Identification of a vibration transmission path in a vehicle by measuring vibrational power flow

In a vehicle, many isolators are used to attenuate the vibrational transmission from an engine to a car body. Vibration power flow through these isolators gives information on the flow of the vibrational energy generated from an engine or induced from the road. The measurement of vibrational power flow at each isolator identifies the vibration transmission path in a vehicle. In this paper, a simple equation is derived for the calculation of vibration power flow at the isolator of a passenger car. This equation is used for the measurement of the vibrational power flow at 18 isolators of a test car. From these results, the vibrational transmission path of the test car is identified and is extended to the reduction of the structure-borne noise in the compartment of the test car. Major vibrational transmission is at the front end of the centre member of the test car. The modification of the front part of the car body yields a reduction of the sound pressure level at the major noise peak.