| The sharp pressure fluctuations caused by structural collisions can lead to transient noise with large amplitude,short duration,frequent occurrence,and complex frequency components within the surrounding medium.For multiple fields such as aviation,aerospace,shipbuilding,and rail transit,in-depth research on the formation mechanism and radiation laws of structural collision noise has important academic and practical application value.In naval weapons and equipment,the impact noise on ships not only causes great harm to the physical and mental health of personnel,but also seriously threatens the battlefield survival ability and combat performance of ships.Therefore,how to accurately predict and control the impact and collision noise of structures has always been a hot topic of close attention in the academic and engineering fields.Based on the collision noise theory and numerical research methods of common structures,this thesis systematically carried out numerical and experimental research on the transient impact noise radiation characteristics of elastic spherical shells,solid spheres,solid cylinders and cylindrical shells,Breakthrough the problem of low accuracy in predicting transient impact noise using traditional steady-state solution methods.In addition,to address the issue of structural impact noise control,this article adopts a research method that combines experimental and numerical simulation,aiming to explore the influence of different influencing factors on the amplitude of radiation noise generated by elastic collisions between common structural bodies mentioned above.Based on this,further numerical research on the opening and closing collision noise of complex missile cylinder cover launch devices was carried out,and based on the numerical simulation results,a feasible solution is provided for the effective control of collision noise during the operation of the cylinder cover.In view of the fact that the research on the impact noise of thin shell structures has not been fully carried out at present,this thesis takes the elastic spherical shell as the research object,adopts the numerical research method of the joint time-domain finite element method and the transient boundary element method,obtains the transient radiation sound field of the impact noise of the elastic spherical shell,and carries out experimental verification.The experimental results are in good agreement with the numerical results.On this basis,a timefrequency analysis of the impact noise of an elastic spherical shell was conducted,and the results showed that the impact noise of the spherical shell includes two components:acceleration noise and self resonance noise.Based on simulation methods,the influence of key factors such as collision speed,shell thickness,shell diameter,and shell shape on the impact noise of spherical shells was further studied.In addition,based on experiments and numerical models,the mechanism and composition of impact noise generated by the collision between solid spheres,cylinders,water filled spherical shells,cylindrical shells,and other structures were revealed.Finally,this thesis draws inspiration from the simulation research method of impact noise of simple structures,combined with the dynamic software LS-DYNA and acoustic software Virtual Lab has established a mechanical and acoustic numerical model for the impact noise of the cylinder cover switch device.Based on this,the impact speed of the cylinder cover,the driving force of the hydraulic top rod,and the characteristics of the pressure bearing base material on the impact noise of the cylinder cover have been analyzed.Based on the numerical results,measures for controlling the impact noise of the cylinder cover opening and closing have been proposed.The research results of this article can provide strong support for the design and performance improvement of related equipment,and are expected to be applied in noise control problems in fields such as ships,aviation,and aerospace. |
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