Acoustic Performance Analysis And Optimal Design Of The Ossicular Silencer

Noise pollution is one of the four major pollution in today’s society. It’s being more serious with the development of industry and has a grave impact on human’s physical and mental health. Reactive silencers have simple structure, they are easy to clean and often adopted to tackle the low-to-medium frequency noise, they are widely used to attenuate duct noise in exhaust systems and ventilation systems. It is the main content to improve the acoustic performance and reduce the size and mass of reactive silencers.A new silencer—ossicular silencer was introduced in this dissertation. In order to analyze its acoustic properties and principles, the 3D finite element model and 1D simplified model based on plane-wave theory were established, control variate method was used to study the related parameters.In order to improve the performance and reduce the mass of the ossicular silencer, deterministic optimization and uncertainty optimization based on response surface methodology(RSM) were used to optimize the structure parameters of the ossicular silencer. Sample points were obtained by central composite design(CCD), the quadratic polynomial model was constructed based on response surface methodology, and the fitting accuracy was tested. Response surface methodology combined with genetic algorithm II(NSGA-II) was applied to optimize the structure parameters of the silencer. In the optimization, the average transmission losses(TL) of the low frequency range and the broadband were chosen as optimization goals, several structure parameters(width of the main duct, depth of the enclosed cavity, length of the enclosed cavity) were chosen as optimization variables.Through analyzing the acoustic properties of the ossicular silencer, by choosing proper design parameters, this silencer can function effectively as a broadband silencer. The cavity volume is not a crucial parameter in the design of the ossicular silencer, so it can be more compact. The optimized ossicular silencer has better performance and lighter weight. The optimization results indicate that it is valid to optimize the structure parameters of silencers by combining response surface methodology with genetic algorithm. The theory of uncertainty and robustness was applied into the optimization of the ossicular silencer, it improved the performance of the silencer, reduced the sensitivity of optimization goals to the design parameters’ fluctuations, so it has a certain value in the engineering field.