• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 50
  • 28
  • 27
  • 3
  • 3
  • 1
  • 1
  • Tagged with
  • 126
  • 41
  • 27
  • 25
  • 24
  • 23
  • 18
  • 17
  • 15
  • 14
  • 14
  • 13
  • 13
  • 12
  • 11
  • 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.
71

Modeling and analysis of a heat transport transient test facility for space nuclear systems

Wheeler, Adam (Adam Richard) 20 March 2013 (has links)
The purpose of this thesis is to design a robust test facility for a small space nuclear power system and model its physical behavior under different scenarios. The test facility will be used to simulate a 1-10kWe nuclear reactor, its electrical generation, and heat removal capabilities. This simulator will be used to explore, test and understand the steady-state and transient operation capabilities of small space nuclear power systems. Currently, the system is planned to operate on a variable, electrical heat source directly connected to heat pipes. The heat pipes are to be stainless steel with a water working fluid. These heat pipes will then be connected to a power conversion simulator or actual power conversion technologies. The power conversion simulator is connected to a radiator using a water based heat pipe network using fins and connecting plates in a cylindrical geometry. Modeling of the facility was performed using two different analysis programs, STELLA and SolidWorks. STELLA was used as a lumped sum heat transport code, and SolidWorks was used as a more accurate system to verify the validity of STELLA's results. Both programs were used to analyze startup, heat pipe failures, and loss of power conversion with the end goal of finding safe operational transient scenarios for the transient test facility. / Graduation date: 2013
72

Selective laser sintering and post-processing of fully ferrous components

Vallabhajosyula, Phani Charana Devi 08 June 2011 (has links)
Indirect additive processing of ferrous metals offers the potential to freeform fabricate parts with good surface finish and minimal dimensional variation from the computer solid model. The approach described here is to mix a ferrous powder with a transient binder followed by selective laser sintering (SLS) in a commercial polymer machine to create a “green” part. This part is post-processed to burn off the transient binder and to infiltrate the porous structure with a lower melting point metal/alloy. Commercially available SLSed ferrous components contain copper-based infiltrant in a ferrous preform. The choice of copper alloy infiltrant has led to inferior mechanical properties of these components limiting their use in many non-injection-molding structural applications, particularly at elevated temperature. In the present work, an attempt has been made to replace the copper-based infiltrant considering cast iron as a potential infiltrant because of its fluidity, hardness and stability at comparatively high temperature. A critical consideration is loss of part structural integrity by over-melting after infiltration as chemical diffusion of alloying elements, principally carbon, occurs resulting in a decrease in the melting temperature of tool steel preform. A predictive model was developed which defines the degree of success for infiltration based on final part geometry and depending on the relative density of the preform and infiltration temperature. The processing regime is defined as a function of controllable process parameters. An experimental program was undertaken using commercially available LaserForm[superscript tm] A6 tool steel that was infiltrated with ASTM A532 white cast iron. Guided by Ashby densification maps, pre-sintering of the A6 tool steel SLS part was performed to increase the part initial relative density prior to infiltration. The final infiltrated parts were analyzed for geometry, microstructure and hardness. The model may be extended to other ferrous powder and infiltrant compositions in an effort to optimize the properties and utility of the final infiltrated part. / text
73

The design and development of a vehicle chassis for a Formula SAE competition car / Izak Johannes Fourie

Fourie, Izak Johannes January 2014 (has links)
The Formula SAE is a student based competition organised by SAE International where engineering students from a university design, develop and test a formula-style race car prototype to compete against other universities. The competition car needs to satisfy the competition rules set out by the organisers. The competition strives to stimulate original, creative problem solving together with innovative engineering design practices. In any race environment, the primary goal is always to be as competitive as possible. Due to the competitive nature of motor sport, vehicle components need to withstand various and severe stresses. The components of a race car vehicle are responsible for the vehicle’s handling characteristics and reliability. The chassis is a crucial and integral component of a Formula SAE competition car, primarily responsible for the vehicle’s performance characteristics. The chassis is the structural component that accommodates all the other components. A Formula SAE chassis is a structure that requires high torsional stiffness, low weight as well as the necessary strength properties. In this study, multiple Formula SAE chassis were designed and developed using computer aided design software. Each concept’s torsional stiffness, weight and strength properties were tested using finite element analysis software. The different concepts consisted of different design techniques and applications. All the concepts were analysed and assessed, leading to the identification of an acceptable prototype. The prototype was manufactured for experimental tests. The designed chassis complied with the Formula SAE rules and regulations. The weight, torsional stiffness and strength characteristics of the designed chassis frame were also favourable compared to accepted standards for Formula SAE chassis frames. The manufactured chassis was prepared for experimental tests in order to validate the simulation results produced by the finite element analysis. The torsional stiffness, weight and strength were experimentally determined and the results were compared with the corresponding simulations results. The comparison of the experimental and simulated results enabled the validation of the finite element analysis software. The study draws conclusions about the use of computer aided design and finite element analysis software as a design tool for the development of a Formula SAE chassis. Closure about the study is provided with general conclusions, recommendations and research possibilities for future studies. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014
74

