Peak normal traction given in units of stress per length.
The peak tensile normal traction t_{n,p} denotes the maximum normal traction in the linear elastic phase. The corresponding normal fracture opening w_{n,p} then comes out according to the Hooke's law. With the proceeding of delamination over this opening threshold, damage takes place so that the bearing loading of the material linearly drops down.
Used in no end-to-end test cases.