Ultimate bearing capacity and fatigue life analysis of marine sandwich composite bolted connection structure: Fatigue test and numerical simulation

•The simulation method of progressive failure of complex composite structures is improved and renewed.•The improved fatigue life prediction process of sandwich composite structure is put forward.•The ultimate bearing capacity and fatigue life of sandwich composite-bolt connection structures are predicted and verified. Because of the great difference in performance between component materials, there are some problems in sandwich composite structures, such as complex fatigue failure mode and difficult observation of internal damage. The numerical simulation method of fatigue can effectively simulate the whole process of fatigue failure. At present, the fatigue failure prediction methods of reinforced fiber laminates and interlayer interfaces are effectively analyzed, but there is no relevant numerical simulation method that can consider the fatigue failure of core materials. Based on the fatigue test data of foam core materials, an improved fatigue life prediction method of foam core material with principal stress and Tresca stress as basic parameters is proposed, and a progressive failure fatigue analysis method of foam sandwich composite structure is formed by combining the stiffness/strength degradation model of fiber reinforced laminates and Shokrieh fatigue failure criterion. Based on the finite element calculation software ABAQUS, the corresponding UMAT subroutine is compiled and the fatigue life and damage mode prediction of the sandwich composite bolted connection structure are verified. Compared with the experimental results, it can be found that the proposed finite element fatigue analysis method has high calculation accuracy and can be used to guide the anti-fatigue design and optimization of sandwich composite structures.