THREE-DIMENSIONAL FINITE ELEMENT MODELING OF RESIDUAL THERMAL STRESSES IN GRAPHITE/ALUMINUM COMPOSITES

摘要

Residual thermal stresses in graphite/aluminum fiber-reinforced metal-matrix composites is studied using three-dimensional finite element modeling and assuming the anisotropic thermal expansion coefficient of graphite fiber. The finite element results are compared with the two-cylinder model results of Vedula et al. and the experimental results of Tsai et al. During cooling from the processing temperature, the anisotropy of the graphite fiber results in the increase of the temperature range over which the elastic deformation of the matrix occurs. The effect of fiber volume fraction on the distribution of hoop and radial stresses at the fiber-matrix interface is also investigated. In the square and hexagonal array arrangements of fibers, the possible sites for the crack initiation are the points where the fiber-matrix interface intersects the lines joining the fiber center to its first nearest neighbors.