Analogy between crack initiation due to dynamic pulse load and mass-spring system failure: fracture delay effect

Abstract

In this short communication application of the incubation time fracture criterion (ITFC) for analysis of crack initiation under short pulse loading conditions is discussed. It is shown that the ITFC can be used to predict and investigate one of the key effects of the dynamic fracture – the fracture delay. The fracture delay phenomenon manifests itself when fracture occurs at a drop stage of local stress fields. In addition to this an analogy between crack instability under pulse loads and linear oscillator failure is drawn in the work. It is shown that the fracture process exhibits inertia when intensive loads are applied and a virtual oscillator with a particular eigen frequency can be formally attributed to a cracked sample. The applied theoretical models are calibrated against experimental data on crack onset under pulse loading conditions.