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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

Applying Case-Based Reasoning to Assembly Part Design

Chang, Guanghsu, Su, Cheng Chung, Priest, John W. 01 December 2006 (has links)
Over 70% of final product costs are determined by initial product design. Hence, to depict a capable and reliable part design is important during the part conceptual design phase. Case-Based Reasoning (CBR), based on analogical reasoning, is a problem solving methodology. This paper proposes the CBR architecture applied to assembly part design for effectively managing previous design experience and evaluating assemblability and manufacturability of assembly part design. The results can provide a useful reference for novices to reuse and revise previous experience and experienced designers to impart their expertise through CBR methodology.
2

Underactuated Exoskeletons for Lifting, Carrying, and Walking Assistance

Folta, Nathan Allen 24 July 2023 (has links)
Exoskeletons are rapidly emerging from the realm of science-fiction myth to practical reality in everyday life. Various designs have provided viable means for individuals to regain capabilities that were lost or perform tasks not previously possible by their ability alone. In this research, I propose two novel exoskeletons for walking assistance and heavy load carriage. The first exoskeleton can be used to provide assistance for walking in various applications such as industrial productivity, rehabilitation, and military or space training. We introduce a design for a lower body wearable device that supports up to 80% of the user's body weight (667 N peak force) with a single actuator on each leg. Its underactuated design directs force through the user's center of mass with a single sprocket-chain driven prismatic actuator on each leg, allowing for natural gait and mobility. The device is optimized for simplicity, ease of assembly, low cost, and weight. The second design aims to counteract the one of the leading causes of injury in the workplace, repetitive and heavy lifting. The Heavy Lift and Carry Exoskeleton (HeavyLC Exo) is capable of safely lifting and carrying loads up to 36 kg (80 lbs) while minimizing the number of actuators to reduce weight and complexity. The HeavyLC Exo allows the user to direct the object, pause and hold the object steady mid-lift, and follow the natural kinematics of lifting. It is secured to the user with shoulder, chest, and dual thigh straps, along with an adjustable waist belt and overshoe attachment. Powered by two 14.8 V batteries and an off-board air compressor, the HeavyLC Exo has a total of 20 DOF, with 6 actuated DOF and 14 free DOF. The arms use only two actuators each, providing powered lifting and arm retraction/extension, and allowing a wide range of body postures; the legs are powered by single pneumatic actuators on each leg connected to the foot accompanied by a passive spring element to prevent excessive pelvic tilt and leg abduction during swing. The control system requires directional forces from the user at the tool handle of 19 N (4.3 lbf) on average. Current design limitations necessitate the user to provide up to 280 N (62.9 lbf) at the hip during worst load conditions, and future design optimization is proposed. A fully functional prototype of HeavyLC Exo is built, fully tested, and analyzed for improvement. / Master of Science / Exoskeletons, which were once only seen in science fiction, are now becoming a reality in everyday life. Various designs have made it possible for people to do things they couldn't do before or regain abilities they lost. In this research, two new exoskeletons are proposed - one for walking assistance and the other for carrying heavy loads. The first exoskeleton is designed to help people walk. It supports up to 80 % of the user's body weight with a single actuator on each leg, which directs force through the center of mass, allowing for natural gait and mobility. It's simple, easy to assemble, low-cost, and lightweight, making it useful in various applications such as medical rehabilitation, military or space training, and industrial productivity. The second exoskeleton is designed to help people lift and carry heavy objects, which is a common cause of workplace injuries. The Heavy Lift and Carry Exoskeleton (HeavyLC Exo) can safely lift and carry objects up to 36 kg (80 lbs) while minimizing the number of actuators to reduce weight and complexity. It's worn by the user using shoulder, chest, and dual thigh straps, along with an adjustable waist belt and overshoe attachment. The exoskeleton is powered by two batteries and an off-board air compressor, and has 20 degrees of freedom, with 6 powered and 14 non-powered, giving it significant flexibility to conform to lifting and walking motions allowing it to function with normal user range of motion. The arms use two actuators each to provide powered lifting and arm retraction/extension, while the legs are powered by single pneumatic actuators on each leg connected to the foot accompanied by a elastic spring element. The control system requires the user to lift and maneuver about 1.9 kg (4.2 lbs) to direct the object. A fully functional prototype has been built, tested, and analyzed for changes in the future.
3

