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

Abstract

Measurements of fatigue failure strength of laser-cracked fused silica in air at room temperature for different numbers of laser shots and laser fluences are presented. The failure-strength variability is found to be due mainly to the spectrum of crack depths. Agreement with theory suggests the incorporation of a residual term into the failure–strength equation. Due to its sign, the residual stress is of mouth-opening displacement nature at the crack. Analysis of the residual stress data shows a linear proportionality with crack depth, whereas the failure–strength is inversely proportional to the square root of the crack depth.