In order to reduce the powertrain vibration and improve the sound quality in a passenger car, it is important to understand the actual operating vibration behavior on a powertrain assembly. The static modal analysis with the two point excitation technique was done to understand the fundamental vibration characteristics of the structure, and the mode shape could be exactly estimated. The Operating Deflection Shape (O.D.S) analysis was carried out to understand the actual vibration behavior during engine running. As a result, we have found the following conclusions. The deflection shapes of the even and odd order multiples of engine rotation below the resonant region have rigid body shapes like a pitching, rolling and others. But the half order deflection shapes show a combination of rigid body shapes and a elastic deformation, and the later shows clearly the torsional deflection. In the resonant region, the operating deflection shapes have high correlation with natural modes obtained by the static modal analysis at similar frequencies.
展开▼