Optimisation of ceiling attachment for AVPOS using FEA

Koskenranta, Mikael January 2015 (has links)
In product manufacture and assembly it is important to lower materials usage and assembly timewhile retaining a safety margin against structural failure. In this project the ceiling attachment of theAVPOS offloading arm is redesigned based on objectives identified by Löfs Specialmaskiner. Theoriginal ceiling attachment is analysed using finite element analysis to identify any structuralweaknesses to be addressed during redesign. Based on information gained during the FEA threeconcepts are generated and rated based on their estimated assembly times, material usage, partscount and the cutting length for machining.One concept is selected for further topology optimisation and iterative FEA, where material isremoved from the selected concept design while maintaining safety objectives. The optimised designdeveloped during this project is shown to have a lower number of parts, lower usage of material andassembly time while retaining an overall FOS value of 4.In addition to redesigning the ceiling attachment, alternative bearings are also investigated whichchanges the existing ball bearings to a self-aligning sliding bearing with self-lubricating properties,lowering the machining tolerances as well as lowering the needs for service.This project contributes to lowering material usage and ease of assembly in the product AVPOS thatis manufactured by Löfs Specialmaskiner. The redesigned ceiling attachment along with thesuggested bearings will likely simplify future manufacturing as well as lower any concerns for damageto people and property as a result of structural failure.
4

Designing for laser sintering

Gerber, G.F., Barnard, L.J. January 2008 (has links)
Published Article / Until recently solid freeform fabrication (SFF) technology has been used mostly for production of prototype parts. However, as this technology matures, the initiative of utilising it for the manufacture of end-use products is establishing itself. As this tendency to use SFF for actual production runs increases, a demand is developing for sets of process-specific design for manufacture (DFM) guidelines that will assist designers who are designing parts for manufacture by a specific rapid manufacturing (RM) process. The purpose of this paper is to provideRMdesigners with such a series of processspecific design for manufacture guidelines.
5

Redesign supported by data models with particular reference to reverse engineering

Borja Ramirez, Vicente January 1997 (has links)
The research reported in this thesis is focused on the creation of a CAE system to support Reverse Engineering. It is centred around the computational representation of products (Product Model) and manufacturing capabilities (Manufacturing Model). These models are essential for modem and future software systems aimed to assist the design process, enabling data sharing among the participants who use various computational tools. Reverse Engineering is employed as a particular context and motivation for exploring the application of the models. The research builds on the achievements of the recently finished Model Oriented Simultaneous Engineering System (MOSES) project, undertaken jointly by Leeds University and the Department of Manufacturing Engineering of Loughborough University. MOSES' work on information modelling was analysed and combined together with the original proposals of the author to elaborate a suitable support to Reverse Engineering, applicable to redesign in general. A process for Reverse Engineering is proposed and documented and a data model driven CAE system to support it is specified. The CAE system includes a Product Model, a Manufacturing Model and two software application environments. The Product Model of the system is based on the information requirements of the Reverse Engineering process and is suitable for representing multi-component products, from different perspectives through its life cycle. The applications assist the characteristic activities of Reverse Engineering. In particular, the system is used for exploring the application of Product and Manufacturing Models in supporting Design for Manufacture. The theoretical research is tested by the use of a case study which explores the Reverse Engineering of a component. This work is supported by a prototype software instance of the CAE system. The case study component is an axle which forms part of a product designed and manufactured by a collaborating company.
6

Arbetsmetodik för konstruktion av stålkonstruktioner med hänsyn till miljö och ekonomi

