Transverse tensile behavior of SiC-fiber/ Ti–6Al–4V composites—1. experimental results

Abstract

Under transverse tension (loads normal to the fiber axis), fiber/matrix debonding in fiber-reinforced titanium-matrix composites results in reductions in specimen stiffness and ultimate strength, and increased loading of the matrix. The interface structure and chemistry have a strong influence on the debond stress and therefore contribute significantly to the transverse composite behavior. In the present study a cruciform specimen geometry was employed over a range of specimen thicknesses to investigate the remote stress levels where debonding initiates in Ti–6Al–4V composites containing SCS-6 (C+Si coating), SCS-0 (no coating), and Trimarc 1 (carbon coating) SiC fibers. The different surface conditions of the fibers resulted in a range of remote interface debond stresses with SCS-0 being the strongest and Trimarc 1 being the weakest. Multiple-fiber, single-ply specimens of the three different fibers revealed that the remote debond stress did not vary for SCS-6 and Trimarc 1 compared to single-fiber tests, but were slightly lower for SCS-0. Part 2 of this study presents analytical and numerical modeling studies of the local stress state at the interface in relation to the applied stress, and discusses them with regard to these experimental results.