Influence of Fiber Twisting Angle on the Fracture of Layers of Multilayer Composite Pressure Vessels

In the present study, the effect of twisting angle on the fracture of layers of multilayer composite pressure vessels was investigated. For this purpose, the cylindrical 8-layers vessel with twisting angles of [0°/90°/45°/-45°]s in the ABAQUS finite element software was simulated by varying the twisting angle of the middle layer fibers, and by applying the Tsai-Hill fracture criterion. The fracture of composite vessels was studied in terms of the Tsai-Hill index of failure (IF) as well as the stress- strain changes in those layers. The results showed that by changing the angle of the fibers respect to the vessel axis from 45° to 60°, the IF values in the 8-layers were reduced to less than one, indicating that the vessel with these twisting angles and with this thickness resists against to 200 Bar pressure. But, by changing the angle of fibers relative to the vessel axis from 60° to 67°, the IF values increased in the 90° layer to more than one, indicating that the vessel was on the boundary of failure. Therefore, it could be concluded that the best twisting angle of the fibers with this number of layers distribution was in the range of 54° to 60°.