Evaluation of subjective responses to whole-body vibration exposure: Effect of frequency content

The relationship between the subjective ride comfort in a vehicle seat and whole-body vibration can be modeled using frequency weightings and rms averaging as specified in ISO 2631-1. If two vibrating environments have the same frequency-weighted rms acceleration value using this method, it is assumed that the two environments would have the same degree of discomfort. In recent years, it has been found that when subjects are exposed to random whole-body vibration, even with the same frequency-weighted rms acceleration signals according to the ISO 2631-1 standard which consists of different frequency spectra will elicit different degree of comfort. From the viewpoint of this result, it is doubtful whether frequency-weighting based on ISO 2631-1 is appropriate for such vibrations.In this paper, the alternative approach which Miwa's proposed VG method modified was examined. The following conclusion was suggested: VGt value which was obtained by the alternative approach seems to be appropriate from random vibrations which have same frequency-weighted rms acceleration with different frequency components. The alternative approach based on the VG method has wider applicability but requires more researches.Relevance to industryFew researchers have demonstrated the problem of the frequency-weighting method of the ISO 2631-1 standard. This may have implications to current used ISO frequency-weighting method for evaluating the comfort on the vehicle seats. Therefore, comfortable evaluation of the vehicle seats vibration by the amount of frequency-weighted rms acceleration values obtained by the ISO 2631-1 standard takes cautions.