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.
