Stress Analysis on Palletized Unit-load of Various Pallet Stacking Patterns in Corrugated Packages

In current scenario of supply chains, the palletized unit-load (PUL) is a major form of storage and distribution for packaged products. The packaging materials used for the unitization of PUL products are mainly corrugated packages and the stability of the unit-load is primarily related to the compressive strength of the corrugated package. Studies dealing with the interaction between the pallet and stacked packages have been conducted since long time; however, the results of studies dealing with the stability and stress distribution of PUL according to the pallet stacking pattern (PSP) are insufficient. In this study, the stability and design factors of PUL were analyzed through a stress analysis using block, alternate-row, and pinwheel PSP as targets. As a result of the experiment and finite element analysis (FEA), the stress acting on the bottom-surface of the lowest-layer packages was mainly concentrated near the four vertical edges in the block PSP. However, in the alternate-row and pinwheel PSP, where the upper and lower corrugated packages were interlocked, the stress distribution tendency toward the vertical panels appeared owing to the distribution of the stacking load. In addition, the maximum stress reduction and stress distribution effects of shrink-wrap packaging were also the most significant in the block PSP. Considering only the stability and strength of the PUL of the corrugated packages, a mixed pattern of blocks in the lower layer and interlock PSP in the upper part is considered effective.