Improved analysis of the modified split-cantilever beam for mode-III fracture

A closed-form solution for the compliance and the energy release rate of the updated version of the mode-III split-cantilever beam specimen is developed incorporating linear beam theories. Apart from bending and shear of the specimen, the Saint-Venant and free torsion effects are considered. The analytical solution is verified by finite element calculations, leading to the conclusion that the compliance is very accurately determined, while the energy release rate differs only with 5% compared to the finite element calculations. Based on the finite element analysis the recommended crack length range is given in order to design a configuration that gives 98% mode-III contribution to the total energy release rate. At the final stage the analytical model is applied to reduce the data from experiments performed on delaminated glass/polyester composite beams. The results show that the closed-form solution is in a very good agreement compared to the results by experiments, although this requires very accurate measurements.