THERMAL RESIDUAL-STRESSES AND MECHANICAL-BEHAVIOR OF CAST SIC AL COMPOSITES

Thermal residual stresses developed during casting of SiC/aluminum com posites were studied as a function of cooling rate and volume fraction of fibers. Thermo-elastoplastic finite element analysis was used in t he investigation. The model accounts for the phase change of the matri x and the temperature-dependent material properties as the composite i s cooled from the liquidus temperature to room temperature. Further, t he effects of thermal residual stresses and fiber cross-sectional geom etry on the mechanical behavior of the composites were also studied. B ased on the study, it can be concluded that the matrix undergoes signi ficant plastic deformation during cool-down and the residual stress di stribution is a function of the cooling rate. In addition, the presenc e of thermally-induced residual stresses tends to decrease the aggrega te modulus of elasticity and increase the yield strength of the compos ites. The fiber cross-sectional geometry affects the constitutive resp onse of the composites in orientations transverse to the fiber axes.