Strain fields and damage around notches in ceramic-matrix composites

Strain development in several notched ceramic-matrix composites (CMCs) has been monitored over a broad range of load. This was achieved by using phase-shifting moiré interferometry, which provides a map of the surface strains. A sequence of fringe patterns was used to chart the evolution of strain redistribution as a function of load. The ensuing strains were related to the micromechanical damage mechanisms. Stress concentrations were estimated from the strains by using stress/strain curves. Implications for the notch sensitivity of CMCs are discussed.