Study on the calculation of car interior low frequency sound pressure based on equations

• 1、College of Engineering and Technology, Southwest University, Chongqing 400716

Abstract：Prediction and control methods of car interior low frequency noise used nowadays gradually show such defects as large amount of calculation work, high difficulty to spot weak area of car body, time-consuming for structure improvements. A new fast prediction and control algorithm for car interior low-frequency noise is urgently needed. Therefore, based on the equation of interior sound pressure of enclosed cavities, a calculation method of car interior lowfrequency sound pressure based on formulas was studied. Firstly, the calculation methods of the parameters in the equation of interior sound pressure of enclosed cavities were discussed, when the natural frequencies and mode shapes of structures and acoustic cavities were calculated by finite element methods (FEM). An equation-and-FEM based calculation method of enclosed cavities\' interior sound pressure was developed. Secondly, the experimental platform was built, and by calculation and experiment the accuracy of the new method was verified. Finally, the influence of element length and element shape on the accuracy of the new method was discussed. Then this new method was used to calculate the interior low frequency sound pressure of a hatchback car and a notchback one. The application of the new method in complex car body structural-acoustic coupled system was discussed. Research results show that the new method can be used in calculation of the interior sound pressure of any-shaped structural-acoustic coupled systems. When the element length meets the accuracy requirement and the number of triangular elements is small, its calculation accuracy is at the same level as the traditional full coupling method.

Keywords： vehicle engineering structural-acoustic coupled system interior low frequency sound pressure formula method finite element method.