Research On Relationship Of Vehicle Cabin Structural Design And Low-frequency Noise

Based on FEM and BEM theory, a series of research on one certain excavatorcentering on the relationship between the vehicle’s interior noise level and all of itsstructural parts was launched. A computer-aided-engineering （CAE） simulationcombining with experiments was conducted to identify the cab’s main noise source andto find structural defects during the preliminary design stage，which can guide aneffective optimization. Acoustic finite element method and acoustic boundary elementmethod were involved during the whole process.A structure FE model for the excavator cab was established in the paper. On thisbasis, an acoustic cavity FEM model and a coupled cavity BEM model were generated.The modal analysis was done to know the cabin’s the inherent structural characteristicsand its acoustic characteristics to point out the main influence part of the weak modaland advantageous acoustic mode. And the vibration results from the vibration analysisupon modal method can not only to be used as initial values for radiated noise analysisand noise reduction analysis but also to find out the larger vibration structures due toouter excitation.Test of focused field sound pressure under road condition was done. And thefocused frequency where the peak values of acoustic pressure was has been found bycalculating coupled field point sound pressure and the model has been proved accurateto some extend by contrast the computational results to test results. To the frequencyunder peak sound pressure, the more contributing structural modes and panels havebeen recognized by means of modal contribution analysis and panel contributionanalysis.By integrating the stimulation results and test results and referring to related theory,the significant influence of the panel vibration to cab’s interior noise was obviouspresented. In the meantime, the peak acoustic pressure has been controlled with thestiffness of the weak panel enhanced by topography optimization. Then the modalanalysis and an interior acoustic field coupled frequency response analysis wasre-calculated to the cabin, which has been optimized already and effective results havebeen achieved.