Low-velocity impact damage in laminated composites materials

Low velocity impact damage in Carbon Fiber/PEEK crossply laminates is discussed in terms of experimental observations and prediction approach. The emphasis of the study is focused on defining the material parameters which may control the damage extension due transverse cracks and delamination. The residual stresses due to fabrication and the constraining effect induced by adjacent plies on the lamina in-situ strength are also analyzed. The extension of transverse cracks cannot be predicted by the strength of materials approach. The impact-induced delamination could be determined by the crack arrest concept in dynamic fracture mechanics. The delamination results from a Mode TI dominated unstable fracture, which occurred under a displacement-controlled condition and seems to be arrested at a constant interlaminar arrest-fracture-energy.