Calculating Partial Contribution Using Component Sensitivity Values: A Different Approach to Transfer Path Analysis

Transfer Path Analysis (TPA) is a widely used methodology in Noise, Vibration and Harshness (NVH) analysis of motor vehicles. Either it is used to design a vehicle from scratch or it is applied to root cause an existing NVH problem, TPA can be a useful tool. TPA analysis is closely related to the concept of partial contribution. The very basic assumption in TPA is that the summation of all partial contributions from different paths constitutes the total response (which could be either tactile or acoustic).

Another popular concept in NVH analysis of vehicles is the component sensitivity. Component sensitivity is a measure of how much the response changes due to a change in one of the components of the system, i.e., the thickness of a panel or elastic rate of an engine mount. Sensitivity rates are more popular among CAE/Simulation community, simply because they are reasonably easy to calculate using mathematical models.

This paper illustrates a simple mathematical equation that relates the partial contribution to the component sensitivity for a linear elastic isolator (an approximation of an engine mount or a suspension bushing). Thus, it is possible to calculate the partial contribution of a linear elastic isolator to an acoustic or tactile response by knowing the component sensitivity of that response to the specific element. This new approach to compute partial contributions reduces numerical and experimental analysis cost and time. Examples and applications, both numerical and experimental, are presented.