Enriched finite element method for 2-D and 3-D blunt crack problems in a viscoelastic medium

The analysis of two-dimensional and three-dimensional blunt crack problems in a linear viscoelastic medium is numerically investigated using the enriched finite element method. The enriched crack-tip elements are established by enriching the asymptotic displacement fields at the blunt crack front to the regular elements. The corresponding transition elements are formulated to eliminate displacement field incompatibility. The viscoelastic incremental formulations for the enriched finite element method in time domain are derived according to the Boltzmann superposition principle. The time-dependent deformations of crack are presented and the stress intensity factors are directly obtained from the enriched degree of freedoms. The numerical examples indicate that the enriched finite element method is extremely suitable for dealing with complicated blunt crack problems.