Erikanders, Jens, Olsson, Oskar January 2022 (has links)
Sammanfattning Det är allmänt känt att global uppvärmning är ett problem som grundar sig i att för mycket växthusgaser släpps ut. Detta måste förändras för att effekterna av global uppvärmning inte ska förstöra viktiga ekosystem. Av Sveriges industrier orsakar stålindustrin den största negativa miljöpåverkan, stålindustrin är därför ett av de främsta områdena att minska miljöpåverkan inom. För att minska miljöpåverkan krävs en metodik, som även sänker kostnaden på produkten.  Studien resulterade i en arbetsmetodik genom att använda beprövade metoder och jämföra mot en referenskonstruktion. Beprövade metoder som tillämpades för att minska miljöpåverkan, kostnaden samt uppnå kundkraven var: Topologioptimering, modulär konstruktion, Design for Manufacture and Assembly, och Lean Construction. Design for Environment diskuterades även.  Nulägesanalys utfördes för att skapa underlag till genomförandet av metoderna.  Metoderna tillämpades genom koncept som kartlades i ett miljö- och kostnadsdiagram tillsammans med referenskonstruktionen. Metoderna utvärderades genom tolkning av diagrammet och kundkravsmatris. Utvärderingen resulterade i en slutgiltig metodik som beprövades genom ett slutgiltigt koncept. Den slutgiltiga metodiken validerades med det slutgiltiga konceptet. Arbetet resulterade i en arbetsmetodik, följande arbetsmetodik är en förkortad verision: (1) Entydiga kundkrav; (2) flera koncept med målet att minska variationen och förenkla; (3) utvärdera konceptens möjligheter till modularisering; (4) det bästa konceptet väljs; (5) spänningsanalysera konceptet för att kunna justera överdimensionerade delar; (6) applicera DfMA råd, minska antalet delar som kräver lyftanordning vid montering. Arbetsmetodiken validerades genom att skapa ett slutgiltigt koncept. Konceptet uppfyller samma krav som referenskonstruktionen. Tidigare koncept har genomförts på en avgränsning av referenskonstruktionen, vilket medförde att delar av koncepten beaktades i den slutgiltiga arbetsmetodiken. Det kan ha medfört en viss felmarginal i valideringen. Om fler referenskonstruktioner var tillgängliga kunde valideringen gjorts annorlunda. / Summary Global warming is a commonly known problem based on the amount of greenhouse gas emissions; a change is therefore necessary for important ecosystems not to be disrupted. The steel industry sector accounts for the largest environmental impact of Swedish industry, which makes it one of the most important areas for improvements to be made [1]. To reduce the environmental impact, a method is required which also lowers the cost of the product. This study resulted in a methodology by using proven methods and comparing against a reference construction. The following methods that were used to satisfy the customer requirements and striving towards environmental and economic sustainability were: Topology optimization, modular construction, Design for Manufacture and Assembly, Lean Construction, Design for Environment was discussed. A situation analysis was preformed to create a basis for the implementation of the methods. Application of the methods was carried out by mapping the concepts in an environment-cost-diagram with the reference. The methods were evaluated by interpreting the diagram and Pughs matrix, the evaluation resulted in a methodology that was applied through a final concept. The work resulted in a methodology, which is presented in a shortend verision: (1) Clear customer requirements; (2) several concepts with the goal of reducing variation and simplifying; (3) evaluating the concept's possibilities for modularization; (4) over all best concepts is selected; (5) Stress Analysis on the selected concept to make adjustment on oversized parts; (6) apply DfMA advise, reduce the number of parts that require lifting equipment during assembly. The method was validated by creating a concept with the final methodology. The concept met the same requirements as the reference construction. Part of the reference construction has eariler been made concepts of, which led to ideas of the earlier made concepts were taken on to the final concept. This led to certain margin of error in the validation. If other reference constructions were available, validation could’ve be done differently.
7

Development of a lean design framework for enhancing the application of product design

