## 3 Results and Discussion
### Pallet vs. Forklift  
The mean peak acceleration for impacts measured on both the pallet and the forklift were compared via the [PERSON]'s pairwise comparison. The differences were evaluated according to the main effects of the study (Table 6). Significant differences were found in the acceleration levels between the pallet and forklift. There is a pallet acceleration increase of 17-21% when heavier forklift trucks are used to impact the pallet. Comparisons made by pallet design show significant differences between the acceleration responses measured in the pallet and the forklift. However, there is no difference between the pallet designs, which show an increase of 10 G in the pallet when compared to the acceleration response measured in the forklift. The acceleration responses measured on the forklift and the pallet significantly change with different entry speeds. This acceleration difference ranges from 8 G-12 G.  
When varying the top loads, there are significant differences between the peak acceleration responses measured in the pallet and the forklift. However, the 680 kg and 1134 kg top loads show a 9 G difference when comparing pallet to forklift. There is a 12 G difference in the acceleration measurements when a 227 kg top load is used. The acceleration of the pallet is approximately 4.4 times greater than the forklift. However, the acceleration peak increase was not the same at different types of forklifts, presumably due to the virion in forklift mass and operator manoeuvre styles. Variations in the mass of the forklift types and operator error may explain these scenarios. The impact durations for pallet and forklift are consistent, ranging from 10 ms-12 ms. However, extended durations were obtained with the reach truck, which averaged 20 ms. Figure 8 contains the shock curve for the same impact event, as measured on the pallet (3D15) and the forklift (3X90). Acceleration measured on the forklift for this event was 4.6 G. The acceleration measured on the pallet was 8.6 G (Figure 8). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Peak Acceleration Mean**} \\  & & \multicolumn{4}{c}{**(G)**} \\ \hline
**Factor** & **Level** & **Forklift** & **Pallet** & **Difference (G)** & _p-Value_ \\ \hline \multirow{3}{*}{Forklift Type} & Reach & 2.81 (44.5) & 10.83 (50.8) & 8.03 & 0.0001 \\  & Electric & 2.80 (37.5) & 12.97 (28.9) & 10.17 & 0.0001 \\  & Gas & 3.35 (29.6) & 15.64 (33.8) & 12.30 & 0.0001 \\ \hline \multirow{3}{*}{Pallet Design} & Wood & 3.33 (37.2) & 13.46 (39.2) & 10.13 & 0.0001 \\  & Plastic & 2.64 (33.3) & 12.84 (41.1) & 10.20 & 0.0001 \\ \hline \multirow{3}{*}{Entry Speed (mph)} & 0.5 & 2.42 (34.3) & 10.42 (41.7) & 8.00 & 0.0001 \\  & 1 & 3.54 (31.4) & 15.87 (29.6) & 12.33 & 0.0001 \\ \hline \multirow{3}{*}{Top Load (lbs)} & 500 & 2.68 (36.6) & 14.68 (39.1) & 12.00 & 0.0001 \\  & 1500 & 2.83 (38.5) & 12.02 (43.8) & 9.19 & 0.0001 \\ \cline{1-1}  & 2500 & 3.44 (33.7) & 12.75 (34.6) & 9.31 & 0.0001 \\ \hline \hline \end{tabular}  
* Numbers in parentheses refer to coefficient of variation.  
\end{table} 
Table 6: T Pairwise Comparisons for Peak Acceleration Mean: Pallet vs Forklift *. The results obtained in this study were compared to the results of [PERSON] et al. [21] who measured the shock response on a hardwood pallet when impacted by a forklift truck. The authors used similar levels of pallet top loads (227 kg and 680 kg) measuring the shock response in the direction of impact. The duration of the events found with this research is consistent with the levels obtained by [PERSON] et al. [22], which ranged from 8.1 ms to 12.2 ms. However, impacts on the 680 kg, the severe impact condition for [PERSON] et al. [22], showed a significant reduction in event duration (4.9 ms). The duration response for the events measured by [PERSON] et al. [21] seems to be affected by the different conditions in their experimental design, which were not observed for this research.