Research On Vibration Analysis And Prediction Of Radiating Noise Of Engine Shell

The vibration of the engine is one of the important reasons for thenoise. Previous studies have shown that the surface radiation noise is themain noise of the engine, the proportion of the whole machine noise isvery high. Based on motorcycle engine as the research object, this paperUSES the Finite Element Method with Boundary Element Method,combined with the experimental research, a deep study of vibrationcharacteristics and the engine shell surface radiated noise prediction.A solid model was built in the Pro/E software, and carries on thefinite element pre-treatment in the ANSA, adopting the tetrahedron gridmeshing model. Using finite element analysis software ANSYS to carryon the free modal analysis, get the inherent frequency and compared tothe natural frequency measured in experiment for verifying thecorrectness of the finite element model, and constrained modal analysiswas carried out on the shell. Modal analysis results show that the shell ismainly for bending modal, the bent area in the center of the shell. Basedon the vibration mode of the modal analysis，changing the engine shellmodel by reinforcing and thickening for increasing the natural frequencyof the shell, and exploring the influencing factors of natural frequency.The vibration test experiment of engine surface was carried out, andexplores its surface vibration situation. Calculated transient analysis wascarried out on the shell, the surface of the vibration acceleration datameasured with experiment and comparison between the correspondingpoints of the acceleration data error was within the scope of the permit.Extract the transient analysis of the dynamic response of the shell surfaceacoustic analysis data as the boundary conditions, and using SYSNOISEsoftware for surface radiated noise acoustic analysis, get the radiationsound power levels of noise spectrum and acoustic intensity distribution.The engine shell surface sound intensity measurement experiment wascarried out, and get the surface sound intensity distribution, and Learnedthat the noise radiation of main parts was near the center of in theoutermost layers. The acoustic simulation results compared with theresults of sound intensity measurement, verify the reliability of acoustic simulation prediction.