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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

Extinction Coefficient Measurement Comparison of Tungsten Powder Clouds

Grenley, Spencer P 01 September 2021 (has links) (PDF)
All materials in dust form pose an increased risk of accidental deflagration, or explosion. For workplace safety, this risk of deflagration for a solid particulate sample is characterized through specialized dust explosibility testing systems. These systems disperse a cloud of powder inside a spherical chamber via a pressure gradient, where a timed ignition occurs. The accuracy of measurements taken during this process are predicated upon the assumption that the cloud of powder is uniformly distributed during the ignition period. Metal additive manufacturing (AM) is a rapidly expanding technology that, in some cases, involves heavy metal powders that do not disperse well in standard explosibility testing vessels. Consequently, there is a need to validate explosibility data for heavy metal powder blends to ensure that the dust sample is adequately dispersed in the chamber at the time of ignition. This thesis provides a method for employing optical dust probes to determine the concentration of a tungsten metal AM powder cloud inside an enclosed vessel. Optical dust probes are devices that measure light transmission through an attenuating medium, in this case a cloud of powder, and utilize Bouguer-Beer-Lambert (BBL) law to determine the concentration of particles. This thesis summarizes and synthesizes the assumptions and limitations of BBL law when used with optical dust probes, drawing from multiple published works with varying applications. The bounds of the average extinction efficiency are discussed, especially with respect to when the extinction paradox can be applied. Ultimately, it is determined that the BBL law can only be applied in this study to determine extinction coefficients, and that calculating a specific mass concentration value is theoretically misguided without specific modifications to the experimental setup. The extinction coefficients measured via an optical dust probe and a separate image analysis method are compared. Although no correlation could be established due to the limitations of this experimental setup, specific modifications are suggested that would enable this methodology to be used in future applications.
2

Výroba dílů s odlehčenou strukturou a topologickou optimalizací / Manufacturing of parts with lattice structure and topological optimization

Pospíšil, Jan January 2020 (has links)
This thesis deals vith the design of welding torch holder using topology optimization and lattice structure. The objective of this thesis is gaining knowledge about topology optimization in different software and aplication of methods to that part. Conclusion of this thesis is about production design and economic evaluation.
3

Karakterizacija proizvodnih parametara alata za utiskivanje izrađenih tehnikom 3D štampe / Characterisation of manufacturing parameters of embossing dies produced by 3D printing technique

Banjanin Bojan 09 November 2018 (has links)
<p>U disertaciji su predstavljena istraživanja uticajnih parametara u procesu izrade alata za utiskivanje tehnikom aditivne proizvodnje, tačnije tehnikom deponovanja istopljenog materijala (FDM). Izrađena je kontrolna grupa alata za utiskivanje konvencionalnom tehnikom hemijskog nagrizanja i SLA tehnikom 3D štampe. Cilj istraživanja je definisanje optimalnih procesnih parametara izrade alata za<br />utiskivanje FDM tehnikom štampe. Ustanovljena je metodologija za karakterizaciju proizvodnih parametara koja se može primeniti na ostale tehnike aditivne proizvodnje. Analizom dobijenih rezultata i zaključaka istraživanja ustanovljena su ograničenja i mogućnosti zamene konvencionalnih alata za utiskivanje alatima izrađenim tehnikama 3D štampe.</p> / <p>The study of the influencing parameters in the production process of embossing dies using Fused Deposition Modelling (FDM) additive manufacturing technique, was investigated in this dissertation. Embossing dies, produced using conventional chemical etching and vat photopolymerization technique, were developed as a control group. This research aims to define the optimal process parameters of Fused Deposition Modelling (FDM) in embossing dies manufacturing. A new methodology for the characterisation of production parameters, which can be applied to other additive production techniques, has been established. By analysing the results and the conclusions of this research, the possibility of replacing<br />conventional embossing dies produced using 3D printing techniques has been established as well as its limitations.</p>

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