Instrumentation for Full Field Deformation Measurement with Nano-Second Resolution

Abstract

Abstract : The accurate evaluation of the dynamic fracture toughness of advanced materials is becoming increasingly important. Under dynamic fracture, material at the crack tip is strained suddenly, and if is rate sensitive, may offer more resistance to fracture than at quasi-static strain rates. High stain rate fracture testing is of interest because many structural components are subject to high loading rates in service or must survive high loading rates during accident conditions. Thus, these components must be designed against crack initiation under high loading rates or to arrest a rapidly propagating crack. The fracture toughness of a material loaded suddenly is generally higher than when the load is applied quasi-statically; therefore, dynamic toughness is an effective design parameters. While there exists standardized method for determining the fracture toughness parameters K(IC) and J(IC) under quasi-static loading, to date, a unified view on the best measurement procedure to determine the dynamic fracture toughness of advanced materials has not been achieved. Hence, researchers still need to identify a simple and reliable experimental method capable of providing accurate dynamic fracture toughness measurements. Further understanding of the failure phenomena (such as crack propagation, material instabilities, etc.) in advanced layered and nano-materials require the development of novel experimental techniques. The motivation of the present investigation is to establish a reliable experimental/computational procedure to obtain both accurate dynamic fracture toughness and crack dynamic propagation parameters.