Multipolar Resonance And Vibration Attenuation Mechanism Of Star-Concave Hexagonal Metastructures

With the rapid development of urban rail transit,people’s requirements for ride comfort have also increased,and the problems of vibration and noise need to be solved urgently.The vibration attenuation performance of the star-concave hexagonal metastructure is studied,and the low-frequency vibration attenuation regulation law is obtained,and the optimized design is applied to the train floor vibration attenuation.A 16-DOF mass-spring analytical model is established to study the elastic wave propagation and vibration attenuation mechanism of star honeycombs.The bandgap boundary modes indicate that the bandgap mechanism is a combination of modes such as monopole,dipole,quadrupole and rotational resonance.According to the band gap mechanism,adjusting the parameters opens the low frequency band gap between the second and third dispersion curves,and obtains the regulation rule of the band gap.The harmonic response of the finite periodic structure verifies the existence of the band gap and exhibits anisotropy in the frequency range of the negative slope of the dispersion curve.An elastic wave propagation model of a concave hexagonal honeycomb with 8 degrees of freedom is established.The energy overlap occurs in the low frequency dispersion curves,and the dispersion curves are classified according to the modes before and after the intersection.The harmonic responses of finite-period lattices show that when the masses in the modes move in the same direction,a directional band gap is formed in their perpendicular directions.The composite honeycomb structure composed of star honeycomb and concave hexagonal honeycomb with lower frequency band gap is studied by finite element method.The harmonic response of the finite periodic structure shows that the resonance peaks in part of the bandgap resonate at the input end,which can realize energy harvesting while isolating vibrations.The composite honeycomb structure is optimized by genetic algorithm,and the structural parameters with vibration damping frequency of 1000 Hz～2000 Hz are obtained.Through simulation verification,it can effectively attenuate the excitation of the real vehicle.The static performance of the block and plate damping structures is preliminarily verified,and the modal frequencies are higher than 20 Hz.A composite honeycomb sample was made to conduct vibration tests to verify its vibration attenuation performance.