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 syst ems. Micrographic images are digitised and meshed for implementation into t he general purpose finite element code ADINA. The global cyclic response of the composite can be effectively modelled by using an appropriate constitu tive relationship to describe the cyclic elastic-plastic behaviour of the m atrix phase. The main advantage of the digital image based method is that t he actual microstructural details including particle size, shape, and distr ibution are inherently captured in the analysis. The predicted global stres s strain responses of aluminium alloy 6061-T0/Al2O3 particulate metal matri x composites under uniaxial and biaxial loading conditions (monotonic and c yclic) are found to correlate accurately with experimental results. When co mpared with predictions based on existing unit cell models, a noticeable im provement is observed. The effect of the representative length-scale (field of view) used in the analysis was found to be quite important in determini ng an accurate global response. A statistical analysis using uniformly deri ved lineal fraction measurements was also performed to demonstrate the corr elation between the particle morphology in a particular field of view and t he measured global response. Preliminary results indicate that this analysi s technique may provide a possible method for determining the appropriate l ength-scale for which global analysis applies. MST/4546 (C) 2000 IoM Commun ications Ltd.