Controllable deformation design for 4D-printed active composite structure: Optimization, simulation, and experimental verification

Through integrating active composites and 4D printing techniques, active composites can achieve the predesigned complex deformations. However, the tremendous design space of multiple materials brings the challenges of finding the optimum material distributions accurately, and the consistencies between simulated optimum results and actual experimental structures. Therefore, the controllable deformation design framework is proposed to guide the inverse design of 4D-printed active composite structure. The material properties of polylactic acid (PLA) and thermoplastic polyurethane (TPU) are tested and integrated into forward deformation analysis to improve the prediction accuracy of finite element analysis (FEA). An optimization integration framework with genetic algorithm is developed to optimize the material distribution and external displacement simultaneously to achieve the target deformation. Several voxelized beams and flower structures are used as engineering cases. The simulated and experimental deformation shapes and recovery shapes for the optimum structures are consistent with the target deformations. The mean squared errors (MSEs) of experimental shape and simulation shape are 0.62 mm and 0.27 mm for flower structures. These results show that the proposed methodology can obtain target deformation in simulation and experimental tests simultaneously, which can be applied into the flexible deformation design of complex active composite structures in the future.