ANALYSIS OF A [0-DEGREES 90-DEGREES] METAL-MATRIX COMPOSITE UNDER THERMOMECHANICAL FATIGUE LOADING/

The response of a [0-degrees/90-degrees] composite thermomechanical fa tigue (TMF) loading is computed using a completely strain-coupled anal ysis via the finite element method. Calculations are made for in-phase and out-of-phase TMF conditions assuming either a perfect or an imper fect fiber-matrix interface. In addition, a simplified composites anal ysis (S-CAN) procedure is used to determine the response assuming no l ateral strain coupling between the [0-degrees] and [90-degrees] plies. Comparison of the results from the two analyses indicates that the un coupled analysis provides accurate strains and fiber stresses in the l ongitudinal direction, but individual ply (average) stresses are not a s well predicted. The complete three-dimensional finite element comput ations indicate that results obtained using an imperfect interface pro vide better correlation with experimental data than those obtained ass uming perfect bonding. The micromechanical stresses developed at the f iber-matrix interface are used to identify the critical locations wher e matrix failure is expected to occur. These locations are validated t o a reasonable degree with experimental observations.