Progressive fatigue damage analysis of composite bolted joint using equivalent stress model.

Composite bolted joints are quite necessary for composite structures connection, which has become the main limit for the use of composites in main load-bearing structures. In this article, a fatigue model of composite bolted joint based on equivalent stress is established by programming in ABAQUS USDFLD subroutine to simulate the progressive failure of composite bolted joints. By introducing three-dimensional Tsai-Hill static failure criterion, equivalent stress is calculated for investigating effects of multiaxial stress on fatigue life. In the subroutine of progressive failure for fatigue model, fatigue life of composite bolted joint and damage state of elements that are meshed in the process of modelling are connected by defining field variable. Different fatigue modes are predicted here by changing stress amplitude and ratio loading, in which simulation results agree well with that obtained in corresponding experiments.