Design of a composite truncated elliptical rotary shell based on variable-angle trajectories

Abstract

Composite rotary shells are widely used in many industrial applications. Realising low defects, high placement efficiency, and uniform fibre coverage for producing composite rotary shells by the fibre placement process are critical design issues. In this study, a composite truncated elliptical rotary shell is used as an example to study a variable-angle fibre path planning method to meet composite rotary shell manufacturing requirements. The rotary shell is divided into a series of revolution surfaces using the equidistant offset method. Based on differential geometry, a theoretical equation of the initial path for the revolution surface is derived based on the gap constraint, and the curvature and outlines of the fibre placement path are calculated. With the boundary constraints considered, a search method for the start and end points of the fibre path is presented. When the initial path is rotated, a uniform fibre coverage pattern is obtained and simulated. In addition, a fibre path connect method is then proposed to reduce the fibre cutting number and further improve the placement efficiency. The two curvatures and fibre coverage for different process parameters are analysed and compared in detail. Finally, the mechanical properties of variable-stiffness composite truncated elliptical rotary shells under uniform internal pressure are simulated and analysed. The results show that the proposed fibre path planning method is reasonable and accurate, and the structure strength of the shell can be adjusted by changing path parameter N (fibre bundle number). The present method provides a useful tool for parametric design and low-cost rapid prototyping of composite rotary shells.