Shape memory behaviors of three-dimensional five-directional braided composites with different axial yarns arrangements

The effect of braided structure on shape memory behaviors of 3D braided composites is critical to design the responses of the composite under external fields. Here we report the effect of axial yarn on shape memory behaviors of three-dimensional five-directional (3D5d) braided shape memory polymer composites (SMPCs) under bending. It was found that the axial yarns will improve bending stiffness and electro-thermal behaviors significantly. The thermomechanical deformation and shape memory effect of SMPCs are influenced by the braiding structural parameters. Specifically, the 3D5d SMPCs exhibits a 53.6% increase in bending recovery force and a faster shape recovery speed than those of 3D four-directional SMPCs. We found from finite element analyses (FEA) that the axial yarns positions influence the inner stress distribution and shape memory behaviors of SMPCs. The axial yarns distributed on both sides of SMPC influence the shape memory behaviors more than those of the middle layer.