MICROMECHANICAL MODELING OF DAMAGE GROWTH IN TITANIUM-BASED METAL-MATRIX COMPOSITES

The thermomechanical behavior of continuous-fiber reinforced titanium based metal-matrix composites (MMC) is studied using the finite elemen t method. Fiber and interface failures are modeled as discrete damage. The evolution of matrix failure is considered as continuum damage. A thermoviscoplastic unified state variable constitutive theory is emplo yed to capture inelastic and strain-rate sensitive behavior in the Tim etal(R)-21 s matrix. The SCS-6 fibers are modeled as thermoplastic and can fail at some prescribed plastic strain to failure. The effects of residual stresses generated during the consolidation process on the t ensile response of the composites are considered. Unidirectional and c ross-ply geometries are studied. Differences between the tensile respo nses in composites with perfectly bonded, weakly bonded and completely debonded fiber/matrix interfaces are discussed.