User:Swarnkarsudhir/Transfer path analysis

Tranfer path analysis or TPA is an approach to diagnose sources of low frequency noise and vibration in mostly but not limited to automotive industry. Energy coming from different sources e.g. engine, fans etc. is transferred to the target (driver or passenger) location in the form of noise and vibration through different structural and air-borne paths. TPA is used to estimate and rank the contributions of different paths to a specific target location to indentify the root cause of noise and vibration. The source, once identified, can then be treated to address the noise and vibration problem.

Introduction
Basic transfer path analysis involves estimation of frequency response function between the source and the target. This can be done experimentally or analytically. Experimental approach involves removal of the energy source e.g. engine and then excitation of the source mount point with a provision to measure the magnitude of excitation. Simultaneusly the response at the target location is measured. The response could be sound pressure level or acceleration or both depending upon if it noise or vibration to be studied.

There are sensors at other locations between the source(s) and the target(s) also, where the response is measured. These locations are called indicator points.

Frequency response function between target and source and between indicator points and sources are thus obtained.

Energy source is then mounted back and run under normal operating conditions and the response is again measured at the target location.

Purpose
When is TPA used?

Refining NVH Troubleshooting Prototype stage

Experimental Methods
How is TPA done?

1. Remove the source 2. Indicator/Target positions 3. Measure transfer functions 4. Measure operating conditions 5. Analysis