Constitutive Modelling of Spall Fracture

Abstract

Spall fracture (spallation) is a particular kind of dynamic fracture that results from the tension produced by the interaction of propagating waves of rarefaction. Such waves can be caused by the impact of a projectile (flyer) onto the surface of a structure (target) [1], the detonation of a high explosive in direct contact with the target [2], or by sudden deposition of an intense pulse of energy on the target surface [3]. More specifically, in the case of plate impact, the initial compressive stress wave travelling across the target reflects back at the free surface as a propagating decompression wave. A similar process, oppositely directed, occurs in the thinner flyer plate. The superposition of the reflected decompression wave fronts, if sufficient intensity and time duration, can cause partial or complete separation of the material along a plane perpendicular to the direction of the traveling wave fronts, cf. Figure 15.1, [4–6]. Spallation as a particular manifestation of dynamic fracture and fragmentation in general, has been the subject of considerable investigation, particularly at the Stanford Research Institute [7–13], and at the Sandia National Laboratories, [14–18]. Review articles on spall and dynamic fracture by Meyers and Aimone [19], and by Curran, Seaman and Shockey [20], provide access to much of the extensive literature on the subject.