Study On The Computational Methods Of The Structural Acoustic Sensitivity

Acoustic sensitivity analysis based on spatial fourier transform and distributed source boundarypoint method (DSBPM) were investigated in this dissertation. Acoustic sensitivity informationprovides a quantitative estimate of the change of design variables, which indicates the change of theacoustical characteristics (sound pressure, sound intensity and sound power etc.) with respect to thechange of the design variable. Based on acoustic sensitivity analysis, engineers can decide thedirection and amount of design change needed to improve the objective function, and it has greatsignificance in mechanical optimization design.Considering the research significance and development of the acoustic radiation and acousticsensitivity analysis, problems existing in acoustic sensitivity analysis were investigated anddiscussed deeply, and then the corresponding solutions were provided. Based on spatial fouriertransform, calculation formulas of acoustic sensitivity analysis of cylindrical radiators were deduced,the computational efficiency was improved because of the use of spatial fourier transform. By usingthe DSBPM, acoustic sensitivity analysis which is suitable for a radiator with arbitrary shape wasanalyzed, and this method was applied in the structure interior acoustic sensitivity analysis, whichcan avoid the shortcomings of BEM and has higher computational efficiency. Based on the adjointvariable method and the DSBPM, acoustic sensitivity analysis based on the DSBPM with adjointvariable method was proposed, which can significantly reduces computational costs compared to thedirect differentiation method, as the number of performance measures is in general less than thenumber of design variables. A new distributed energy source boundary point method (DESBPM)was proposed here, based on the DESBPM, the high frequency acoustic radiation and sensitivityanalysis of a radiator with arbitrary shape could be achieved. The detailed research contents of thisdissertation are summarized as follows:In chapter one, the research significance of the acoustic sensitivity analysis was first elaborated,and then the development of the acoustic radiation and acoustic sensitivity analysis was discussed,by reviewing existing approaches of acoustic sensitivity analysis, the research topics of thisdissertation were determined finally.In chapter two, acoustic sensitivity analysis based on spatial fourier transform was investigated.Calculation formulas of acoustic sensitivity analysis of a plane radiator were deduced based onspatial fourier transform, its errors as well as the corresponding control methods were analyzed intheory and the correctness was verified with a numerical simulation of a simply supported plate.Based on spatial fourier transform, acoustic sensitivity analysis of cylindrical radiators was proposed, calculation formulas of acoustic sensitivity analysis of finite and infinite length cylinders werededuced, its errors as well as the corresponding control methods were analyzed in theory, and thevalidity was verified with numerical simulations of infinite and finite length cylinders.In chapter three, acoustic sensitivity analysis based on the DSBPM was proposed, the acousticsensitivity model based on DSBPM was established. According to the type of design variables,acoustic sizing sensitivity analysis, acoustic shape sensitivity analysis, acoustic frequency sensitivityanalysis and acoustic impedance sensitivity analysis were presented based on the DSBPM, thecorrectness and validity was verified by the numerical simulation and an experiment of a box, inwhich the advantage of computational efficiency is shown by the comparison of computational timewith BEM. Finally, the DSBPM was used to analyze the structure interior acoustic field, andstructural interior acoustic sensitivity could be achieved based on DSBPM, its validity was verifiedby the numerical simulation.In chapter four, acoustic sensitivity analysis based on the DSBPM with adjoint variable methodwas proposed, the acoustic sensitivity model based on this method was established, and thencalculation formulas were deduced. The proposed method can significantly reduces computationalcosts compared to the direct differentiation method, as the number of performance measures is ingeneral less than the number of design variables, the correctness of this method was shown by thenumerical simulation finally.In chapter five, a new distributed energy source boundary point method (DESBPM) wasproposed here for solving the high frequency acoustic radiation and sensitivity analysis, the acousticsensitivity model based on this method was established, and then calculation formulas was deduced.Based on the DESBPM, the high frequency acoustic radiation and sensitivity analysis of a radiatorwith arbitrary shape could be achieved, in which the shortcomings of other high frequency acousticanalysis methods could be avoid, its correctness was verified by the numerical simulation finally.In chapter six, researches in this dissertation were summarized, and the topics needing furtherstudy were proposed.