Research On Cavity Acoustic Modeling And Sound Absorption Optimizing Based On SEA

As the cabins and the main contact areas of the body of cars,trains and other transportation,cavity structure's noise is closely related to the comfort and the level of acoustic design of the cabin directly affects the level of its cavity noise.Therefore,studying the cavity modeling,discussing the low noise design and optimization,and controlling the chamber noise has an important theoretical and engineering significance for improving the occupant's ride environment.Based on statistical energy analysis method,orthogonal optimization theory and mixing optimization design method.The article has carried on the research and the discussion in acoustic modeling of sound cavity structure,optimization of noise reduction and optimization design of sound absorbing material mix.The main work and achievements are as follows:Aiming at the problem that the lower limit frequency is high in the SEA model of the acoustic structure,this paper presents a sensitivity analysis method for the modal number of the acoustic structure parameters,infers the mathematical model of modal number sensitivity of cavity structure subsystem and calculates the first order sensitivity of the modal number of the subsystem to the thickness,area,material density and cavity volume.First,the response surface design method is used to judge the significance of each factor to modal number.Second,the range of the factors of the target response condition is solved using response optimizer.Third,the sea model of the cavity structure can be initially satisfied with the prediction of intermediate frequency noise.Thus,the development of the frequency limit of statistical energy analysis is realized by modeling,which provides a new way to predict the intermediate frequency noise of cavity structures.The acoustic radiation power model and SEA simulation model of cavity structure are established.A significant excitation source under multi-source excitation conditions is obtained by setting multiple sets of simulation tests to analyze the influence of the position,quantity and characteristic of the excitation source on vibration of the vocal structure and acoustic characteristics.The article uses a single source or multi-source control method to achieve the sound source noise reduction optimization,designs the cavity structure of sound absorption factor level and orthogonal optimization table by orthogonal optimization theory and method and concludes the optimal combination of the total sound pressure level and the main peak frequency in the intracavity evaluation point by VA One software simulation calculation and optimization in different combinations of factor levels.The dissertation has put forward the concept and type of sound absorption design,built SEA model of mixed sound absorption and studied the absorption characteristics of polyester,foam,cast foam,polyurethane as well as melamine by simulation calculation.Focus on uniform mixing sound absorbing material,this dissertation compares the characteristics of the various of combinations of different sound absorbing materials and discusses the design method of sound absorbing material mixing optimization which aims at evaluation of sound pressure level control and sound absorption material characteristics.Finally,the optimal ratio of a variety of sound absorbing materials which meets the noise reduction standard is obtained.Moreover,this paper studies Taguchi design method for sound absorbing material of laminated mixed material and determines the importance of different control factors in the corresponding frequency band using SNR and mean analysis.At last,this paper finds the best combination of laminated mixed sound absorption.It provides a new method to realize the high performance sound absorbing material satisfying the noise reduction demand by optimizing design.B&K3560C acoustic test system and impedance tube test system has been widely used to carry out experimental study on sound absorption characteristics of laminated mixed sound absorbing materials.The correctness and validity of the optimized results of laminated mixtures of sound absorbing materials are verified.