Abstract:
For the rapid design of acoustic metamaterials using hollow pipes, an analytical method for solving the equivalent parameters of acoustic metamaterials made of hollow pipes with regular polygon section is presented. In this method, the total section deformation of a hollow tube is approximated as the sum of the bending deformation of fixed-end beams and the radius contraction deformation of a regular polygon. By introducing the plane strain approximation, the beam-bending part can be solved by the stress function method, and the radius contraction part can be obtained by solving the constitutive equation. Theoretical and finite element simulation results of equivalent moduli and equivalent densities with different parameters are compared, and a wavefront deflection lens is designed. The results show that the equivalent modulus is positively correlated with the number of section edges and the ratio of wall thickness to section outside diameter. The equivalent density is positively correlated with the ratio of wall thickness to outside diameter, but negatively correlated with the number of section edges. Theoretical results agree well with simulation results. Meanwhile, in the aspect of plane wave deflection, the lens made of hollow pipes works as good as the one designed using effective parameters directly. Therefore, this model can be used to quickly calculate the equivalent acoustic parameters of metamaterials.