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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Investigation into Pallet Durability Throughout the Hazards that Pallets Experience During Regular Use and Handling

Masis Ulloa, Jorge Andres 09 February 2022 (has links)
Pallet durability is a key characteristic with significant impact on a company's supply chain. Physical durability is defined as the number of trips that the pallet will accomplish before requiring repairs. Numerous studies have focused on understanding how durability is affected by different pallet components and warehouse environment characteristics. The VPI FasTrack is a testing sequence created to predict the performance of a pallet in a warehouse environment through different handling modes. However, this simulation has not been updated since its creation in 1993; therefore, a revision is needed to make it more closely reflect the behavior of a pallet in terms of durability. The objective of the current research was to investigate the ability of the FasTrack procedure to replicate the damages caused by material handling and storage systems in modern warehouses. This investigation was conducted through visual inspections of the damages seen on pallets used in the field, and pallets tested with FasTrack. The results of this study show the differences between the simulation-tested pallets and those from the field. The FasTrack simulation focuses heavily on top lead deckboard and stringer damage. The occurrence of damage modes such as splits and missing wood, were identified for these components. It was found that most of the damages from this simulation are created due to forklift handling. Because of substantial forklift handling damages, an experimental design was developed to investigate the effects of entry speed, payload, forklift type, and pallet design on the stresses exerted on a pallet, measured in terms of peak acceleration. The factors with the greatest effect on forklift peak acceleration and pallet peak acceleration were identified. The research shows that the acceleration in the pallet is approximately 4.4 times greater than the acceleration recorded in the forklift; however, the model of pallet acceleration based on forklift acceleration as a predictor shows poor performance. Different modifications to FasTrack are proposed according to the findings of this research. It is advised that they continue the FasTrack procedure past the point of repairable damage in a pallet, which is the usual practice when pallets are handled in the field. Further investigation of steps such as the flow rack and the stack storage are proposed, due to their low damage output during the simulation. The experimental design also showed that different damage severity levels from the FasTrack simulation are possible with variations in top load and entry speed. These changes could improve the ability of the VPI FasTrack to replicate the damages that pallets experience in the field. / Master of Science / Pallet durability refers to the number of uses that can be expected from a pallet before it needs to be repaired. Durability is an important performance characteristic, with a direct effect on the supply chain for any company. By further understanding how the warehouse environment and material handling systems affect pallet durability, companies can significantly reduce costs and improve their supply chain operations. The FasTrack procedure was created to satisfy the need for an effective durability simulation procedure. Created in 1993, FasTrack features different handling modes and interactions with handling equipment to reproduce the damages that a pallet could suffer in a real warehouse environment. However, warehouse environments have changed since the creation of FasTrack, which makes it important to assess the performance of this procedure in predicting pallet durability. The goal of this research was to investigate the ability of the FasTrack procedure to replicate the damages caused by material handling and storage systems in modern warehouses. This study was conducted through visual inspection of damaged locations, damage types, and damage severity levels for pallets used in the field and for pallets tested with FasTrack. The results obtained show differences between FasTrack and the field. The damage distribution in FasTrack for components of the pallet such as stringers and top lead deckboard is significantly higher than that measured in the field. The interaction of the pallet with the forklift could explain common damage modes, such as splits and missing wood, which were identified as the most damaged components in the pallets. An experimental design was developed to investigate the effects of entry speed, top load, forklift type, and pallet design on the stresses produced during interactions between forklifts and pallets. This interaction was measured in terms of horizontal shock impact acceleration. The most influential factors for forklift and pallet peak accelerations were identified with this study. An opportunity to predict pallet acceleration with forklift acceleration was identified, which could allow further investigation of the FasTrack simulation compared to the field. The results of the investigation show that FasTrack does not accurately reproduce the damages that pallets experience in the field. To improve the performance of the VPI FasTrack, the research proposes a revision of the steps during which damage output is low, such as the flow rack and the stack storage. The experimental design identified forklift entry speed and top load on the pallet as potential variables that could be customized in FasTrack, reflecting different severity levels based on a customer's unique environment characteristics. These changes could improve the correlation of the damages seen from the FasTrack simulation and the field, which would grant the industry a more reliable prediction of pallet durability.
2

CAE systém EPLAN Electric P8 - tvorba výkresové dokumentace pro dálkové ovládání motorgenerátoru / CAE system EPLAN Electric P8 and design documentation

Měřínský, Jiří January 2010 (has links)
This Graduation Theses dissertate about a creation of a drawing documentation at the professional CAE EPLAN Electric P8 system. One original solution of a remote control and of motor-generator monitoring with a mobile phone, short SMS-aided in this case, was used as an example of the drawing documentation. As has allready been noted in previous Bachelor Thesis, this application can be use not only for a remote control of a motor-generator, but this solution is suitable for other electric devices too, which are out of reach of an attendance for example. In our case a generator with 6kVA power is concerned with rated output voltage 230Vac and rated current 25A. The system of a remote control has the advantage that it is created from standard components (electric instruments, a PLC – programmable automat, a GSM modem, an operating panel and the respective program in the PLC).

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