Vibration Transmissibility Characteristics of Occupied Suspension Seats

摘要

A study was conducted to evaluate the transmissibility characteristics of occupied suspension seats in multi-axis vibration environments using locomotive seats. Exposures included a flat acceleration spectrum and two signals extracted from locomotive floor data. The multiple input/single output system transfer matrix and overall transmission were calculated at the seat and several anatomical sites. While the transmissibilities showed minimal off-axis contributions to the seat responses, off-axis contributions were evidenced at the chest and head for the flat spectrum exposure. Off-axis vibration and other factors contributed to the seat, chest, and head motions during exposure to the locomotive vibrations. Significantly higher overall transmissions were observed in the vertical direction at the seat and head, and in the fore-and-aft and vertical directions at the chest using the suspension seat with shocks removed. The relatively large, low frequency multi-axis motions observed at the chest may be a contributor to discomfort in locomotive engineers. Seat Effective Amplitude Transmissibility values were determined for estimating the overall seat pan acceleration from monitored locomotive floor accelerations for targeting potentially harmful vibration exposures at the cab seat (ISO 2631-1: 1997).