A temperature-regulated multi-material compression-torsion metamaterial with local bistability

In this paper, based on the compression-torsion coupling structure, we designed and fabricated a structure that exhibits a temperature-controlled local bistability phenomenon during uniaxial compression at different temperatures. In the structure, based on the quadrilateral rigid frames, the flexible connecting bands are hinged to the frames by pins, and the shape memory polymer inclined struts are bonded to the frames. The compression-torsion coupling causes the bend of the inclined struts and the rotation of the rigid frames, then causing the connecting bands to post-buckling. The inclined struts can adjust and control the deformation process under thermal loads, because the modulus of the shape memory polymer is controlled by temperature, so that the deformation of the structure is reversible/irreversible under programmable temperature/displacement loads. The analytical model and numerical simulation show that the local bistability can be achieved under temperature control and different boundary conditions. An assembled metamaterial structure is fabricated by combining 3D printed parts. The relationships between the reversibility/irreversibility of the structural deformation and temperature/displacement loads are verified by experiments. The local bistable phenomenon enables the structure to remember the history of the load, providing inspiration for new functional designs in the fields of intelligent memory, encoding display, and vibration energy absorption.