THE USE OF THE LOCAL APPROACH FOR THE BRITTLE FRACTURE PREDICTION

摘要

The aim of the paper is in using the Beremin conception of local approach to fracture resistance assessment. The local approach uses internal microscale variables related to the material damage evolution in order to predict initiation of macroscale cracks in an elastic-plastic regime. This methodology was an invaluable complement to classical fracture mechanics, which is based on a single parameter for characterizing fracture, but not reproduces the transition behaviour satisfactory. The use of Weibull statistics for modelling of defect distribution over characteristic volume of material under a critical state of stress allows predict the probability of failure. Accepting these approaches to the analysis of local criteria for cleavage fracture the location parameter σ_u and shape parameter m were calculated using FEM for notched tensile bars having various type of geometry. The first one was tensile specimen with circumferential notch similar to Charpy V-notch specimen (CVN), the other three types were U shape with radii 1; 0.7; 0.2 mm.