The selection of different averaging approaches on whole-body vibration exposure levels of a driver utilising the ISO 2631-1 standard

Abstract

Limited research has been conducted on inconsistencies relating to whole-body vibration (WBV) field assessments. Therefore, this study aimed to investigate a certain possible contributor to inconsistencies in vibration assessment work, namely averaging intervals. To our knowledge, this was the first study investigating the effect of multiple averaging approaches on WBV results. WBV parameters were measured for a driver operating a vehicle on a preselected test route utilising ISO 2631-1:1997. This was achieved utilizing a Quest HavPro vibration monitor with a fitted tri-axial Integrated Circuit Piezoelectric (ICP) accelerometer pad mounted on the driver’s seat. Furthermore, in an attempt to decrease differences between observed WBV results, an outlier detection method, part of the STATA software package was utilised to clean the data. Statistical analyses included hypothesis testing in the form of one-way ANOVA and Kruskal-Wallis one-way analysis of variance by ranks to determine significant differences between integration intervals. Logged data time-series durations showed a W0 = 0.04, therefore indicating unequal variance. Omission of 60s from statistical analyses showed a W0 = 0.28. The observed difference occurs when data is averaged over longer intervals, resulting in portions of data not being reflected in the final dataset. In addition, frequency-weighted root mean squared acceleration results reflected significant differences between 1s, 10s, 30s, 60s and SLOW averaging approaches, while non-significant differences were observed for crest factors and instantaneous peak accelerations. Vibration Dose Value results reflected non-significant differences after omission of 60 second averaging interval data. Cleaned data showed significant differences between various averaging approaches as well as significant differences when compared with raw vibration data. The study therefore outlined certain inconsistencies pertaining to the selection of multiple integration intervals during the assessment of WBV exposure. Data filtering could not provide a conclusion on a suitable averaging period and as such, further research is required to determine the correct averaging interval to be used for WBV assessment.