Application of Gurson Void Growth Model to Dynamic Fracture

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Strain localization is usually considered to be the precursor of ductile failure, and, beginning with Considere (1885), a great deal of effort has been directed towards determining the plastic instability point that precedes such well-known phenomena as necking, shear band formation and crack growth. The work of Hutchinson and Neale (1977) is one of the more recent examples of this work. However, at the microscopic level the nucleation, growth and coalescence of voids is generally accepted as an important mechanism in the ductile failure process. In a recent paper Chu and Needleman (1980) coupled the work of Hutchinson and Neale with the void growth continuum theory of Gurson (1977) to determine forming-limit diagrams for biaxial stretched sheets. In dynamic fracture the void growth concept may be even more important in that failure often occurs with no well defined strain localization. The spallation of thick plates under impact conditions is an example. In a study on the inertia effects on ductile failure Fyfe and Rajendran (1980) found that plastic instability is inhibited by inertia effects to the extent that classical plastic instability criteria under high strain-rate loading may of necessity require redefinition.