An Experimental Study of the Relation between Mode I Fracture Toughness, KIc, and Critical Energy Release Rate, GIc

Abstract

The construction of the relation between the critical energy release rate, (Formula presented.), and the mode I fracture toughness, (Formula presented.), is of great significance for understanding the fracture mechanism and facilitating its application in engineering. In this study, fracture experiments using NSCB and CCCD specimens were conducted. The effects of specimen sizes, loading rate and lithology on the relation between (Formula presented.) and (Formula presented.) were studied. (Formula presented.) was calculated by integrating the load–displacement curve according to Irwin’s approach. Based on the measured (Formula presented.) and (Formula presented.) of the rock specimens, a relation between (Formula presented.) and (Formula presented.) was found to be different from the classical formula under linear elasticity. It was found that both specimen size and loading rate do not influence this relation.