Failure analysis of fiber reinforced composite thin-walled circular tubes under torsion load

The torsion buckling, failure load and failure modes of the carbon fiber reinforced polymer (CFRP) thin-walled circular tubes were tested and numerical simulated. Three failure modes of the circular tubes under torque were observed in the test, and the characteristics and mechanism of different failure modes were analyzed. Buckling and damage finite element models of the circular tubes were established by ABAQUS considering the factors such as initial imperfection and nonlinear buckling etc. of cylindrical shells. The results show that buckling could induce micro crack produce and propagation on the surface of the circular tubes, and it accelerates failure of the circular tubes. The interlaminar stress of the circular tubes under torque failure process is relatively small, and the interlaminar delamination is mainly caused by the sudden damage of the tube wall. The initial imperfection of the cylindrical shells has a great influence on the buckling and failure loads. The initial imperfection coefficient of the circular tube was determined by comparing the calculation results with test data in this paper, and the numerical simulation results of damage models and test data are consistent, which verifies the effectiveness of the finite element models.