The root rotation in double cantilever beam and peel tests

In a peel test the plastic work has to be separated from the total work of fracture to obtain the cohesive energy. The root rotation determines the plastic work in a peel test and needs to be estimated accurately if the peel test is to be analysed successfully. Approximate solutions for the root rotation factor, based on the engineers’ theory of bending, are compared with finite element results to establish a reliable simple method of the estimation of the root rotation factor.