Novel metamaterials with thermal-torsion and tensile-torsion coupling effects

Struts with different thermal expansion coefficients are employed to design novel 3D chiral metamaterials, which interestingly show twist deformation under both temperature variation and uniaxial load. Analytical expressions on the twist angle of the proposed metamaterials are established to relate with geometry of cell structure and material properties of struts, showing good agreement with numerical simulations. Both theoretical analysis and numerical simulations suggest that the tensile-torsion and thermal-torsion coupling effects of the metamaterials can be tuned by tailoring cells’ geometric configuration and material selection. It is shown that the inclined rods’ angle and the rods’ stiffness play important roles in both the thermal-torsion and tensile-torsion coupling effects. Based on that, the conditions corresponding to maximum tensile-torsion and thermal-torsion coupling effects were determined, respectively. Besides, the thermal-torsion coupling effect is also proportional to the rods’ thermal expansion coefficients. Moreover, it is shown that the two coupling effects are strongly correlated to each other. The contour maps of the twist angle of the metamaterial are obtained under simultaneous temperature change and uniaxial load. The proposed metamaterial is expected to find applications in sensors, actuators and wave convertors, especially in environments of alternating temperature changes.