Stress wave interference effects during fracture of silicon micromachined specimens

Abstract

We report on unique measurements of multiple microsecond-duration arrest periods during the propagation of high speed (>1 km s−1) cracks in micromachined single-crystal silicon specimens. These events were recorded electronically and in physical features remaining on the fracture plane. Using time-of-flight calculations, we have determined that these arrest patterns are due to the interference of boundary-reflected stress waves with the propagating crack tip. The specimen size, the measurement method, and the low acoustic attenuation in cyrstalline silicon facilitated the observation of these phenomena.