AN ANALYSIS OF RESIDUAL-STRESS FORMATION IN WHISKER-REINFORCED AL-SIC COMPOSITES

The effects of fiber spacing, volume fraction and aspect ratio on the residual stresses in metal-matrix composites are analyzed numerically. The composite is modeled as a periodic array of cylindrical cells, each consisting of the matrix alloy with a whisker embedded in the ceter. Account is taken of thermoelasticity both in the fiber and in the matrix and of temperature-dependent plasticity in the aluminum matrix. A general formulation, valid for finite strains and rotations, is discussed. Quenching is simulated by imposing a temperature history obtained from a macroscopic solution of the heat equation for a cylindrical bar to the surface of a cell. The resulting residual stress fields are calculated. The results show that the side-to-side spacing of fibers is the most important microstructural parameter affecting the distribution of residual stress and plastic deformation in the matrix. The overall level of plastic deformation in the matrix, measured by the volume average of effective plastic strain, depends primarily on fiber volume fraction. The fiber aspect ratio has little effect, apparently because the residual fields become essentially independent of axial position a short distance from the fiber corner. © 1990.