A novel flaw alignment approach based on the analysis of bands of maximum strain using full-field deformation measurements

摘要

Standardized approaches for engineering critical assessment of defected structures contain procedures to evaluate the effect of interaction between multiple flaws. These procedures typically consist of two stages; alignment rules and combination rules. The former allows to categorize non-coplanar flaws as either aligned or non-aligned. Following, the latter classifies aligned flaws as interacting or non-interacting. Although these criteria are equally applied to different failure modes such as brittle fracture, elastic-plastic fracture and plastic collapse, most of them were initially developed based on linear elastic fracture mechanics for the sake of simplicity and conservativeness. Therefore, the application of these procedures might be questioned when applied to failure modes other than brittle fracture. This study attempts to develop an alternative methodology to evaluate alignment of non-coplanar side edge notches in tensile loaded specimens in presence of global plastic strains. Hereto, strain patterns are studied experimentally, based on full-field deformation measurements utilizing Digital Image Correlation (DIC). The results show that, in addition to crack driving force which represents a very local behaviour of defects, the global behaviour of the specimen in terms of strain patterns can be used to reveal interaction between non-co-planar flaws.