THERMAL RESIDUAL-STRESSES IN A SILICON-CARBIDE TITANIUM [0 90] LAMINATE/

The current work formulated a micromechanical analysis of a cross-ply laminate and calculated the thermal residual stress in a very thick [0 /90]ns silicon-carbide/titanium laminate. Results were also shown for a unidirectional laminate of the same material. Discrete fiber-matrix models assuming a rectangular array of fibers with a fiber volume frac tion of 32.5% and a three-dimensional, finite element analysis were us ed. Significant differences in the trends and magnitudes for the fiber , matrix, and interface stresses were calculated for the unidirectiona l and [0/90] models. Larger hoop stresses calculated for the [0/90] mo del indicate that it may be more susceptible to radial cracking when s ubjected to mechanical loading than the unidirectional model. The axia l stresses in the matrix were calculated to be slightly larger for the [0/90] model. The compressive axial stresses in the fiber were signif icantly larger in the [0/90] model. The presence of the cross-ply in t he [0/90] model reduced the constraint on the fiber, producing radial interface stresses that were less compressive, which could lead to ear lier failure of the fiber-matrix interface.