Research On Vibration Characteristics And Mechanical Properties Of Metamaterial Connected Pipe Structure

As an industrial lifeline,takeover systems are widely used in fields such as ships and aerospace.The vibration and noise problems of takeover systems can seriously reduce the safety and service life of mechanical equipment.The design of metamaterial nozzle structure based on the phononic crystal band gap mechanism can effectively control the vibration and noise of the nozzle system.Therefore,adopting new structural forms and mechanical performance design under pressure conditions as a new technological approach to study the vibration and noise problems of the connecting system will have positive scientific significance and practical engineering application value.In this paper,based on the basic theory and analysis method of phononic crystal band gap characteristics,a new type of phononic crystal metamaterial nozzle structure is constructed and designed according to the vibration and noise environment of the nozzle system.The pressure bearing and vibration isolation performance of phononic crystal metamaterial nozzle structure is studied by combining finite element method with experiment.Considering the configuration design of metamaterial nozzles under different bearing pressures,the mechanical bearing capacity and vibration isolation performance of different types of superstructure nozzles are studied.The main research content is as follows:Firstly,based on the requirements of low internal pressure bearing and the characteristics of disc spring configuration and phononic crystal periodic structure,a disc spring type phononic crystal nozzle structure is designed.The research results indicate that the vibration transmission rate curve of the disc spring type phononic crystal nozzle structure has low-frequency bandgap characteristics in the 0-440 Hz frequency band,and the overall isolation level is maintained at around 20 d B,indicating good isolation effect.At the same time,the nozzle structure can meet the internal pressure bearing requirement of 1 MPa.Secondly,a circular hollow disc spring type nozzle structure was designed,which has the characteristic of dual cycles.The research results indicate that the circular hollow disc spring type nozzle structure has fewer resonance peaks in the frequency range of 0-1000 Hz,and the maximum isolation level of the vibration transmission rate curve of the circular hollow disc spring type nozzle is located at 480 Hz,with a size of 63 d B.Meanwhile,parameter studies have shown that the hollow microstructure has a significant impact on the low-frequency bandgap,and using circular hollow will achieve better low-frequency broadband gap performance.Then,considering the local resonance band gap mechanism of phononic crystals,a disc spring metamaterial nozzle structure with local oscillators is constructed and designed.The research results indicate that the local resonance disc spring type nozzle structure has local resonance band gap characteristics at low frequencies,and has good vibration isolation effect in the 0-486 Hz frequency band.Then,considering the bearing capacity under high internal pressure,the variable thickness corrugated phononic crystal metamaterial nozzle structure is constructed and designed.The results show that the maximum bearing capacity of the variable thickness corrugated phononic crystal metamaterial nozzle structure can reach 4.5 MPa,and it has good low-frequency vibration isolation performance.Finally,combined with the negative Poisson’s ratio metamaterial structure,a negative Poisson’s ratio metamaterial nozzle structure is designed.The results show that the designed metamaterial nozzle with negative Poisson’s ratio is still in the elastic range under 1 MPa internal pressure.Compared to the disc spring type pipeline,through the negative Poisson’s ratio structure design,the nozzle structure has a negative Poisson’s ratio characteristic of increasing internal pressure and decreasing axial stiffness,achieving that the nozzle structure still has lower axial stiffness under high internal pressure and obtaining low-frequency broadband bandgap characteristics.