The transferability of fracture toughness characteristics from point a view of the integrity of components with defects

摘要

In this work, the use of the Weibull stress as a measure of the failure probability of cracked body is tested. Fracture of large engineering structures and conventional safety assessment and integrity of components and structures still remains a top field of research in the experimental and the theoretical fracture mechanics. Weibull stress seems to be a parameter for prediction of cleavage failure of cracked bodies and the study is focused to assess the effects of constraint loss on cleavage fracture toughness (J_c). To quantify the relative effects of constraint variation on the cleavage fracture toughness the form of the toughness-scaling model based on the Weibull stress σ_w is investigated. Local material parameters have been calculated arising from Beremin approach. It is based on weakest link assumption and incremental fracture probability, which depends not only on the maximum principal stress, but also on the equivalent plastic strain. Accepting this approach to the analysis of local criteria for cleavage fracture the location σ_u and shape parameters m were calculated using FEM for notched tensile bars having various type of geometry. The aim of the paper can be seen in fracture toughness correction from various specimen geometries to small scale yielding (SSY). The fracture resistance has been assessed using data from static tests of the bend specimens and from the axisymmetric notched tensile specimens. The standard finite element method package Abaqus was applied and the manganese cast steel considered for storage and transport container for spent nuclear fuel (SKODA) was selected as an experimental material.