IA»caIization analysis under dynamic loading

ABSTRACT: A finite element method proposed by Ortiz et a/. (1987) is used to study shear band formation in rate dependent and rate independent pressure eensitive solids under dynamic loading. Under these conditions, shear bands are observed to propagate in an irregular fashion in time and space. In particular, the development of multiple shear bands appears to be a prevalent mechanism of deformation at sufficiently high impact velocities. 1. IntroductioD. Localization of deformation into bands of intense shearing occurs in a wide variety of solids: ductile single crystals, Chang and Asaro (1981), polycrystalline structural metals, Marchand and Duffy (1988), saturated clays, Vardoulakis (1979), rocks, \'Vaversile and Brace (1971) and concrete, van Mier (1984). Localization processes furnish a mechanism for the local accumulation of large plastic deformations, and may be a precursor to ductile shear failure, Muchand and Duffy (1988). The overall response of a solid is sharply in8uenced by the emerging shear bands. A case in point is the structural 8Ort.ening of sand specimens in plane strain biaxial compression, where the apparent ICl6s of bearing capacity of the sample is a direct consequence of shear banding, Leroy and Ortiz (1989a). The physical mechanisms which trigger localization vary widely between materiala and loadin