Lifetime prediction of laser-precracked fused silica subjected to subsequent cyclic laser pulses

Measurements of fatigue failure strength of laser-cracked fused silica in a ir at room temperature for different numbers of laser shots and laser fluen ces are presented. Thr failure-strength variability is found to be due main ly to the spectrum of crack depths. Agreement with theory suggests the inco rporation of a residual term into the failure-strength equation. Due to its sign, the residual stress is of mouth-opening displacement nature at the c rack. Analysis of the residual stress data shows a linear proportionality w ith crack depth, whereas the failure-strength is inversely proportional to the square root of the crack depth.