PAMM
The paper deals with the effect of stress triaxiality on the inelastic behavior of aluminum alloys. The proposed continuum model takes into account stress‐triaxiality‐dependence of the yield condition as well as of the damage criterion and the fracture condition with different branches corresponding to different micro‐mechanisms. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The paper deals with generalized damage and failure criteria taking into account different mechanisms on the micro‐scale. Some micro‐mechanical numerical results are discussed and compared with the macroscopic analysis based on the continuum damage model. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In the product development of vehicle seat belt systems there is a strong need for the possibility of an isolated component testing that is comparable to real world car crashes. A test bench concept that is able to fulfill this requirement is presented. This test bench mainly consists of a highly dynamic actuator system for which a control scheme is presented. (© 2010 Wiley‐VCH Verlag GmbH & Co...
Composite systems consisting of glass fibres and epoxy matrix with interphases and interfaces will be considered in the modelling approach. The interphase forms the transition zone between the epoxy matrix and the glass fibre. The interface is the layer between the glass fibre and the surrounding interphase. The macroscopic strength of the composite material is intrinsically related to the bond strength...
In this paper the Aifantis' theory of elasticity for solids with double porosity is considered and the 2D boundary value problem (BVP) of static is investigated. The uniqueness theorem of the internal BVP is proved. The explicit solution the BVP is constructed in the form of absolutely and uniform convergent series for a circle. The numerical solution of the BVP for a circle is obtained. (© 2010 Wiley‐VCH...
The kinematic relationship between classical single crystal kinematics and geometrically necessary dislocations will be clarified by a demonstrative example. The starting point for the dynamics is the contribution of geometrically necessary dislocations to the free energy, which leads to a kinematic hardening law. A simple two‐dimensional shear example will be discussed. (© 2010 Wiley‐VCH Verlag GmbH...
In this work, the simulation of earings in cup drawing by means of a recently developed anisotropic combined hardening material model is discussed. The model represents a multiplicative formulation of anisotropic elastoplasticity in the finite strain regime with nonlinear kinematic and isotropic hardening. Plastic anisotropy is described by the use of second‐order structure tensors as additional arguments...
Two‐mechanism (or, generally, multi‐mechanism) models have been studied for the last twenty years. Besides one‐mechanism (or “Chaboche”) models, they are a useful tool for modelling inelastic behavior. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Neben mechanischen Beanspruchungen sind mikroelektronische Bauteile stets einer wechselnden thermischen Belastung ausgesetzt. Für die Gewährleistung zuverlässiger Fügeverbindungen ist daher die Kenntnis der materialspezifischen Kennwerte der Fügewerkstoffe in Abhängigkeit der Temperatur zwingend erforderlich. Die Nanoindentation erlaubt es aus einem Härteversuch Härte, Elastizitätsmodul und Fließgrenze...
When two elastic bodies slide against each other, contacting asperities carry tangential load. In the case of slow sliding, each asperity can show a stick‐slip‐like movement that can be modelled as an integrate‐and‐fire (IF) oscillator. Asperities influence each other by an elastic coupling which allows a globally synchronized state instead of local events. For two neighboured asperities, the dynamics...
Turbine blades are subjected to vibrations caused by static and dynamic loads. To avoid damage, the arising dynamic stresses can be reduced by generating friction contacts between the blades leading to additional damping. The resulting nonlinear equations of motion of the blade dynamics can be solved by the Multiharmonic Balance Method (MHBM), which is described in this paper. With the MHBM, it is...
The nonlinear analysis have been performed on the experimental data of a beam vibration composed of a wooden material MDF (Medium‐Density Fiberboard). Firstly, the beam was subjected to the harmonic excitation on the clamp with its first eigenfrequency. After reaching the eigenfrequency, the excitation was switched of and the velocity amplitudes were measured. To identify the frequencies and the damping...
Wälzlager besitzen abhängig von Drehwinkel und Belastung unterschiedliche Steifigkeit sowie Dämpfungs‐ und Reibverluste. Um das dynamische Verhalten und die Lebensdauer einer Maschine durch Simulationen zu beurteilen, werden daher die nichtlinearen Reaktionskräfte des Lagers als generisches Maschinenelement implementiert.
Um die Güte dieses Elements zu validieren werden verschiedene Messungen an einem...
In isothermal solid mechanics, the space and time domain need to be discretized. This paper presents an approach using high‐order finite elements based on Legendre polynomials for the spatial discretization and time‐adaptive diagonal‐implicit Runge‐Kutta methods for the temporal discretization. The superiority of this approach over a traditional one using linear shape functions for the space domain...
In an explicit time integration algorithm, the most time‐consuming part of an analysis is the computation of the internal nodal force vector. An implementation concept for element routines for volumetric shell so‐called Solid‐Shell ‐ elements based on the application of the symbolic programming tool ACEGEN, a plug‐in for the computer algebra software MATHEMATICA is presented. Symbolic implementation...
The computational modeling of failure mechanisms in solids due to fracture based on sharp crack discontinuities suffers in situations with complex crack topologies and for crack initiation in bodies free of defects. This drawback can be overcome by a diffusive crack modeling based on the introduction of a crack phase field. In [1,2], we developed a phase‐field‐model of brittle fracture, which is conceptually...
Stress singularities at two‐dimensional multi‐material‐junctions, consisting of dissimilar, homogeneous, isotropic and linear‐elastic wedges under a plane strain state are considered. The stresses formed at the vertex of this multi‐material composite situation are analyzed by complex variable method, based on a choice of the Kolosov‐potentials which are applicable in the vicinity of the vertex. The...
The mechanical buckling and postbuckling behaviour of a delaminated panel under uniaxial compression is investigated using a semi‐analytical geometrically nonlinear panel model. A Rayleigh‐Ritz procedure based on trigonometric displacement functions is used in conjunction with minimum energy principles to ascertain the mechanical response of the panels. The model includes the effect of delamination...