Dynamic Analysis of an Automatic Transmission

Modern vehicles are designed for quiet interior with lower engine and exhaust noise levels. Under such circumstances, gear whine and rattle become one of the significant contributors towards in-cab noise, besides wind and road noise. Present paper deals with dynamic analysis, simulation and validation of the transmission system model for observed gear whine inside the cabin of a passenger car during its running condition. The exercise included development of an accurate numerical model to enable prediction of noise transmission from automatic gearbox to cabin structure. Experimental Modal Testing (EMT) of automatic transmission and suspension components, Multibody simulation of automatic transmission and Finite Element Analysis (FEA) of components and subassemblies followed by component and system level response correlations were carried out. Detailed methodology adopted for the exercise is discussed in the paper.