A Comparison of Occupied Seat Vibration Transmissibility from Two Independent Facilities

Abstract

Ford Motor Company has developed a corporate engineering test procedure focused on the vibration transmissibility of the occupied automotive seat. The procedure allows Ford to assess, in a consistent manner, the performance of (1) prototype-level seats specific to new/future programs and (2) production-level competitive seats. As part of the procedure, a complete seat system is mounted to a human-rated platform using a dedicated fixture, engaged by persons matching specific anthropometric characteristics, and excited vertically, laterally, and fore-aft with external actuators under laboratory conditions. Johnson Controls is one of the few seat suppliers that have the equipment and expertise required to execute this procedure. Using Ford’s procedure, the objective of this paper is to compare and contrast the test results, expressed both statistically and graphically as transfer functions, produced by these two independent facilities. Because of the proximity of the two laboratories, it was possible to use the same production level seat and the same occupants at both facilities. The results showed good agreement in all excitation directions. Based on the strength of these results, discussions concerning specific noise, vibration and harshness (NVH) and ride quality requirements, which Ford cascades to Johnson Controls on a program-by-program level, can begin from a common basis. The common understanding, while yielding a more efficient seat development process, should lead to more comfortable vehicles.