Research On Ship Vibration Reduction And Noise Reduction Based On Phononic Crystal Band Gap Characteristics

A phononic crystal is an artificially periodic structure,specific frequency elastic waves have no corresponding eigenmodes and can’t propagate in the structure.By reasonably designing the parameters and arrangement forms of the local resonance phononic crystal‘s scatterers,the low-frequency broadband vibration isolation and broadband sound insulation of the structure can be realized,which has a good application prospect in the field of ship vibration and noise.This paper first introduces the phononic crystal theory as well as vibration and noise theory.The band gap characteristics of BRAGG phononic crystals are solved with the finite element method and plane wave expansion method.Band gap characteristics of the local resonant phononic crystals of the additional cylindrical scatterers are solved,the effects of the parameters on the band gap characteristics are further qualitatively analyzed.The phononic crystal plate structure is introduced into the ship vibration isolation system,the vibration isolation and sound insulation effects are studied.The influence of geometric parameters and physical parameters on the vibration reduction and sound insulation effects of local resonance phononic crystal plates and stiffened plates is analyzed.On this basis,the phononic crystal plate design scheme with different numbers and different forms of scatterers on the original cells is further studied.The results show that the structure can produces low-frequency broadband vibration isolation and broadband sound insulation by rationally designing the parameters of the scatterers.The typical multi-stage vibration isolation system of the ship is selected,and the ordinary steel plate structure is replaced by the local resonance type phononic crystal plate structure.The vibration isolation characteristics of the multi-stage vibration isolation system are simulated and analyzed.The results show that the multi-stage vibration isolation system with additional phononic crystal plate structure has better vibration isolation effect in the range of the band gap frequency.