A mechanical model for mixed-mode delamination growth in composite laminates under cyclic compression

The paper presents a mechanical model for describing the buckling-driven mixed-mode delamination growth in composite laminates subjected to cyclic compressive loads. The laminate is modeled as the union of two sublaminates, partly bonded together by an elastic interface, i.e. by a continuous distribution of normal and tangential linear elastic springs. The model, already introduced in previous papers by the authors, allows for the determination of the explicit expressions of the normal and tangential interlaminar stresses, exerted between the sublaminates at the delamination front. Hence, the mode I and II contributions to the energy release rate and the mode-mixity angle can be deduced. Based on the above results, a modedependent fatigue growth law is applied. Thus, for any load level, predictions can be made on the number of cycles needed to grow a delamination to a given length. Results help to shed light on some experimentally observed phenomena of delamination growth and highlight the possibility of some very insidious failure modes.