Arrest of Mode III Fast Fracture by a Transition From Elastic to Viscoplastic Material Properties

The transient problem of arrest of a rapidly propagating Mode III crack has been investigated for a crack which initially propagates in an elastic solid, and then enters a region of viscoplastic material properties. The transition to the viscoplastic behavior is modeled by a gradual process which starts at a certain time at which the constitutive relations change in a timewise manner from elastic to elastic-viscoplastic. Both deceleration and complete arrest of the crack have been treated. The solution has been obtained numerically by a finite-difference procedure. Arrest of a crack in a perfectly elastic material has been treated as a special case. Several field quantities such as the effective plastic strain, plastic work, total strain, and crack surface displacement have been computed, and their relation to arrest criteria have been explored.