Seminar Announcement

Simulation of Dynamic Fracture using Cohesive Methods

Patrick A. Klein (Org. 8726)
Sandia National Labs

Thursday, June 6, 2002
Bldg. 905, Room 210
2:00 p.m. - 3:00 p.m.

Most conventional approaches to modeling fracture are based on small deformation constitutive models. These approaches are in contrast to the fact that extraordinarily large deformations inevitably occur in during fracture. Various cohesive models of fracture have emerged in recent years as modern approaches to numerical simulation of crack nucleation and growth without having to adopt an ad hoc fracture criterion. In comparison with conventional approaches, these models are physically more realistic in that they explicitly account for the fact that the cohesive strength and cohesive energy of solids are finite. We contrast two approaches for introducing cohesive behavior in fracture simulations. More conventionally, cohesive relations are imposed at the interfaces between elements within a finite element mesh. The assumption of this approach is that the surface constitutive laws acting between element boundaries determine the fracture behavior while the bulk constitutive models of the volume elements govern the deformation of the material otherwise. In contrast, the virtual-internal-bond model is a method by which cohesive behavior may be embedded directly into the continuum constitutive response by averaging cohesive interactions through a bond density function. Both approaches are capable of reproducing the dynamic crack tip instabilities observed in experimental studies of fast fracture. However, closer scrutiny of the approaches reveals that both suffer from pathological mesh dependencies that limit their predictive capability. These issues are explored within the context of our fracture modeling efforts in 8726.

This seminar is hosted by the Computational Sciences and Mathematics Research Department at Sandia National Labs in Livermore, CA. For more information on this or other events, visit http://csmr.ca.sandia.gov/news.html. Visitors from outside Sandia require advance arrangements in order to attend. For more information, please contact the CSMR office management assistant Doretha Smith at dahall@sandia.gov or (925) 294-4630.