Title: "MICROMECHANICAL MODELLING OF METAL MATRIX COMPOSITES WITH CONTINUOUS FIBRES"
Author: ALFREDO GERARDO RÍOS NOGUÉS
Date: 2010-02-12
Director: Dr. Antonio Martín Meizoso
Abstract:
The thesis is dedicated to the study of the mechanical behaviour of copper (and copper alloys) matrix composites (reinforced with continuous fibres) when subjected to complex loading: thermal and mechanical loads. The analysis is focused on the micromechanical modelling to estimate the thermo-mechanical behaviour of the material composite. Finite element method has been used in the micromechanical modelling.
The fibre/matrix interface plays an important role in the mechanical behaviour. Thus, cohesive elements have been used to model the fibre/matrix interface effect on the composites. Push-out data, provided by the Max-Planck Institute for Plasma Physics, were used to compute the parameters values (debond stress, adhesion energy), which have been used in the cohesive elements of ABAQUS® software. Additionally, copper undergoes creep phenomenon at high temperatures. Hence, a power law creep is used in the simulations to obtain a more realistic model.
Other important influence on the composite behaviour is the inelastic behaviour of the matrix. The viscoplasticity model is very important tool to describe the thermo-mechanical behaviour of materials subjected to complex loading, i.e. cyclic loading. For this reason, both Chaboches’s model and a unified viscoplastic model, have been used to study the mechanical behaviour of the pure copper (and copper alloy) matrix, reinforced with SiC-fibres, when undergo cyclic loading, at different temperatures.
The unified viscoplastic model presented is based on the work of J. L. Chaboche, which is developed on the combination of kinematic hardening and isotropic hardening. The capability of the unified model proposed to describe the cyclic hardening behaviour of pure copper and CuCrZr alloy is shown in this work.
Good agreement between the simulation and experimental results are found using the unified viscoplastic model, for pure copper and alloy copper at different temperatures, which support the capability of the model.
The unified viscoplastic model is extend to the simulation of a crossply composite (with copper matrix) to predict the behaviour at different temperatures, as well as for a random fibre distribution.
