Novel metamaterial wave barrier structure with multiple frequency wide band gaps for rail transit vibration isolation

As a new kind of artificial composite material, locally resonant phononic crystal (LRPC) can attenuate and suppress the propagation of elastic waves in certain frequency range, which has a broad application prospect and value in the field of vibration and noise control. The traditional LRPC can only open one band gap (BG), but the vibration and noise in practical engineering are often multi-band, so the traditional LRPC cannot effectively cover the target frequency range, and the efficiency of vibration and noise reduction is greatly limited. In response to the shortcomings of traditional LRPC, this paper designs a novel locally resonant phononic crystal with multiple primitive cell combination structure (LRPCWMPCCS), which is a locally resonant supercell structure composed of five types of locally resonant single primitive cells. Firstly, the band structure of the LRPCWMPCCS is calculated using the finite element method, and compared with the band structure of traditional LRPC. Secondly, the frequency response function of the LRPCWMPCCS is calculated to evaluate its attenuation effect on elastic waves in the BG frequency range, and the generation mechanism of its locally resonant BG is explored by analyzing the displacement field and energy distribution characteristics at the BG edge. Then, the equivalent model of the LRPCWMPCCS is established for theoretical calculation of the BG range. Finally, the vibration isolation performance of LRPCWMPCCS wave barrier in practical engineering is analyzed, and the application prospects of the LRPCWMPCCS are discussed. The results show that the LRPCWMPCCS designed in this paper can open the multifrequency BGs, and the BGs width is wider. The number of BGs opened is positively correlated with the type of primitive cells inside the LRPCWMPCCS. Within the BG frequency range, the LRPCWMPCCS has a good attenuation effect on vibration waves, with attenuation values exceeding 20 dB. The spring-mass system equivalent model of the LRPCWMPCCS can accurately calculate its BG range and has good accuracy. The LRPCWMPCCS wave barrier has remarkable control and attenuation effect on vibration. Among them, the maximum vibration acceleration of traditional LRPC wave barrier and LRPCWMPCCS wave barrier is reduced by 18.51% and 39.50%, respectively. The relevant research results of this paper have great value and prospects in the design of LRPC with multifrequency and wide BGs, which can also provide a new method and idea for solving vibration and noise problems.