Crack Propagation under the Pulsed Loads

Resumo

The article deals with the dynamic 2D problem of the theory of elasticity that considers a massive body with a semi-infinite plane crack, the faces of which are subjected to a normal pulsed tensile load symmetric to the crack. When studying the stress state ahead of the crack tip, the singular and regular terms have been found. They have been used to find the pre-fracture (incubation) period under the threshold loads. It has been shown that the regular term taking into account significantly affects the stress state, in particular, the incubation period. In the case of shock impulses above the threshold (overloads), the period of the crack tip movement with a variable speed (“breakthrough” of a crack) is considered as well as the pre-fracture period. To this end, the structural-time criterion for determining the incubation period is generalized to the case of the crack movement with a variable speed. A comparison of the calculated values of increasing the length of cracks after fracture caused by three shock impulses above the threshold with experimental data is made.