Strength-based concurrent shape and fiber path optimization of continuous fiber composites

Abstract

This paper introduces a novel strength-based structural optimization technique capable of concurrent design of shape and fiber path in continuous fiber-reinforced composites. To this end, a higher order function, i.e., the level-set function, is employed to update both shape and fiber placement. The shape evolution relies on a shape sensitivity analysis based on the Tsai–Wu failure criterion. The fiber path evolution depends on the level-set function determined from the shape boundary. A scheme combining the classical level-set method using fixed mesh and a level-set-based mesh evolution method is developed to ensure the efficiency and accuracy of the process. A revision step over fiber orientations along the ridge of the level-set function is introduced to alleviate the local failure index singularity. Manufacturability of the design is further ensured by incorporating a thickness control term, avoiding the appearance of ultra-thin members in the optimized design. The developed scheme is applied to three benchmark examples, showing that the failure index concentration is largely reduced compared with the initial shape, the compliance-based optimized design, and the design with optimized shape but unidirectional fibers.