Measurement of interface cohesive stresses and strains evolutions with combined mixed mode crack propagation test and Backface Strain Monitoring measurements

A Mixed Mode Bending (MMB) test is used to study the fracture process of an adhesively bonded specimen. Simple Beam analysis is proposed to estimate the Strain Energy Released Rate (SERR) from the evolution of specimen compliance. The effect of interface compliance on the process zone extension and specimen deformation is studied. Additionally, the Backface Strain Monitoring (BSM) technique is used to probe the peel and shear cohesive stresses along the bondline. With a simple analysis, a systematic procedure is proposed to evaluate the cohesive stresses as well as the peel and shear strain evolutions in the vicinity of the crack tip position during crack propagation experiment under mixed mode conditions.