modelle und ihre numerische Behandlung werden vorgestellt.
Annular Liquid Jets: Formulation and Steady State Analysis
Authors: Ramos J. I. 
Published: May 2007

AbstractThe equations governing the fluid dynamics of long annular liquid, jets and long annular liquid membranes are derived by means of an integral formulation which is valid for Newtonian and non‐Newtonian Fluids. Analytical solutions for long, inviscid, steady state, annular liquid membranes are obtained in Eulerian coordinates as a function of the Froude and Weber numbers, nozzle exit angle, and pressure difference across the annular membrane. It is shown that the convergence length of the annular membrane increases as the Froude and Weber numbers, nozzle exit angle and pressure difference across the annular membrane are increased. The range of parameters for which the analytical solutions are valid is determined as a function of the Froude and Weber numbers for the case of zero nozzle exit angle and zero pressure difference. Analytical and numerical solutions for long, inviscid, steady state, annular liquid jets are also obtained and show that the convergence length decreases us the jet thickness‐to‐radius ratio at the nozzle exit is increased and increases at the Froude and Weber numbers, nozzle exit angle and pressure difference across the annular liquid jet are increased.
Verallgemeinerte Diagonaldominanz bei nichtlinearen Funktionen II: Anwendung auf asynchrone Iterationsverfahren und Beispiele
Authors: Frommer A. 
Published: May 2007

AbstractDer zentrale Satz dieser zweiten Arbeit zur nichtlinearen verallgemeinerten Diagonaldominanz gibt ein relativ weitreichendes Resultat über die Konvergenz asynchroner Iterationsverfahren zur Nullstellenbestimmung verallgemeinert diagonal dominanter Funktionen. Durch Spezialisierung in zwei Richtungen (Betrachtung spezieller Funktionenklassen und/oder spezieller Iterations‐verfahren) erhalten wir daraus eine Reihe bekannter und viele neue Konvergenzresultate für nichtlineare Iterationsverfahren. Darüber hinaus enthält die vorliegende Arbeit einige Beispiele für in Anwendungen auftretende verallgemeinert diagonal dominante Funktionen.
Semianalytic Solution of Boundary Value Problems by Using Approximated Operators
Authors: Gartland E. C. , Grossmann C. 
Published: May 2007

AbstractAdapted discretization methods can be obtained by a piecewise simplification of the differential operator and by exactly solving of the generated auxiliary problems. In the present paper we introduce a simple convergence analysis which rests on perturbed operators. Using special constructions of the perturbations the convergence of methods being based on piecewise truncated Taylor's expansions can be established. These methods are closely related to compact difference schemes.
A Sommerfeld‐Type Diffraction Problem with Second‐Order Boundary Conditions
Authors: Meister E. , Santos P. A. , Teixeira F. S. 
Published: May 2007

AbstractAn operator‐theoretic approach is used to study the problem of diffraction of time‐harmonic electromagnetic waves by a metalbacked dielectric half‐plane. The correspondent boundary value problem for the two dimensional Helmholtz equation is considered in a Sobolev space setting and is reduced to equivalent boundary integral equations of Wiener‐Hopf type in L+2(ℝ). An explicit analytical solution is obtained for the particular case of having the sam dielectric layer on both banks of the half‐plane.
ARMAX Modelling in Structural Dynamics – Approximations of the Differential Equations of Motion
Authors: Natke H. G. , Zamirowski M. 
Published: May 2007

AbstractARMAX models are popular in system identification. Spatial discretization of structural models leads to ordinary differential equations. The approximation of the differential quotients leads to ARX and ARMAX models of various orders. This approximation problem is discussed in the context of model order. Statistical studies due to a covariance equivalence of proposed models are investigated. Secondly, the inverse problem of identifying the physical parameters of the structural model from the ARMAX parameters within the approximation domain is also invesitgated.
Bewegungsgleichungen für Getriebesysteme
Authors: Brandl H. , Pfeiffer F. 
Published: May 2007

AbstractGetriebesysteme sind baumstrukturierte Mehrkörpersysteme mit linear Kinematik aber nichtlinearen Kraftkopplungen, die durch Spiel, Kupplungen und Lager entstehen können. Es wird eine allgemeine Theorie für derartige Systeme hergeleitet, die für beliebige Konfigurationen gilt und die an praktischen Beispielen erprobt ist.