Design and manufacturing of SLM printed tooling for plastic injection molding

Ting, Huang, Daniel, Nordqvist January 2021 (has links)
The thesis work is to show that the use of SLM (Additive Manufacturing) compared with the traditional process to make injection molds will have advantages in design, especially in waterways.  This thesis work gives seven different versions of design applied to the SLM method to analyze and compare them in Solidworks® and Moldflow® to figure out what design is suitable for the SLM method. Through analysis of different versions, the finding of this thesis work is that the conformal waterway of design and lighter but stead structure in the SLM method causes the SLM molds' cooling performance to be almost 15% better than the conventional way and shorten the production time by 18% per product. Based on the advantages of the SLM method in cooling system design and structure optimization, the company can use the SLM method in the production process to improve economic and environmental benefits.
75

Vlastnosti fraktálních kapacitorů / Fractal capacitors properties

Chvíla, Ladislav January 2012 (has links)
This work is focused on computer simulations of fractal capacitors. The geometry of capacitors and its influence is investigated. Simulations are realized in programs Matlab, SolidWorks and Comsol Multiphysics. There are also several specific examples of different geometrics of capacitors their comparisons and assessment.
76

Spínací mechanismus ve výkonovém jističi / Switching mechanism in the molded case circuit breaker

Mejzlík, Tomáš January 2014 (has links)
This paper deals with mechanical switch in circuit breaker designed for low voltage. The goal of this thesis was to analyze switching mechanism both theoretically and practically. Theoretical analysis consist of study different types of switching mechanism and analytical calculations of acceleration speed and trajectory. Practical analysis has been made taking a video with high speed camera of real switching mechanism of a circuit breaker and software analysis of the data. The next part of a thesis is about 3D modeling, animating and simulating of a switchgear switching mechanism.
77

Návrh nové technologie výroby rotační součásti / A new production technology of a rotational part

Sychra, Jiří January 2016 (has links)
This master’s thesis is focused on a new production technology of a rotational part. The SolidWorks software was used for create the component design. According to the proposed models, CNC program using parametric programming using mathematical functions was created in the CNC Syntax Editor Free Edition program. The final step was the experimental verification of the functionality and components compared with other type and the economical evaluation of manufactured components.
78

Konceptframtagning av ett verktyg för montage av spantring på pressvals / Development of a concept for a tool to mount frame rings on a press roll

Amoev, Edward, Sagir, Ozan January 2022 (has links)
Detta projekt utfördes på uppdrag av Valmet AB på dess anläggning belägen i Sundsvall. Valmet är ett företag som är ledande inom pappersmassaindustrin och utvecklar maskiner samt utrustning inom massa-, pappers- och energiindustrin. En av dessa maskiner är TwinRoll pressen som detta examensarbete handlar om.  En del av pappersmassaindustrin inkluderar rengöring av massa. För detta används stora maskiner som kontinuerligt pressar smutsig vätska ur massan med hjälp av pressvalsar. På valsarna sitter en detalj vilket är betitlad som mantelsektioner och består av flertal spantringar. I detta arbete undersöks dessa mantelsektioner och dess produktionsmetod åt företaget Valmet.     Arbetets syfte var att framta ett koncept för ett verktyg som ska kunna underlätta montering av spantringarna som sitter på pressvalsen. Med framtaget koncept kan de svetsade mantelsektioner som tillverkas, ersättas av enbart spantringar som direkt monteras på valsen, vilket innebär att de istället för påsvetsning krymps på konstruktionen. Genom detta krävs inget mellansteg vid montering och det sparas både tid och pengar.   Studiens mål har varit att generera ett koncept som förändrar dagens produktionsmetod genom att effektivisera den med en praktisk samt kostnadseffektiv lösning.  Resultatet av examensarbetet visar ett konceptuellt verktyg i form av ett hydrauliskt gripdon vilket uppfyller kraven som författarna har ställt sig inför. Studien presenterar även en vidare utveckling av verktyget som går att implementera i företaget.
79

