With the development of sound radiation theory, the research on sound radiation of transmission case is more in-depth abroad. J. Missaoui and L. Cheng analyzed the irregular cavity structure. The integral mode method is used to analyze the non-uniform shell and the acoustic relationship of the whole structure is obtained. In the same year, Tanaka eiichirou et al. Obtained a method for the prediction of transmission structure vibration and noise through comprehensive research on transmission box vibration characteristics and transmission gear impact prediction radiation noise. Then, the reliability and accuracy of this method were verified by testing the horizontal and vertical noise and vibration data of transmission. Mohamed Abbes et al. Studied the vibration noise and radiated noise of transmission deeply by combining Rayleigh integral method with finite element method and according to the structural characteristics of transmission.
As some foreign software development companies pay more and more attention to vehicle NVH, some software and test systems applied to NVH are gradually developed and improved. Among them, LMS company has made in-depth work in the test and theoretical analysis of vehicle vibration and noise, p.j.g. van der linden and Ph.Vart Through the acoustic research of the body panel, the influence degree of the body on the overall noise is obtained by the test method. 50. Gielen, win Hendrix completed the research on noise source location, quantification and optimization of vehicle structure vibration under road excitation. On the basis of a lot of research and experimental work, LMS company has gradually developed and improved the software LMS sysnose for structural acoustic analysis.
In addition to LMS company, engineers from various countries put forward new ideas and methods and developed more powerful programs for the research of the whole and transmission based on the structural modal analysis. Among them, the laser velocimeter developed by the laser room of the Institute of noise and vibration (ISVR) can monitor the working condition and performance of the equipment, and can also be used as a test tool to judge the noise. B & K Company in Denmark has developed and put into use the space sound field conversion technology (STSF), which provides a complete description scheme for the calculation and prediction of noise sources. Through the approach test of noise sources, the sound field data obtained from the test can be converted to any position by using this technology.