Browsing by Author "Alvarez Valverde, Mary Paz"

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    Finite Element Modeling of Plastic Pails when Interacting with Wooden Pallets
    Alvarez Valverde, Mary Paz (Virginia Tech, 2024-06-04)
    The physical supply chain relies on three components to transport products: the pallet, the package, and unit load stabilizers. The interactions between these three components can be investigated to understand the relationship between them to find potential optimization strategies. The relationship between corrugated boxes and pallets have been previously investigated and have found that the relationship can be used to reduce the quantity of material used in unit loads and can also reduce the cost per unit load if the package and pallet are designed using a systems approach. Although corrugated boxes are a common form of packaging, plastic pails are also used in packaging for liquids and powders, but they have not been previously investigated. To understand the interactions between the wooden pallet and plastic pails, physical tests were conducted and then used to create and validate a finite element model. The experiments were carried out in three phases. The first phase included physical testing of plastic pails where the deckboard gap and overhang support conditions would be isolated by using a rigid deckboard scenario. The second phase also used physical tests to investigate plastic pails but instead used flexible deckboards and used an overhang support condition and a 3.5 in. gap support condition. The third phase of experiments would develop and validate a finite element model to further understand the impact of deckboard gaps and overhang depending on the location of the gap. Previous physical experiments were used to create and validate the finite element model. Nonlinear eigen buckling analysis was used to model the plastic pail buckling failure that was seen in physical testing. The model based on the physical experiments was able to predict the behavior of the plastic pail within a range of 5-12% variation with higher variation being introduced when the flexible deckboard is introduced. The finite element model was then used to model a range of deckboard gap sizes and overhang sizes as well as different locations for deckboard gaps. The results of the experiments indicate that the percent of pail perimeter that is supported directly on the pallet impacts the compression strength of the plastic pail. Decreasing the quantity of support decreases the compression strength of the plastic pail in a linear pattern. The location of the deckboard gap also influenced the compression strength because of the quantity of pail being supported being altered. The results of the experiments can be used by industry members to provide guidelines on unit load design to prevent plastic pail failure. Industry members can also use the results as a baseline investigation and further the finite element model by incorporating their own plastic pail design.
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    Investigation and Analysis of the Effect of Industrial Drums and Plastic Pails on Wooden Pallets throughout the Supply Chain
    Alvarez Valverde, Mary Paz (Virginia Tech, 2021-10-05)
    In the supply chain there are three components: transportation method, the pallet, and the packaging. Traditionally, there has been a poor understanding of the way that pallet design can impact the supply chain. There are historical studies that illustrate the importance of investigating how box stacking pattern, unit load type, unit load size, and containment can impact the pallet's performance. However, there have been no studies that have investigated the impact of drums and plastic pails on pallet performance. The goal of the current research study was to investigate how plastic pails and drums affect pallet bending and the distribution of the pressure on the top surface of the pallet. The investigation was conducted using four different support conditions commonly found in warehouses: racking across the width and length, single stacking, and double stacking. The results of the investigation indicated that for most support conditions, loading the pallet with plastic pails or drums results in a significant reduction in deflection when compared to a uniformly distributed load. The maximum observed reduction in pallet deflection was 85% when testing with drums in the double stack condition and 89% when testing with plastic pails in the single stack condition. The large reductions in deflection could indicate that the pallets were over-designed for the unit load that they were supporting. Pressure mat distribution images collected during the experiment display a load bridging effect where the stress of the drums and pails are redistributed to the supported sides of the pallet. The data also show that drums made of different materials distribute the pressure onto the pallet in a significantly different manner.