## 5 Results and Discussion
### Unit Load Segment Results and Discussion
The larger boxes could have slight deformations in the experimental tests, changing the contact interactions; therefore, changing how the load is transferred to the pallet and ultimately affecting the pallet's deflection. Additionally, the use of no containment force in these experiments allowed the boxes to be freely displaced during the rotation generated through bending. This movement will be much more constrained in an actual unit load, given the use of containment mechanisms. By constraining the contact interactions, the contact interactions are more accurate in their prediction. Figure 10: Comparison of movement of unit load components under deflection for experimental (**left**) and finite element analysis (**right**) for two layers and (**a**) two columns, (**b**) three columns, and (**c**) four columns of packages. Images shown for the model (**left**) are colored based on deflection. Red equals large displacements, blue represents no movement. larger displacements, the behavior of the boxes will be closer to the other scenarios, and hence could be better simulated. For all the five scenarios where the unit loads had three or four columns, the model was capable of accurately predicting the deflection and the movement of the boxes. This movement is closely linked to their load bridging behavior. Figure 10b,c shows the behavior of the boxes in the experimental tests and in the FE simulation for the 3 \(\times\) 3 and 4 \(\times\) 3 units. Visually, this model reasonably replicates the box movement. The 3 \(\times\) 3 unit load shows a slight box rotation at the outer columns while the center column is displaced straight downwards. Although the boxes rotate, the model is capable of accurately predicting the pallet segment's deflection. The smaller rotation does not significantly affect the contact properties or cause any box deformation, as discussed for the two-column unit loads. The four-column unit load is also represented correctly in the model and shows high accuracy in the deflection results and in the visual inspection of box behavior. Small boxes kept their form, and the movements of these boxes were mostly along the y-axis, confirming the model's ability to represent the load bridging accurately. The model was able to simulate a unit load's bending accurately for three and four-column scenarios without requiring the further complexity that would be added by having to simulate corrugated panels and their potential buckling. Being this a friction driven model, changing the pallet analogue material from the selected PMMA to a more common material such as a wooden top deck would undoubtedly change the interaction mechanics. The higher friction resistance from the wood and corrugated board interface would restrict the box's displacement and would affect how the payload is displaced. The presented model can be extended to fully characterize this frictional effect. Comparing the results when using a non-uniform structure to carry the payload, such as GMA pallets with stringer boards and partial top deck coverage, should not change the results of the study. This model studies the two-dimensional response on pallet bending and previous studies on load bridging using full unit loads have shown a uniform deflection response [20, 21, 23] that could be accurately represented as a two-dimensional model. Using materials with different stiffnesses will change the absolute deflection experienced by the board. Load bridging emphasis has been on the ratio of change from one payload to another, while maintaining the pallet, this reinforces the benefit of studying it by using a uniform pallet analogue [19]. Previous research has shed a light on the relationship between box size and how it affects pallet deflection [4, 15, 19, 20, 21, 22]. The major trend in their conclusions was the evidence that as package size decreased, deflection increased.