Alam, Rahman January 2015 (has links)
Substantial benefits can be achieved through the adoption of lean type thinking earlier at the design stage to create more viable products. A complex design cannot be easily leaned out in production; therefore, the production of affordable and sustainable products requires effective lean design considerations at the conceptual level. The research presented in this thesis investigates and demonstrates the application of lean design for product enhancement. The aim of the research was to develop a novel lean design framework that would support the generation of product design with attributes such as maximise value, manufacturable, and operable with minimum waste and resources ensuring avoidable harm is eliminated. The framework consists of a systemised process which is organised in to phases and activities that provides a unique practical manner to lean out a design. The construction of the framework initiated with an extensive literature review and proceeded with an industrial field study which consisted of 34 interviews with 11 manufacturing companies in Europe. The findings were amalgamated to generate a lean design definition and principles which would form the foundations of the framework. A real-life industrial case study of an offshore oil/water separator was used to validate the framework. In conclusion, the lean design framework provides the necessary means by which a lean design can be achieved. As a result a functionally viable and enhanced design that is cheaper to manufacture through controlling waste and eliminating avoidable harm occurrence can be realised with minimal effort. The research makes the following contributions: (1) identification of essential elements in lean design, (2) generation of a lean design definition and principles, (3) Lean Design Framework development and (4) illustrative guidelines based on the framework to be used by designers in realising a lean product design.
8

An experimental cost model for composite parts using vacuum assisted resin transfer moulding (VARTM)

Vogt, Christian 03 1900 (has links)
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Vacuum assisted resin transfer moulding (VARTM) belongs to the category of resin infusion techniques that use lower than atmospheric pressure to infiltrate a reinforced cavity. This technique has various advantages; however, manufacturing costs can be relatively high due to more difficult shapes fabricated and a lack of knowledge regarding cost driving factors. The objective of this study was to develop a cost model for composite parts. Such a model allows the estimation of manufacturing costs of shapes of different geometries. Therefore, it provides a comparison to alternative manufacturing techniques, such as metal forming or composite spray lay-up and helps to avoid unnecessarily expensive design features. The proposal was made to split complex shaped composite parts into individual basic shapes, which are further investigated here. For the basic shapes, an experimental approach was used where the manufacturing times of each process step are measured and then statistically analysed. Infusion simulation software was used to obtain additional filling times to complete the design of experiments. This method allows the estimation of manufacturing times of composite parts with different geometries. The manufacturing times were validated to that of a complex shaped industrial part, with reasonable results. Finally, a flexible cost model was developed to compare different manufacturing techniques and to estimate the manufacturing costs. / AFRIKAANSE OPSOMMING: Vakuumgesteunde harsinspuitingsgietwerk (VARTM) behoort tot die kategorie harsinspuitingstegnieke wat laer-as-atmosferiese druk gebruik om ʼn versterkte holte binne te dring. Hierdie tegniek hou verskeie voordele in. Tog kan vervaardigingskoste betreklik hoog wees wanneer dit by ingewikkelder vorms en ʼn gebrek aan kennis met betrekking tot kostesnellers kom. Die doelwit van hierdie studie was om ʼn kostemodel vir saamgestelde onderdele te ontwikkel. Die model maak voorsiening vir die raming van die vervaardigingskoste vir verskillende afmetings. Sodoende bied dit ʼn vergelyking met alternatiewe tegnieke, en help voorkom onnodig duur ontwerpkenmerke. Daar is voorgestel dat dele met ingewikkelde vorms in individuele basiese vorms verdeel word, wat dan hier verder ondersoek word. Vir die basiese vorms word ʼn eksperimentele benadering gebruik waar die vervaardigingstye in elke prosesstap gemeet en statisties ontleed word. Voorts word inspuitingsimulasiesagteware gebruik om komplementêre inspuitingstye te bepaal ten einde die eksperimentele ontwerp te voltooi. Hierdie metode maak dit ook moontlik om die vervaardigingstye vir saamgestelde materiaal onderdele van verskillende afmetings te raam. Die vervaardigingstye word dan bevestig aan die hand van dié van ʼn kompleks gevormde industriële onderdeel, met redelike resultate. Uiteindelik word ʼn buigsame kostemodel ontwikkel om verskillende vervaardigingstegnieke te vergelyk en die vervaardigingskoste te raam.
9

