Crack Opening Displacements and Normal Strains in Centrally Notched Plates

摘要

Experimentally determined crack opening displacements of stationary and running cracks and of inclined stationary cracks in centrally notched plates are reported. The moire fringe technique was used for the determination of displacement fields in test specimen of magnesium, and 7075-T6 and 7178-T6 aluminum alloys. Experimentally determined crack opening displacements were compared with corresponding results based on theoretical models of Westergaard, Dugdale, Cragg, and Cragg-Dugdale. In addition normal strain fields derived from the moire fringe data were compared with static or dynamic strain fields of these theoretical models. The results of this investigation indicate that while the Dugdale crack is a fair model of a stationary crack in ductile materials, the Cragg crack appears to be a better representation of a running crack in the ductile material investigated. (Author)