There are 513 million new wooden pallets produced every year in the United States, most of which are purposely built for specific applications. Currently, most wooden pallets are designed with the assumption that they will carry a uniformly distributed, flexible load. However, it has been observed by many researchers that most loads carried by pallets are discrete loads where the interactions between packages cause pressure redistribution defined as load bridging. The load bridging phenomenon has been extensively studied for corrugated boxes, and it has been found that the deflection of the pallet is highly dependent on the number, size and type of corrugated boxes and the design of the pallet used. Although pails are an essential packaging solution used to transport smaller amounts of liquids (1–40 L), there is a lack of understanding about the effect of load bridging on unit loads of pails. The objective of this research was to understand the differences in pallet bending and pressure distribution across the top of the pallet when pallets are loaded with plastic pails compared with a flexible airbag. The results revealed that pallets deflect 32%–89% less when loaded with plastic pails. The load predominantly distributes down the bottom perimeter of the pail, indicating that the design of the bottom of the pail could have a major effect on pallet performance. The effect of plastic pails was dependent on pallet design, indicating that the stiffness of a pallet could have a major effect on load bridging experienced by plastic pails.

Palletized unit loads are composed of pallets, packages, and unit load stabilizers. The interactions between components are significant for designing efficient and sustainable pallets. Although there has been research on corrugated boxes, there is no research revolving around plastic pails. The objective of this study was to understand how plastic pails are affected by the pallet's top deckboard thickness and the effect of the pail's location on the pallet. The first phase of testing investigated the pail location effect in five different locations on a small-scale pallet segment. The second phase further investigated the two locations that had the best and worst performances in terms of pail strength. One additional location was chosen based on a previous study on corrugated boxes. It was found that the pallet's top deckboard thickness and the location of the pail both had significant impacts on pail deformation, pallet deflection, and pail compression strength. This study also indicated that symmetrical and asymmetrical loading created different trends when comparing pail deformation, pallet deformation, and pail compression strength. It was found that the thickness of the deckboards is relevant when investigating pail failure but the experiments were unable to find a consistent trend between pallet deflection and pail failure load. These factors can all be taken into account by unit load designers in order to create safe and sustainable pallets.

As an integral part of the supply chain, wooden pallets are produced in large quantities, with 849 million new and recycled wooden pallets being manufactured annually in the industry. Pallets are currently designed using a uniformly distributed load to determine the load capacity. This highly generalized approach often leads to overdesign and increased material utilization. Due to a phenomenon called load bridging, when discrete packages such as corrugated boxes or industrial drums are shipped on a pallet, the weight of the load tends to distribute unevenly. This can lead to an increased load capacity for the pallet. Industrial drums are commonly used to transport large amounts of liquids and chemicals; however, their load bridging effect has not been previously researched. The objective of this study was to investigate the effect of 55-gallon drums on the pressure distribution and deflection of stringer class wooden pallets using multiple support conditions and pallet designs. Results of the study indicated that loading pallets with drums significantly reduces the deflection of the pallet in all support conditions when compared to a uniformly distributed load. It was also observed that plastic and metal drums distributed their load to the pallets differently, which resulted in significantly different load bridging effects for each drum type.