Micromechanical experiments of interlaminar deformation and damage in quasi-isotropic thermoplastic composite laminates

In this paper, a system of micromechanical experiments is established combining microscopic moire interferometry of high spatial resolution with optical microscope. Under uniaxial tensile loading, the quantitative local-field of interlaminar displacements of the AS4/PEEK laminates has been measured. The pictures of in-situ interlaminar damage initiation and growth process have been simultaneously collected by the experimental system continuously. The major characteristic of interlaminar damage of the laminate under tensile loading is the group of matrix cracks in 90/90 plies, which are formed due to fiber- matrix interface debondings, and the number of cracks increases when the load increases. The u fields of interlaminar displacement of a matrix crack under certain loads are gained using the microscopic moire interferometry.