Research On The Acoustic Radiation Characteristics Of Asymmetric Elastic Structure

Rectangular plates and cylindrical shells are the main structural forms of underwater vehicles.The study of their vibration and acoustic radiation characteristics is very significant.In the past,the research focused on symmetrical structures such as rectangular plates,cylindrical shells and the structures with uniform ribs while the research on asymmetric structures is very rare.The asymmetric structure has different acoustic and vibration characteristics from the symmetrical structure and has important research significance.In this paper,the finite element numerical calculation method is used to compare the vibrational acoustic radiation of asymmetric and symmetric elastic structures.Combined with the mode shape analysis,the vibrational acoustic radiation characteristics of asymmetric elastic structures are studied.In this paper,the asymmetric acoustic characteristics of rectangular plate and cylindrical shells are studied.For the rectangular plate,the influence of the asymmetric distribution of the excitation force,the asymmetric distribution of the ribs,the asymmetric distribution of the mass load and the asymmetric distribution of the boundary conditions on the acoustic vibration characteristics of the structure are studied.The results show that because of asymmetric ribs the mode shape of the rectangular plate is broken,which suppresses some strong symmetrical resonance radiation peaks.It can reduce the level of acoustic radiation that more ribs are ranged near the excitation force position.When the asymmetric excitation force is applied,more vibration modes are excited,the number of radiation peaks is increased,and the radiated sound power is reduced in a certain frequency band;the asymmetric distribution of the mass load can destroy the symmetry of the overall mass distribution of the structure and stimulate more non-symmetry.Asymmetric mode,which produces more small radiation peaks,suppresses some strong symmetrical resonant radiation peaks;Asymmetric boundary constraints can significantly change the original symmetric mode and change the original vibrational acoustic radiation spectrum structure.For the cylindrical shell,a similar analysis method is used to study the influence of the asymmetric distribution of the rib and the asymmetric distribution of the excitation force on the acoustic radiation of the cylindrical shell.The conclusion is similar to that of the asymmetric rectangular plate.The research in this paper shows that the asymmetric design can reduce the uniformity of the elastic structure,thereby suppressing the strong radiation mode of the damaged structure,and suppressing the significant vibrational sound radiation peak.The asymmetric design can change the participation degree of different modes.Through the targeted vibration and noise reduction design,the vibration and sound radiation of the rectangular plate and the cylindrical shell structure can be controlled.