TRANSVERSE TENSILE BEHAVIOR OF SIC-FIBER TI-6A1-4V COMPOSITES - 1 - EXPERIMENTAL RESULTS/

Under transverse tension (loads normal to the fiber axis), fiber/matri x 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 st rong influence on the debond stress and therefore contribute significa ntly to the transverse composite behavior. In the present study a cruc iform specimen geometry was employed over a range of specimen thicknes ses to investigate the remote stress levels where debonding initiates in Ti-6Al-4V composites containing SCS-6 (C+Si coating), SCS-0 (no coa ting), and Trimarc I (carbon coating) SiC fibers. The different surfac e conditions of the fibers resulted in a range of remote interface deb ond stresses with SCS-0 being the strongest and Trimarc I being the we akest. Multiple-fiber, single-ply specimens of the three different fib ers revealed that the remote debond stress did not vary for SCS-6 and Trimarc I 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. Published by Elsevier Science Ltd.