An elastic interface model of the mixed bending-tension (MBT) test

The mixed bending-tension (MBT) test has been introduced by Macedo et al. to assess the interlaminar fracture toughness of laminates with low bending stiffness and strength in the longitudinal direction. In the experimental setup, the delaminated specimen is adhesively bonded to two pin-loaded metal beams. We have developed a mechanical model of the test, where the specimen is modelled as an assemblage of two beams connected by an elastic interface, while the metal beams are modelled as rigid beams. An analytical solution has been obtained by applying classical beam theory. Furthermore, to better describe the experimental results, we have developed also a cohesive zone model based on a bilinear traction-separation law.