Specimen geometry effects on dynamic crack propagation

Dynamic crack propagation in PMMA was studied using the method of caustics in combination with a Cranz-Schardin type high-speed camera. Three different types of specimen geometries were employed to achieve the crack acceleration, deceleration and re-acceleration process in one fracture event. Dynamic stress intensity factor K_ID and the crack velocity were evaluated in the course of crack propagation to obtain the relationship between K_ID and the velocity The effect of crack acceleration and deceleration on the K _ID -velocity relations was examined.