TENSILE DAMAGE IN A SYMMETRICAL [0 90](2S) SILICON-CARBIDE FIBER-REINFORCED TITANIUM-MATRIX COMPOSITE/

The results of a detailed study of the effects of composite microstruc ture on the micromechanisms of tensile damage in a symmetric [0/90](2s ) Ti-15Al-3Cr-3Al-3Sn (Ti-15-3)/SiC (SCS-6) composite are presented. M atrix microstructure is controlled by heat treatment, which is used to produce metastable beta or Widmanstatten alpha + beta microstructures . The sequence of damage initiation and evolution at room temperature is identified using ex situ scanning electron microscopy (SEM) during incremental monotonic loading to failure. Damage mechanisms are also s tudied using non-destructive acoustic emission (AE) techniques, and ma trix hardening is characterized using matrix micro-hardness measuremen ts within individual plies. Idealized and actual microstructure-based finite-element models are used to rationalize the observed tendency of damage to propagate from the outer plies to the inner plies. The pape r highlights the importance of simplified micromechanical models in th e development of a fundamental understanding of the effects of composi te architecture on damage initiation phenomena. (C) 1998 Elsevier Scie nce Ltd, All rights reserved.