Burst Pressure Prediction and Structure Reliability Analysis of Composite Overwrapped Cylinder

Based on strength design for thin-walled isotropic cylinders and mechanical properties for the composite material, the equation to predict burst pressure of the composite overwrapped cylinder is established. Based on the equation, a structure reliability model is proposed to estimate the reliability of composite overwrapped cylinder by the advanced first order and second moment (AFOSM) method. The layer thicknesses, spiral winding layer angles, and the internal pressure are treated as random variables which obey normal distribution. Results shows that, the reliability of composite cylinders is reduced with the thickness of winding layers decreasing, and the thickness of loop winding layers plays the leading role on the reliability analysis. When the composite cylinder is operated in a low-level pressure, the reliability is not sensitive to the variation of the angle of spiral winding layers. And there will be a superior reliability, when the angle of spiral winding layers is within a certain range. Reducing variance of random variables is feasible to improve the structure reliability. The research also employs a reliability-based optimal design in the perspective of thickness and angles of composite winding layers. The strength of the optimized cylinder has been raised by 0.7% on the premise of cost saving and weight loss.