CRITICAL EXPERIMENTS, MEASUREMENTS AND ANALYSES TO ESTABLISH A CRACK ARREST METHODOLOGY FOR NUCLEAR PRESSURE VESSEL STEELS

Abstract

A two-dimensional, finite-difference, dynamic analysis of crack propagation and arrest is developed. The analysis has been applied to the wedge-loaded rectangular DCB specimen. Preliminary results of the two-dimensional analysis, particularly the crack velocity-arrest length relation, are very similar to those previously obtained with the one-dimensional treatment. Two critical tests of the dynamic/energy conservation analysis of crack arrest have been performed. Measurements of crack propagation and arrest in Homalite-100 performed at the University of Washington have been compared with one-dimensional calculations employing the KD-velocity dependence of this material measured independently at the University of Maryland. The calculations are in surprisingly good accord with the measurements of crack speed, arrest length and the local stress intensity. In addition, measurements of crack propagation and arrest in wedge- and machine-loaded, contoured DCB specimens of AISI 4340 are compared with calculations using the KD (V) previously derived from wedge-loaded rectangular DCB-test pieces. These experiments support the view that KD(V) is geometry and loading independent. Efforts to develop a testing procedure were centered on the LEFM size requirements for rectangular-DCB test pieces.