Single Specimen Fracture Toughness Determination Procedure Using Instrumented Impact Test

摘要

The focus of the work is aimed at two scientific issues. The primary emphasis is directed to develop a method which enables the detection of ductile crack initiation, and hence the energy-based fracture toughness, by applying an optical crack opening displacement (COD) measuring device. It is claimed that the Double Displacement Ratio (DDR), i.e., the ratio of crack opening displacement vs. specimen displacement indicates the onset of ductile crack growth initiation in a way which is easy and reliable enough to apply in transition and upper shelf regions of a fracture toughness transition temperature curve. The method is extensively verified by experimental and analytical investigations, and compared with other single specimen methods used for dynamic fracture toughness determination. (Copyright (c) Technical Research Center of Finland 1993.)