Surface energy for creation of multiple curved cracks in rubbery materials

A fracture parameter M_c is proposed for evaluation of the surface energy associated with the creation of multiple curved cracks in 2D rubbery solids under the action of large deformation. Based on the concept of the M-integral, the parameter is developed by performing the integration along a closed contour enclosing all the cracks and with respect to a reference coordinate system originated at the geometric center of all the crack tips, The integration is shown to be path-independent so that the complicated singular stress field in the near-tip areas need not be involved in the calculation. It is thus suggested that M_c be possibly used as a fracture parameter for describing the degradation of material and/or structural integrity caused by irreversible evolution of multiple curved cracks in a rubbery media.