J-integral

Summary

The J-integral is a contour integral around the tip of a crack that measures the energy flowing into the crack tip. For a hyperelastic material, its value does not depend on the contour. So it can be computed far from the tip, where the fields are easy to obtain. For a linear elastic body it equals the energy release rate. It is used as a fracture parameter in elastic–plastic fracture mechanics, where the stress intensity factor no longer applies.