Abstract:
This study focuses to certain elements of th
e Road-Vehicle-Load system which are responsible
for the inflicted damage to consignment during road transportation. Bruising injury depends on
the energy absorbed by the cargo. Distribution of the power spectral density (PSD) was used as
a measure of the vibration energy generated during transportation. “Poor” quality (IRI range 10
to 5) roads induce nearly four times severe damage than that induced by “fair” or “good” quality
roads (IRI range 3.5 to 2 or, 2 to 0.9). PSD of the generated vibration is relatively higher in the
critical frequency range below 10 Hz. In this frequency range, the rear side of the truck bed
indicates nearly a 10 times higher PSD compared to that of the front side of the truck. A higher
PSD distribution was also observed at tomatoes occupying higher layer levels in multi-layered
tomato columns. Higher PSD levels were observed at very poor quality roads even at lower
vehicle speeds. Fair quality roads also produced higher PSD levels, but when travelling at
higher speeds. In case of stacked cargo boxes, an increase in PSD level was observed with
stack height from the truck bed. Studies performed using the instrumented sphere reveals that,
among the positions of multilayered items within the cargo box, the position of the topmost item
registered highest PSD level. In addition, the top most item in multilayered cargo packages, has
freedom to move and resulting damage can be even higher. The PSD generated by the truck
has a good relationship to the quality of the road (judged by a panel in terms of PSR or IRI) and
the speed of the truck.
