Micromechanics of inclusion-reinforced composites in elasto-plasticity and elasto-viscoplasticity : modeling and computation/
Year: 2006
Type: dissertation
Abstract: In this thesis, we propose some innovative developments for the implementation \nof mean-field homogenization schemes adapted to the prediction of the \nbehavior of elasto-plastic and elasto-viscoplastic composites.\nFor elasto-plastic materials, the local constitutive laws written in a rate form \nare linearized incrementally over several time-steps so that homogenization \nschemes developed in the context of linear elasticity can apply over each time \ninterval. Since the original implementation gave too stiff predictions, we \npropose different stiffness reductions for the matrix tangent operator and study \ntheoretically and numerically the influence on the final macroscopic prediction. \nDefinition of the per phase reference state in also studied and linked to the \nfields heterogeneity effect. Predictions thus obtained are confronted with \nthose of a secant (or total) formulation of the constitutive laws. \nFor elasto-viscoplastic composites, we use the affine formulation which reduces \nthe constitutive laws to fictitious linear thermo-elastic relations in the Laplace \ndomain where the homogenization can apply. Our main contribution is a full \ntreatment of internal variables in the linearization procedure. This enables to \ndeal with realistic constitutive behaviors and general loading histories. We \nillustrate the influence of viscous effects under various loading conditions and \nstudy the accuracy of the method with respect to the loading rate. \nFor both classes of composites, numerous predictions obtained by mean-field \nhomogenization schemes are confronted against those of three-dimensional finite element simulations and experimental results. For a wide range of materials and loading conditions, a good agreement at the macroscopic level between our predictions and the reference results is observed.
Author: Olivier Piérard
Language: English
Topic: Composite Material Mechanics
Subfield: Mechanics of Materials
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1734574656