Research on New Product Development Process

謝政儒, Cheng-Ju Hsieh Unknown Date (has links)
由於大環境的改變,公司間的競爭越來越激烈;顧客對新產品的需求也因為新技術的出現日益增加。為了因應全球化競爭及產品生命週期縮短的大環境,迅速及優異的新產品發展成為公司重要的競爭優勢。為了強化公司的競爭優勢,新產品發展已成為一重要議題。本論文著重於研究改善新產品發展的過程,探討影響新產品發展的關鍵因素,尤其是生產與研發間的關係。 本論文分為五個部分,第一章探討新產品發展的概念及基礎理論,說明新產品發展從單一功能政策進化為今日的跨功能性政策的一環。第二章對影響新產品發展的關鍵因素做詳盡介紹,說明跨功能性的整合將會是新產品發展成功的關鍵方法。第三章仔細討論研發與製造間的關係,並將兩者的角色由傳統的分別為單一部門功能的觀點打破,且將產品的設計與製程均視為新產品發展的重要功能,試圖詮釋將單一個人╱部門的知識與成功的新產品發展連結的可能性。第四章將探討知識傳遞的限制、知識管理及組織學習的基本理論。第五章將介紹重要的管理上、組織上及技術上的支援工具,並希望藉由這樣的分析能夠瞭解新產品開發過程中各關鍵因素間的關係。第六章將介紹實務上所使用的新產品開發觀念,這部分的資料是由個案訪問而來,選了三家不同產業具國際營運的公司為例,對實務做驗證。最後,提出一新產品開發的「最佳實務」,包括了重新定義新產品開發過程中的功能,並提出一良好管理新產品開發的建議。 / Nowadays the competitions among companies become more and more fierce due to the dramatic change of competitive environment. The demands of new products are accelerated by the emerging new technologies. The rapid and excellent new product development (NPD) has become a great strategic advantage to be accommodated to the global competition with shorter product life cycle. In order to enhance the competitive advantage, improving NPD has become a vital issue for companies. This thesis focuses on improving the NPD process. Factors influencing the NPD process are discussed in detail, especially the interface between R&D and production. The thesis is divided into five parts, starting with a general view on NPD in the first chapter. There it will be shown, how NPD has changed over the last decades from a traditional approach of functional-development to a cross-functional process today. Factors influencing this effective collaboration are presented in chapter two. In chapter three, the interface between R&D and production is directly scanned. It will be distinguished between the individual knowledge bases of the different departments. Process and product knowledge can be identified as the parts to be matched and will be illustrated. Consequently, the possibilities of linking those knowledge bases during NPD are shown. Chapter four will focus on the limitations of knowledge transfer and the fundamentals of knowledge management and organizational learning will be presented. In chapter five, supportive organizational, managerial and technological tools will be analyzed. The multiple views on NPD assure that all factors influencing the process are analyzed and proven according to their leverage on the process. In chapter six, currently used NPD concepts are outlined. The information presented was gathered through interviews carried out at globally operating companies who have technological centers and production sites in Sweden. To avoid focusing on NPD practices in an industry, the companies were chosen according to their product lines and customer segments. The final part will present best practices in NPD. This includes reconsidering all the discussed aspects and presenting a recommendation about how to organize NPD superiorly.
10

Produktionsoptimering av elektromagnetiska omrörare - "ORD 43P" och "EM Stabilizer"

