Singular plastic fields in non-associative pressure sensitive solids

Abstract Singular plastic ®elds at crack tips are investigated for a non-associative deformation theory modelling a Drucker± Prager material. Plane-strain mode-I eigensolutions are mapped over a range of material parameters along with a pure power law response. The material does not admit a strain energy function and the level of stress singularity is higher than the HRR values. The latter are recovered for associated models but, in general, the singularity reported here deviate from J-integral analysis with increasing non-associativity. Near tip pro®les are illustrated for a few representative cases, indicating an increasing sensitivity to non-associativity at higher levels of the hardening exponent