Låsförband mellan dörr och karm

Persson, Stina, Pihlblad, Johan January 2023 (has links)
This bachelor’s degree project that includes 15 credits at Mälardalens University has been carried out at 50% for 20 weeks, spring semester 2023.The locking principle between door and frame has for a long time been unchanged. The report describes the workflow during the project where the goal is to generate innovative concepts on different ways to lock door and frame on behalf of Assa Abloy, the goal is also for the concept to meet the requirements for safetyclass 5.The questions that will be answered in the report are what new innovative possibility to lock a door is there and does the concept fulfill security requirements for Scandinavian locks. First the report presents the theoretical background that contains the theories and tools that form the basis of the work. The work has been carried out with design-product development processes according to methods adapted to the project.The work includes an analysis of the market that together with requirements and target specificationsforms the basis for the concepts generated. The concepts have been generated through internal and joint brainstorming. A total of 48 concepts were generated and screened against three control questions. The remaining 17 concepts were screened in Pugh's matrix resulting in 4 remaining concepts. Physical models were developed for the four concepts and presented at a workshop. 3D printing was used for the conceptmodeling. With a concept selection workshop, a final concept was developed with the help of the participants opinions and ratings of the concept's properties, based on several selected questions.The project resulted in one concept including several components that were prototyped. The components were made with additive manufacturing and then implemented in an already existing lockcase. To demonstrate and visualize their function and to prove the concept itself works. Whether the concept can meet the security requirements for Scandinavian locks cannot be determined as this would require physical tests that would require a prototype made with the final manufacturing method in the final materials. This is also due to the approach of implementing the concept in a lock housing with a lower security class than the target. This is something that is interesting to investigate in future studies since testing is beyond the scope of the delimitations.
80

Off-line-programmering av en industriell robotcell för automatiserad additiv tillverkning : - En nybörjarvänlig dokumentation / Off-line-programming of an industrial robot cell for automated additive manufacturing : - A beginner-friendly documentation

Håkansson Burelius, Martin, Blomqvist, Dennis January 2021 (has links)
För att industrier ska hålla sig tekniskt uppdaterade krävs det att studenter, som så småningom blir personal, får utbildning som strävar efter modernisering. En viktig del inom modernisering i dag är automatisering via exempelvis automatiserad additiv tillverkning och off-line-programmering (OLP) som båda besitter stor potential, inte minst inom tillverkningsindustrin. Dessvärre så förekommer det brist på dokumentation om hur denna process går till steg för steg till färdig produkt, därför ämnar sig denna studie till att försöka täcka denna kunskapslucka genom att tillhandahålla en nybörjarvänlig dokumentation om processerna. Dokumentationen ska kunna bidra som referensverktyg i utbildningssyfte, där användaren kan genom nybörjarvänliga guider följa processen steg-för-steg från CAD-modell i SolidWorks till skapandet av robotbanor via 3D-printerprogrammet Slic3r och genom simuleringsprogrammen RoboDK och MotoSim utföra OLP som leder till simulering av additiv tillverkning. Tillvägagångssättet som tagits fram i denna studie valideras även genom automatiserad additiv tillverkning i verklig robotcell. Olika problem och idéer kring framtida forskning tas även upp i denna studie för att kunna utveckla och optimera processen. / In order for industries to stay technically up-to-date, it is necessary that students, who eventually become staff, receive education that strives for modernization. An important part of modernization today is automation via, for example, automated additive manufacturing and off-line programming (OLP), both of which have great potential, not least in the manufacturing industry. Unfortunately, there is a lack of documentation on how this process goes step by step to the finished product, so this study aims to try to cover this knowledge gap by providing a beginner-friendly documentation on the processes. The documentation should be able to contribute as a reference tool for educational purposes, where the user can through beginner-friendly guides follow the process step-by-step from CAD model in SolidWorks to the creation of robot paths via the 3D printer program Slic3r and through the simulation programs RoboDK and MotoSim perform OLP leading to simulation of additive manufacturing. The approach developed in this study is also validated through automated additive manufacturing in real robot cells. Various problems and ideas about future research are also addressed in this study in order to be able to develop and optimize the process.

Page generated in 0.0304 seconds