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- Ermüdung (5)
- Schädigungsmechanik (5)
- Ti-MMC (5)
- Damage analysis (3)
- Isothermal fatigue (2)
- Metal matrix composites (2)
- Thermo-mechanical fatigue (2)
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Eingeladener Vortrag
- nein (1)
Indolizines, known as a useful class of fluorophores, were bridged yielding biindolizines. We intended to obtain long wavelength absorbing and emitting fluorescent systems suitable for fluorescence labeling of biomolecules. The influence of the different kinds of coupling on the absorption and fluorescence behaviour of the resulting biidolizines was studied. The new fluorophore systems were characterized spectroscopically by their absorption and emission maxima and their quantum yields.
The purpose of this work is modelling of the behaviour of a metal matrix (Ti-6242) that governs the nonlinear time-dependent response of the metal matrix composite (SiC/Ti-6242). For this purpose two different viscoplastic constitutive models are applied. First, it is the two-layer viscoplasticity model available in the finite element method (FEM)-based code ABAQUS. Second, it is the model of Chaboche implemented as a user material subroutine into another FEM-based code ANSYS and additionally into the package Mathematica. Parameters of both the models are obtained based on the available results of experimental tests carried out at different temperatures and strain rates. Utilisation of matrix models for simulation of the thermomechanical fatigue behaviour of the undamaged composite is discussed by a comparison with quasi-static tensile and high-temperature creep experimental tests.
Für viskoplastische Stoffgesetze wird das prinzipielle Verfahren der Identifikation von Materialmodell-Parametern für das Spannungs-Verformungs- und Versagens-Verhalten metallischer Werkstoffe am Beispiel von Hochtemperatur-Ermüdung aufgezeigt. Dies betrifft zum Einen die Verwendung geeigneter und auch möglichst weniger Experimente zur Hervorbringung der zu beschreibenden Phänomene des Werkstoffverhaltens und deren gezielte Auswertung sowie zum Anderen die physikalisch kontrollierte Führung einer numerischen Optimierung zur Ermittlung vertrauenswürdiger Materialparameterwerte. Diese Vorgehensweise wurde erfolgreich auf Warmarbeitsstähle sowie poly- und einkristalline Superlegierungen angewendet.
During hot extrusion of aluminium alloys, extrusion dies experience cyclic temperature changes as well as multiaxial loadings. To improve the service life of the dies, cleaner and high hot strength materials are designed as well as an optimised process control is performed. For the improvement of the process guiding and a comparison of lifetime behaviour of different hot work tool steels, modelling and simulation are appropriate means. The extrusion process has been simulated using the FE-program Deform to find the stress and temperature history at the inner diameter of the liner, i.e. the boundary conditions for the subsequent cyclic simulation of the container during service. Inelastic constitutive equations have been implemented into Abaqus Standard to describe strain hardening and time recovery effects. They include the Norton viscoplastic flow rule, thermo-mechanical isotropic hardening and two non-linear kinematic hardening laws. A damage-rate model predicts failure and thus the lifetime of the container. The procedure for the identification of material parameters for both the constitutive and the damage model is described in detail for the hot work tool steel Böhler W400 VMR (EN 1.2343).