On the energetics of dynamic cohesive crack formation

Abstract

AbstractDynamic fracture under static loading, as it takes place in the absence of a perfect pre‐crack, is studied from simple 1D and 2D examples. Special emphasis is placed on the cohesive fracture energy which gives rise to a finite duration of the fracture process and – in conjunction with the material's tensile strength – introduces a material specific length scale.In case of the 2D problem (plate with hole under remote tension/compression), a (quasi‐)spontaneous formation of the finite crack increment, as predicted by FFM, can only be identified for compressive loading (stable crack growth). For tensile loading (unstable crack growth), a non‐monotonic dependence of the crack velocity on the hole radius was observed, attributed to a competition between the effects of crack initiation under higher overall stress for smaller holes and a comparatively larger process zone w.r.t. the hole radius.