Abstract This work deals with numerical simulation of the mechanical behavior of materials composed of heterogeneous ductile microstructures using a multi-scale approach considering plasticity processes and phase debonding. Due to few studies about yield surfaces of metal matrix composites (MMC) with weak interfaces presented in the literature, the major goal of this work is to propose yield surfaces for metal matrix composites reinforced by rigid inclusions. The yield surfaces are obtained for Representative Volume Elements (RVEs) of materials presenting perfectly bonded inclusions and phase debonding in the interface zone. The matrix is considered an ideally plastic material governed by von Mises model, whereas the interface zone is modeled by means contact and fracture constitutive models incorporated in a proposed finite element. Also, RVEs containing different distributions and volume ratios of voids are analyzed. Considering the phase debonding, for compressive loadings the RVE behaves like RVE with perfectly bonded inclusions whereas for tension loadings the RVE presents a behavior quite similar to the one with voids. On the other hand, the concentration of voids in the RVE decreases its mechanical strength.

RESUMO O presente trabalho trata da simulação numérica do comportamento mecânico de microestruturas de Compósitos com Matriz Metálica (CMMs) utilizando uma proposta de modelo de homogeneização computacional baseada numa abordagem multi-escala. Na microestrutura do compósito, as inclusões são consideradas elásticas e o comportamento da matriz é governado pelo modelo de von Mises com endurecimento isotrópico. Um modelo de fratura coesiva é desenvolvido para simular a fase de descolamento da interface matriz/inclusão. Todo o estudo é baseado no conceito de Elemento de Volume Representativo (EVR), no qual podem ser empregados modelos constitutivos que levam em conta os fenômenos dissipativos de fissuração e plasticidade. Uma série de EVRs com diferentes composições de inclusões elásticas e submetidos a diferentes condições de restrição cinemática foram analisados. Também observou-se a sensibilidade paramétrica do modelo de fratura coesiva e a importância de se considerar a fase de descolamento matriz/inclusão no processo de ruptura da microestrutura. De modo geral, os resultados encontrados contribuem para a discussão acerca do emprego de modelos simples, em termos de formulação e identificação paramétrica, na modelagem da microestrutura de materiais heterogêneos, refletindo assim na acurácia de resultados qualitativos quanto ao seu comportamento macroscópico.

ABSTRACT This work deals with numerical simulation of the metal matrix composites (MMCs) microstructures mechanical behavior using a proposed computational homogenization modeling based on multi-scale approach. In the microstructure, elastic inclusions are considered and the matrix mechanical behavior is governed by a von Mises model with isotropic strain hardening. Besides, a cohesive fracture and contact model is developed in order to simulate the debonding phase in the matrix/inclusion interface. The study is based on the concept of Representative Volume Element (RVE), in which can be used constitutive models that take into account the dissipative phenomena of cracking and plasticity. A set of RVEs composed of different distributions of elastic inclusions and submitted to different kinematical restrictions are analyzed. Moreover, the parametric sensibility of the cohesive fracture model and the debonding interface relevance in the rupture processes of the microstructure are observed. In general, the results contribute to the discussion about the use of simple constitutive models, in their formulation and parametric identification, for modeling of the heterogeneous materials microstructures, leading to accurate qualitative results related to the macroscopic behavior.