Search Results

Continuing effort in measuring human vibration response results in a new design of vibration comfort dummy. The difference between this new dummy and other mechanical dummies is that (1) it uses a soft human-tissue like lower torso so it matches compliance better than the previous ones, and (2) it utilizes the spring and damping characteristics of the compliant lower torso. The lower torso is integrated with a spring-mass load simulating the top body of human so that the integrated dummy consists of two parts. This unique design greatly improves the accuracy and stability of transmissibility measurement and provides a direct application tool in seat prototype development. The results measured with dummy are compared with that measured with 3 human subjects in different percentiles and good match is found in the first transmissibility resonance and overall vibration response.

In order to specify the human dynamic comfort of seat vibration, a lot of work has been conducted in laboratory research. From the seating manufacturer's perspective, the author proposed a test method to measure the seat ride comfort by using a spring-mass dummy which was designed to match the human response in low frequency in vertical direction. A hydraulic table was employed as the excitation source to the occupied seat. Two seat samples, both measured with human occupants before, were used for this study. For simplicity and comparison, a sweep sine signal in vertical direction was used as the excitation signal. The transmissibility results measured of the dummy loaded seat were compared to those of human occupants. In this paper, a continuing effort focused on correlating the vibration response from dummy occupied seat to that from human occupied seat. A consistent relation was shown between the two measurements.

Transmissibility measurement and analysis have attracted attention from the automobile industry for years, but an objective test procedure is yet to be established. The paper proposes a method of using a newly-designed mass dummy for benchmarking measurement, as the first step towards the goal of establishing a metric of human occupant vibration comfort. Two seats are tested and the results are presented. Discussions are directed toward interpreting the data measured from a rigid mass, instead of a human seat occupant. The capability of distinguishing the transmissibility differences between seats shows the possibility of using a rigid mass dummy to assess the seat vibration comfort quality. Further work needs to be done to correlate the dummy measurement data to human occupant measurement data and to establish the seat vibration comfort metric based on the correlation. This paper is the first of a series of publications on vibration comfort development at Lear Seating Corporation.