Fatigue-driven failure criterion for progressive damage modelling and fatigue life prediction of composite structures

This paper attempts to assess fatigue lifetime of full-scale composite cabin by using experimental and numerical methods. With due consideration of multiaxial stress state and stress ratio effect, the governing equation for multiaxial fatigue-induced residual strength at an arbitrary stress ratio was derived. Based on multiaxial fatigue-induced residual strength concept, new fatigue-driven failure criterion was devised for progressive damage modelling and fatigue life prediction of composite structures. Quasi-static and step constant-amplitude cyclic loading tests were respectively performed to measure the load versus strain curves and to determine fatigue life and failure mode of full-scale composite cabins. It is shown from experimental observations that fatigue damage first appeared at upper left fillet of cutout, and then propagated from upper left fillet to the nearby countersunk hole, which was followed by the propagation along the circumference direction of cylinder until final failure. A progressive damage model based on fatigue-driven failure criterion was generated for damage mechanism modelling and fatigue life prediction of composite cabin, and the numerical results correlate well with the experimental findings, demonstrating the practical and effective use of proposed failure criterion.