Development of a Friction-Driven Finite Element Model to Simulate the Load Bridging Effect of Unit Loads Stored in Warehouse Racks

Abstract

Current pallet design methodology frequently underestimates the load capacity of the pallet by assuming the payload is uniformly distributed and flexible. By considering the effect of payload characteristics and their interactions during pallet design, the structure of the pallets can be optimized, and raw material consumption reduced. The objective of this study was to develop and validate a finite element model capable of simulating the bending of a generic pallet while supporting a payload made of corrugated boxes and stored on a warehouse load beam rack. The model was generalized in order to maximize its applicability in unit load design. Using a two-dimensional, nonlinear, implicit dynamic model, it allowed for the evaluation of the effect of different payload configurations on the pallet bending response. The model accurately predicted the deflection of the pallet segment and the movement of the packages for a unit load segment with three or four columns of boxes supported in a warehouse rack support. Further refinement of the model would be required to predict the behavior of unit loads carrying larger boxes. The model presented provides an efficient solution to the study of the affecting factors to ultimately optimize pallet design. Such a model has not been previously developed. The model successfully acts as a tool to study and predict the load bridging performance of unit loads requiring only widely available input data, therefore providing a general solution.

Development of a Gaussian Process Model as a Surrogate to Study Load Bridging Performance in Racked Pallets

“…A complete, comprehensive knowledge of the load bridging effect factors is not currently available. This paper continues the research based on the model developed by Molina, Horvath, and West [20].…”

“…The finite element model of the unit load segment used in this paper was a twodimensional implicit dynamic model presented by Molina et al [20]. In it, a segment of a unit load, supported on a warehouse storage racking condition across its width, was simulated.…”

“…This model provided an average prediction accuracy of 8% for unit load segments with three or more columns of packages. Molina et al [20] fully describe the finite element model formulation.…”

“…Figure 2 shows the unit load segment replicated, graphically depicting each factor. To capture the effects of these variables, values for the study were determined from the trends observed during the model development process in [20]. For the screening design, the unit load segments created consisted of three and five columns, and three and five layers.…”

“…Han et al [19] developed a finite element model to predict the deformation of pallet top deck boards under nonuniform load applications, but this only has limited application to rigid loads. Molina, Horvath, and West [20] presented a model simulating the bending behavior of a simplified unit load segment using an implicit dynamic, two-dimensional finite element analysis approach. Unlike previous approaches, this model provides a method to generically analyze a unit load when stored on warehouse rack beam support in order to determine the predicted level of load bridging for the specific load characteristics.…”