Analysis of Al/Al2O3 metal matrix composites under biaxial cyclic loading using a digital image based finite element method

This paper examines the use of a two-dimensional digital image based finite element method to predict the global behaviour of multiphase material systems. Micrographic images are digitised and meshed for implementation into the general purpose finite element code ADINA. The global cyclic response of the composite can be effectively modelled by using an appropriate constitutive relationship to describe the cyclic elastic-plastic behaviour of the matrix phase. The main advantage of the digital image based method is that the actual microstructural details including particle size, shape, and distribution are inherently captured in the analysis. The predicted global stress strain responses of aluminium alloy 6061-T0/Al2O3 particulate metal matrix composites under uniaxial and biaxial loading conditions (monotonic and cyclic) are found to correlate accurately with experimental results. When compared with predictions based on existing unit cell models, a noticeable improvement is observed. The effect of the representative length-scale (field of view) used in the analysis was found to be quite important in determining an accurate global response. A statistical analysis using uniformly derived lineal fraction measurements was also performed to demonstrate the correlation between the particle morphology in a particular field of view and the measured global response. Preliminary results indicate that this analysis technique may provide a possible method for determining the appropriate length-scale for which global analysis applies. MST/4546 (C) 2000 IoM Communications Ltd.