AN EXPERIMENTAL-STUDY OF RESIDUAL FIBER STRAINS IN TI-15-3 CONTINUOUSFIBER COMPOSITES

A simplified experimental technique to determine the axial fiber resid ual strain in continuously-reinforced metal matrix composites is descr ibed. The residual fiber strains in two Ti-15V-3Cr-3Al-3Sn/SiC metal m atrix composites have been measured with this technique. Residual fibe r strains on the order of 0.2% are measured in the as-processed condit ion, and the residual stresses approach zero after testing the composi te in tension to failure at room temperature. A conceptual description of the effect of tensile testing on the residual stresses is provided . The experimental results are consistent with predictions based on a concentric cylinder iso-strain analysis of thermal strains. Measuremen t errors result in a residual fiber strain error that is typically les s than +/-0.05%. Periodic fiber bending induced by cross-weave fibers is also analyzed, and may contribute significantly to measurement erro rs.