LABORATORY TESTING OF OPERATOR SEAT VIBRATION WITH 37 SUBJECTS—CRITICAL COMMENT ON ISO/DIS 7096
✍ Scribed by B. Hinz; G. Menzel; R. Blüthner; H. Seidel
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 199 KB
- Volume
- 215
- Category
- Article
- ISSN
- 0022-460X
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✦ Synopsis
The operators of earth moving machinery are often exposed to a low frequency vibration environment caused by the movement of vehicles over uneven ground and the task carried out. The seat constitutes the last state of suspension before the driver. The efficiency of attenuation under consideration of the best design practice today is the basis for the revision of ISO 7096 for the testing seats for earth moving machinery. This standard requires the participation of two subjects with different body masses (52-55 kg; 98-103 kg). The aim of the study was to investigate (1) the extent and the influence of individual variability and posture change on the result of seat tests, and (2) the possibility of deducing representative results for the user population. 37 male subjects took part in the experimental investigations. They were exposed in three postures for 67 s to three acceleration signals in a vertical direction corresponding to the spectral classes (EM2, EM5, EM6) in ISO/DIS 7096 on two commercial suspension seats. The vertical accelerations were measured at the seat basis and at the interface between seat cushion and subject. The results of the analysis of variance show a significant influence of exposure, type of seat, and interactions exposure-by-posture, exposure-by-type of seat, and posture-by-type of seat on the SEAT factor. Simple and multiple regression analyses were applied in order to test the predictability of the seat factor (SEAT) by anthropometric variables. The conclusions were drawn that the seat testing could be improved by (1) selecting subjects according to the 5th and 95th percentile masses of the population of vehicle or machinery users for which the seat is intended (ISO 10326), instead of fixed masses (ISO 7096), (2) considering other anthropometric parameters for the selection like the body height and body mass supported by the seat, and (3) the inclusion of several subjects near the 50th percentile in order to assess the variability of the SEAT factor.