Finite element simulation of ring expansion and fragmentation: The capturing of length and time scales through cohesive models of fracture

摘要

The expanding ring test of Grady and Benson(1983) is taken as a convenient yet challenging validationproblem for assessing the fidelity of cohesive models insituations involving ductile dynamical fracture. Attention hasbeen restricted to 1100-0 aluminum samples. Fracture has beenmodelled by recourse to an irreversible cohesive law embeddedinto cohesive elements. The finite element model is three-dimensional and fully Lagrangian. In order to limit the extent ofdeformation-induced distortion, we resort to continuous adaptiveremeshing. The cohesive behavior of the material is assumed tobe rate independent and, consequently, all rate effects predicted bythe calculations are due to inertia and the rate dependency inplastic deformation. The numerical simulations are revealed to behighly predictive of a number of observed features, including: thenumber of dominant and arrested necks; the fragmentationpatterns; the dependence of the number of fragments and thefracture strain on the expansion speed; and the distribution offragment sizes at fixed expansion speed.