Browsing by Author "Molina, Eduardo"

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    Development of a Friction-Driven Finite Element Model to Simulate the Load Bridging Effect of Unit Loads Stored in Warehouse Racks
    Molina, Eduardo; Horvath, Laszlo; West, Robert L. (MDPI, 2021-03-29)
    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.
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    Development of a Gaussian Process Model as a Surrogate to Study Load Bridging Performance in Racked Pallets
    Molina, Eduardo; Horvath, Laszlo (MDPI, 2021-12-14)
    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 pallets can be optimized and raw material consumption reduced. The objective of this study was to develop a full description of how such payload characteristics affect load bridging on unit loads of stacked corrugated boxes on warehouse racking support. To achieve this goal, the authors expanded on a previously developed finite element model of a simplified unit load segment and conducted a study to screen for the significant factors and interactions. Subsequently, a Gaussian process (GP) regression model was developed to efficiently and accurately replicate the simulation model. Using this GP model, a quantification of the effects and interactions of all the identified significant factors was provided. With this information, packaging designers and researchers can engineer unit loads that consider the effect of the relevant design variables and their impact on pallet performance. Such a model has not been previously developed and can potentially reduce packaging materials’ costs.
  • Predicting the Effect of Pallet Overhang on the Box Compression Strength
    Kim, Saewhan; Horvath, Laszlo; Molina, Eduardo; Frank, Benjamin; Johnson, Steven; Johnson, Alonda (2023)
    Unit loads, consisting of pallets and corrugated boxes, are one of the primary forms of storage and distribution of packaged products. The corrugated box’s compression strength can easily be affected by environmental parameters, such as pallet overhang, which reduce a box’s effective compression strength. The effects of overhang on box compression strength have been investigated by multiple researchers, but each previous study used its own unique set of different sizes of boxes made from different materials, limiting the broad comparability of the results and challenging strong statistical analysis. The current study, performed on behalf of the Fibre Box Association and ICPF, aimed to investigate the effects of pallet overhang on box compression strength using four different sizes of corrugated boxes, made from two different board combinations, in order to compare existing values in the Fibre Box Handbook, and potentially explore the possibility of developing a more universal model for predicting the effects of pallet overhang. The four sizes of boxes, for each nominal 32 ECT C-flute and nominal 48 ECT BC-flute corrugated materials, were examined in over a dozen single-side overhang configurations and five adjacent-side overhang scenarios. Compression tests were conducted in compliance with the TAPPI 804 standard. A range of multiple linear and nonlinear regression models based on these test results were developed for this study. These models provide the estimated change in a box’s compression strength due to any overhang, compared to a no-overhang scenario, by percentage. As expected from earlier work, effective box compression strength decreases as the magnitude of overhang increases. Significant differences were found when the same overhang was investigated on the width versus the length side of the boxes. It was also observed that the magnitude of the adjacent-side overhang effect on box compression strength is not simply related to the combination of short and long sides’ overhang effects, but it has a unique effect that is most likely related to the loss of additional box corner support as compared to single side box overhang. The box size relative to the amount of overhang was also a statistically significant factor affecting effective box compression strength in the tested overhang scenarios. This work also indicated the need for further research refining the first-order model and extending it to other materials, box sizes, and box aspect ratios.