Combined Elastic-Plastic and Acoustic Emission Methods for the Evaluation of Tearing and Cleavage Crack Extension
SourceA synergism between the acoustic emission and fracture mechanics techniques to predict failure in laboratory specimens of different structural materials is discussed. Emphasis is placed on situations in which fracture occurs by a cleavage crack propagation or controlled by the slow growth to fracture of a single crack. Results obtained during the tests indicate that acoustic emission is capable of detecting the onset of flaw growth and provide a precursor of the immediacy of fracture in a variety of steel and aluminum alloys. A new J/Ji key resistance curve procedure is developed for the evaluation of ductile fracture toughness (JIc) and tearing modulus with a single small specimen. Moreover, a new acoustic emission rating parameter for predicting tearing instability of elastic-plastic crack growth is proposed and related to the tearing modulus parameter.