Applications of a 2-D moving finite element formulation to elastic/viscoplastic dynamic fracture analysis

Current efforts to resolve the near crack tip fields in elastic/viscoplastic materials using finite element methods have failed to achieve a finite non-zero energy flow to the crack tip. Motivated by these difficulties, a moving element formulation incorporating a variable order singular element to enhance the local crack tip description is presented. The moving mesh zone is embedded in a finite global mesh to provide a functional tool for the analysis of dynamic crack growth experiments. The necessary elasto-dynamic formulations have been previously implemented in a transient finite element program DYNCRACK and checked against known analytical solutions. These results have encouraged an attempt to include Perzyna's elastic-viscoplastic model in the formulation. However, the introduction of non-linear history dependent material behavior into a moving element scheme requires a method to interpolate related field quantities to new Gauss point positions for each time step. The following summary of numerical procedures outlines the approach taken to develop a transient elastic/viscoplastic moving finite element formulation. Results for a standard test problem are then compared to those obtained using the nodal relaxation technique. Further development of the code is discussed with respect to applications to dynamic fracture experiments.