Modeling delamination as a strong discontinuity with the material point method

Abstract

Decohesion is an important failure mode associated with layered composite materials. Here, the energy implications of material softening are explored in a thermodynamic framework with the result that the dissipated energy (fracture energy) is greater than the plastic work of the traction on the failure surface. It is also argued that if the traction and continuum constitutive equations are solved simultaneously, the resulting algorithm is as simple as that for conventional plasticity. For numerical simulations, the material point method displays the attributes of no mesh deformation so that remeshing is not necessary and the continuous tracking of material points avoids the need for remapping history variables such as decohesion. Compatibility is invoked in a weak sense with the result that no special algorithms are needed for mesh realignment along crack surfaces or for double nodes. Example solutions exhibit no sensitivity of delamination propagation with mesh orientation.