Mechanical behavior of fibrous ceramic matrix composites under constant tensile load. Influence of fibre-matrix interface properties

摘要

uniaxial Young's modulus E and strain epsilon have been simultaneously measured at room temperature versus time in two kinds of 2D composites loaded in tension: SiC/SiC and C/SiC. E was determined using a specific ultrasonic pulse-echo technique working in samples subjected to a tensile stress. The two materials were found to exhibit differences in their behavior under constant loading. In SiC/SiC a significant decrease of E and an increase of epsilon have been observed versus time in sample loaded above the matrix cracking threshold; on the contrary there was no evolution of E in C/SiC. Thermal residual stress relaxation and fibre/matrix interfacial sliding were found to be responsible of these effects.