Design and analysis of multistable curvilinear-fiber laminates based on continuous fiber 3D printing of thermosetting resin matrix

A novel manufacturing method for curvilinear-fiber multistable laminates using continuous fiber 3D printing technology is proposed, and a numerical and experimental investigation on the morphing behavior is performed. Traditional multistable laminates are developed from multiple straight-fiber laminates jointed or bolted together, but the designability of straight-fiber laminates is limited. More importantly, the fibers at the lap joints or bolted connection are discontinuous or fractured, which cause interfacial separation or stress concentration. Different from the traditional preparation process, continuous fiber 3D printing technology ensures the continuity of adjacent deformable elements and integrity of the structure, thereby reducing the interfacial separation or stress concentration of the laminates caused by fiber discontinuity or fracture, and providing the possibility for free variation of fiber angle. Continuous fiber 3D printing technology further improves the design space for com-posites instead of traditional straight-fiber laminate. In this paper, two different curvilinear-fiber multistable laminates are designed and prepared, and a finite element model was developed to predict the possible cured configurations and analysis the snap behavior. The numerical and experimental results show good agreement in stable configurations and snap process. Subsequently, a parametric study is carried out to explore the effect of different angle parameters on the snap process and stable configurations.