Finite element micromechanical modelling of yield and collapse behaviour of metal matrix composites

The initial yield and collapse behaviour of fibre reinforced metal matrix composites (MMCs) have been investigated using finite element micro-mechanical models. Initial yield occurs as the loading on the MMC is increased until the most heavily loaded point within the matrix reaches the yield stress. Collapse occurs when the MMC is unable to support a higher load. The results of this work show that loads to cause collapse of MMCs are higher than those to cause first yield, particularly when the effect of residual stress arising from manufacture is included in the analysis. Initial yield and collapse envelopes have been generated for a Silicon Carbide-Titanium MMC for biaxial and shear loading. These envelopes include the effect of residual stress and also various interface conditions between the fibre acid matrix: either perfectly bonded or de-bonded, with and without friction. An analytical micro-mechanical model has been developed using the method of cells to predict the collapse behaviour. The results of the analytical model compare reasonably well with those of the finite element method. Using the analytical model the effect of varying the fibre volume fraction on the collapse behaviour has been studied. (C) 2000 Elsevier Science Ltd. All rights reserved.