LAUSR

Abstract Robots are designed to achieve muscle contraction, body curling, stress response, and other complex movements. Inspired by the arm configuration and compression–torsion cubic mechanical metamaterials (CTCMM), the CTCMM with variable cross-section (V-CTCMM) and the offset CTCMM with variable cross-section (OV-CTCMM) by bionic designing are proposed. The novel microstructure can meet the shape requirement of the whole structure section. Through theoretical derivation for simplified cylinder models, the variation laws of torsion angle under torque in the V-CTCMM and OV-CTCMM are obtained. Three specific unit cells are studied under compression by numerical simulation and experiments. Compared with double rods CTCMM, the multi-rods CTCMM with variable cross-section (MRV-CTCMM) shows bigger torsion angle and larger stiffness. According to the characteristics of unit cells, the whole structure is constructed in the radial and axial direction with multiple expansion modes. Considering the stiffness of the structure in radial direction, straight rods and chiral rods construction methods are proposed to improve in-plane stiffness. The result shows the dumbbell structure can reach the best torsion angle among gradient structures in axial direction. With the progress of micro-nano manufacturing technology, 3D V-CTCMM shows a broad industrial application prospect in the fields of deformable structure, shape-memory controller, intelligent flexible microelectronics, and so on.