Analysis of biaxial loading effect on fracture toughness of reactor pressure vessel steels

The local stress-strain state (SSS) near the crack tip and its connection with the crack tip opening displacement and J-integral under biaxial loading have been studied by finite element methods in elastic-plastic finite strain statement. Numerical investigations have been performed for various crack lengths and two types of biaxial loading (tension and bending) under conditions of small- and large-scale yielding. To predict the biaxial loading effect on cleavage fracture toughness, the procedure has been elaborated, this being based on the revealed regularities for SSS near the crack tip under biaxial loading and brittle fracture criterion proposed earlier. Prediction of the biaxial loading effect on cleavage fracture toughness has been performed as applied to reactor pressure vessel steel. The calculated results have been compared with available experimental data. Alternative approaches for prediction of the biaxial loading effect on fracture toughness have been discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.