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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

Mekaniska beräkningar av armeringstråd vid förläggning på högspänningskablar / Mechanical calculations of reinforcing wire upon the application on high voltage cables

Nilsson, Philip January 2014 (has links)
This thesis has taken place at ABB High Voltage Cables in Karlskrona and focuses on their reinforcement process (AR50) which reinforces the cable by application of reinforcement wires. The research is strictly limited to only the short period during the application of the wire on the cable and investigates stress differences in one reinforcing wire depending on cable - and wire dimensions as well as brake forces used in the production. The study follows a model - and theory development research process combined with a testing process to obtain the results. The study aims is to increase and expand ABB's knowledge about the reinforcing process that is used to strengthen and protect ABB’s all different high voltage cables together with a computational calculation model. The model is developed in the FEA (Finite Element Analysis) program ABAQUS through a dynamic explicit model. An explanation of how the calculation model has been built and the parameters used are described in this report. These parts then contribute to the outcome of the study which provides a sense that the brake force used in AR50’s reinforcement process does not need to be controlled with a high precision so long as it is large enough to hold the reinforcement wire stretched upon the application. The study also shows that different cable - and wire dimensions does not affect the stress levels somewhat significantly by reinforcing the process and that the nipple used in reinforcement process to press down the reinforcing wire on the cable is the main source that determines how the stress distribution looks like on the reinforcement wire. / Detta examensarbete har tagit plats på ABB High Voltage Cables i Karlskrona och fokuserar på deras armeringsprocess (AR50) som förstärker kabeln genom påläggning av armeringstrådar. Arbetet är starkt begränsat till enbart den korta perioden för själva påläggningen av tråden och undersöker spänningsskillnader i en armeringstråd beroende på olika kabel – och tråddimensioner samt bromskrafter som används i produktionen. Studien följer en modell – och teoriutvecklande forskningsprocess kombinerat med ett utprövande resultatbildande. Studiens syfte är att tillsammans med en beräkningsmodell öka och fördjupa ABBs kunskaper kring armeringstråden som idag används för att stärka och skydda ABBs alla olika högspänningskablar. Beräkningsmodellen tas fram i FEA (Finita Element Analys) prorammet ABAQUS genom en dynamisk explicit modell. En förklaring till hur beräkningsmodellen har byggts upp och vilka parametrar som används beskrivs i rapporten. Dessa delar bidrar sedan till resultatet i studien som ger en bild av att bromskraften som används i AR50s armeringsprocessen inte behöver kontrolleras med en hög precision så länge den är tillräckligt stor för att hålla armeringstråden sträckt vid påläggningen. Studien visar också att olika kabel – och tråddimensioner inte påverkar spänningsnivåerna något markant vid armeringsprocessen och att nippeln som används i armeringsprocesen för att trycka ner armeringstråden mot kabeln bestämmer hur spänningsbilden ser ut. / <p>This thesis is kept confidential</p>
2

Quality by design: improving pre-stressed reinforcement for concrete railroad ties via geometrical dimensioning and tolerancing

Haynes, Mark Davis January 1900 (has links)
Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Chih-Hang John Wu / Quality is a result of product design and production control. Product design must maximize the ability to function across variations in production and environment. Production control must monitor and maintain the key design characteristics necessary for the intended function. Failure to do so results in premature part failure and increased costs. This has occurred in the production of modern cross ties. By designing quality into the product and production process, performance is maximized. This research presents a methodology for incorporating quality into the product design and production process. For product design, a relationship between product performance and design parameters is established by modeling techniques. These models provide a means to redesign the product to maximize performance and to understand the sensitivity of the design to fluctuation in production and environment. These models also establish the key design parameters that are critical for sustaining quality. For production, a method of monitoring the key design parameters is presented that provides an affordable means of automated inspection. Automated inspection removes operator error from the inspection process and allows for greater sampling rates to be achieved. The methodology presented allows for a potential of 100% inspection to be achieved with minimal impact to production costs. The research is applied to the analysis and quality control of pre-stressing steel reinforcement for concrete cross-ties. This application provides an opportunity to test and verify the research findings on a real world problem. Novel automated 3D spatial analysis algorithms are presented. This research furthers the state of the art of performing Geometrical Dimensioning and Tolerancing (GD&T). A cost effective method of non-contact surface profiling was developed with high resolution and high density surface profiles. The combined research findings present a methodology of achieving quality by design.

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