Development of Damage in Low-Carbon Steel under Mode I and Mode II Loading Conditions

摘要

The geometry of plastic deformation localization zones in low-carbon steel specimens under mode II and I conditions is estimated using replicas, and the evolution of microcrack patterns in these zones is studied by acoustic emission. It is shown that, under mode II loading, the plastic deformation zone area decreases and an additional system of microcracks appears; as a result, the number of microcracks and the number of acoustic emission signals increase. The following localized fracture criteria are discussed: the concentration criterion and parameters b_c and b_(AE) of the length and amplitude distributions of microcracks and acoustic signals, respectively. These parameters are used to characterize and predict the fracture probability.