Acoustic Signature for Seat Rattles

Automotive seat rattle has a large contribution in customer NVH satisfaction, as there is a close interface between the passengers and seat. The vibration from the road and other sources in the car like the engine are transmitted to the seat through the different paths which can be the cause of rattling noise in different frequency ranges from the seat. Seat structure as well as its components can be sources of rattle noise based on their physical characteristics. Therefore the main objective of this project was to characterize the acoustic signature of the seat rattle noise which can be used for noise source identification and structural NVH optimization. For this purpose, different noise measurement and structural tests were done on a Holden VE passenger seat manufactured by FUTURIS Company. A sine sweep from 5-100 Hz was used as the input vibration for the tests to simulate the real life driving conditions and the vibration and noise responses of the seat were measured and analysed using different equipment and software packages. The methods used included modal testing and analysis, noise measurement and impact hammering test on different seat components. The seat was divided in to 3 main areas including: Rails, Seatback and Headrest. The obtained major rattle noise frequencies were correlated with corresponding structural modal frequencies. This comparison and additional impact hammering results lead us to identify the acoustic signatures and corresponding sources of the seat rattle noise. The acoustic signatures database has therefore been developed for the automotive seat.