Kabroo, Carl Gustaf, Willenius, Robert January 2013 (has links)
Examensarbetet inom produktutveckling – konstruktion utfördes under perioden februari till juni 2013 och omfattar 15 högskolepoäng (C-nivå), och är den slutliga kursen inom högskoleingenjörsprogrammet Innovation och produktdesign. Examensarbetet behandlade problematiken kring produktionsanpassning och kostnadsoptimering av två stycken elektromagnetiska omrörare vid företaget ABB, Process Automation, Metallurgy i Västerås. Efter kontakt med handledaren från ABB, Jan-Erik Eriksson, påbörjades projektarbetet med att tillverkningsanpassa konstruktionen av produkterna ORD 43P och EM Stabilizer. För att åstadkomma kostnadsoptimerad och produktionsanpassad konstruktion tillämpade författarna följande produktutvecklingsverktyg: Design for Cost, Design for Manufacture och Design for Assembly. För att kontrollera att konstruktionen blev optimal, men också att den inte brister under belastning använde examensarbetarna det datorbaserade hållfasthetsverktyget finita elementmetoden i CAD-programmet SolidWorks. Val av komponenter baserades på komponenternas pris per kilo. För att välja det optimala materialet, det vill säga högsta hållfasthet till lägsta pris använde författarna materialdatabasprogrammet CES EduPack. De utvalda materialen från programmet kunde inte författarna påfinna som standard på marknaden, varför författarna ändrade strategi till att jämföra och välja material utifrån marknadsundersökning av standardmaterial hos leverantörer.   ORD 43Ps komponenter optimerades konstruktionsmässigt gentemot befintliga komponenter och härvstag och isolerplattor kostnadsreducerades markant. Komponenten stomme grundutförande undersöktes översiktligt.  Genom att produktutveckla komponenterna härvstag, isolerplattor och stomme grundutförande minskade kostnaderna för ORD 43P med 2,47 %.  Författarna ansåg att ORD 43Ps totala kostnader kan minska mellan 10-25 % eftersom många av dess komponenter är överdimensionerade och består av dyrare material än vad som krävs.  EM Stabilizer’s komponenter, lock och tryckluftsslang, utformades med optimal konstruktion och kostnadsreducerades.  Genom att produktutveckla komponenterna lock och tryckluftsslang minskade kostnaderna för EM Stabilizer med 1,3 %.  Författarna förmodar att EM Stabilizer’s kostnader kan minska, eftersom den är relativt ny på marknaden. ABB vill säkerställa att produkten uppnår sin garanterade livslängd genom att överdimensionera många av produktens komponenter och använda dyrare material än vad som är nödvändigt. / The thesis in product development – design was carried out between February and June 2013 and includes 15 credits (C-level), and is the final course of the Bachelor Program in Engineering, Innovation and Product Design.  The thesis dealt with the problem of adaptation to production and cost optimization of two pieces of electromagnetic stirrers at the company ABB, Process Automation, Metallurgy in Västerås. After contact with the supervisor from ABB, Jan-Erik Eriksson, the project work commenced to adapt the manufacturing design of the product ORD 43P and EM Stabilizer. To achieve cost-optimized production and production adapted design, the authors applied the following product development tools: Design for Cost, Design for Manufacture and Design for Assembly. To verify that the design was optimal, but also that it did not break during stress, the authors used the computer based module finite element method of the CAD program SolidWorks.  The selection of components was based on the component’s price per kilo.  To select the optimum material, that is high strength and affordable, the authors used the material database software CES EduPack. The materials selected from CES EduPack could not be found by the authors as standard material at the market. Therefore, the authors changed strategy to compare and select materials based on market research of standard materials with suppliers. The components of ORD 43P were optimized in terms of design in comparison with existing components coil bracket and insulation boards. They were also cost reduced significantly. The component frame base was examined briefly.  Through product development the components coil bracket, insulating boards and frame base the total cost of ORD 43P was reduced by 2,47 %.  The authors found that the total cost of ORD 43P could be reduced between 10-25 % as many of its components are oversized and made ​​of more expensive materials than needed.  The components of EM Stabilizer, cover and pneumatic hose, were designed with optimum design and was cost reduced.Through product development the components cover and pneumatic hose the costs of EM stabilizer were reduced by 1,3 %.  The authors assume that the costs of the EM Stabilizer can be reduced, because it is relatively new at the market. ABB want to ensure that the product reach its guaranteed life by over-sizing many of the components of the product and use more expensive material than necessary. / Kostnadssänkningsprojekt

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