Denting and fracture of sheet steel by blunt and sharp obstacles in glancing collisions

Abstract

The different types of denting, scoring and fracture that occur in “glancing collisions” between sheet steel and blunt or sharp obstacles, have been investigated. These collisions have a component of motion along the surface of the sheet or plating as well as perpendicular to it, and are to be distinguished from the usual sort of penetration/perforation problem. Crack initiation for blunt obstacles occurs by in-plane stretching and the biaxially dependent in-plane fracture strain pairs are well described by the fracture-forming limit diagram. Crack initiation for sharp obstacles is less easy to put in terms of critical strains, owing to the highly localised deformation regions. For both types of obstacle, crack propagation is modelled successfully using rigid-plastic fracture mechanics. Applications to ship grounding, motor vehicle crashworthiness, etc., are discussed.