No description available.

This thesis discusses a methodology for probabilistic design optimization of aircraft structures subject to a multidisciplinary set of requirements originating from the desire to minimize structural weight while fulfilling the demands for quality, safety, producibility, and affordability. With this design methodology as the framework, a software is developed, which is capable of performing design optimization of metallic built-up beam structures where the material properties, external load, as well as the structural dimensions are treated as probabilistic random variables. The structural and failure analyses are based on analytical and semi-empirical methods whereas the component reliability analysis is based on advanced first-order second moment method. Metrics-based analytical models are used for the manufacturability analysis of individual parts with the total manufacturing cost estimated using models derived from the manufacturing cost / design guide developed by the Battelle¡¯s Columbus Laboratories. The resulting optimization problem is solved using the method of sequential quadratic programming. A wing spar design optimization problem is used as a demonstrative example including a comparison between non-buckling and buckling web design concepts. A sensitivity analysis is performed and the optimization results are used to highlight the tradeoffs among weight, reliability, and manufacturing cost.

Inledning: Marknadstillväxten har gått framåt senaste åren och företag bör hitta konkurrensfördelar för att fortsätta vara lönsamma. Priser bör anpassas efter marknaden och vetskap om tillverkningskostnad blir viktigt för tillverkande företag. För att beräkna tillverkningskostnad för produkter kan självkostnadskalkylering och totalkostnadsmodellen användas. Ett materialflöde i en produktion består av processer som innefattar hantering, förflyttning och lagring av material. Studien har inte funnit någon tidigare forskning eller modell som förklarar relationen mellan materialflöden och tillverkningskostnad på en detaljerad nivå vilket motiverar studien. Syfte: Syftet med arbetet var att utforma och utvärdera en modell för bestämning av tillverkningskostnad med utgångspunkt från materialflöden i produktion med avseende på lagring, transport och tillverkningsoperationer. Metoder: En abduktiv ansats har använts för att besvara syftet och frågeställningar där teori och empiri har inhämtats parallellt under arbetets gång. I studien har teori och empiri lagt grund för kostnadsfaktorer som påverkar tillverkningskostnaden. Utformning av modell för bestämning av tillverkningskostnad: I studien har teoretiska och empiriska undersökningar utförts för att redogöra för olika kostnadsfaktorer som påverkar tillverkningskostnaden. Modellen använder tre aktiviteter för att kategorisera identifierade kostnadsfaktorer i ett materialflöde: operation, lagring och transport. Tillämpning och utvärdering av modell: Modellen tillämpades på fallföretaget Alderholmens mekaniska. Efter tillämpningen utvärderades modellen där styrkor och utvecklingsmöjligheter presenterades. Slutsats: Studiens bidrag är en modell för beräkning av tillverkningskostnad med utgångspunkt från materialflödet i produktionen. Modellen presenterar vilka faktorer som påverkar tillverkningskostnaden. Kapitlet avslutas med rekommendationer till framtida studier för att utöka kunskapen inom ämnet.

Composite structures can lower the weight of an airliner significantly. Due to the higher process complexity and the high material cost, however, the low weight often comes with a significant increase in production cost. The application of cost-effective design strategies is one mean to meet this challenge. In this thesis, a simplified form of direct operating cost is suggested as a comparative value that in combination with multidisciplinary optimization enables the evaluation of a design solution in terms of cost and weight. The proposed cost optimization framework takes into account the manufacturing cost, the non-destructive testing cost and the lifetime fuel consumption based on the weight of the aircraft, thus using a simplified version of the direct operating cost as the objective function. The manufacturing cost can be estimated by means of different techniques. For the proposed optimization framework, feature-based parametric cost models prove to be most suitable. Paper A contains a parametric study in which a skin/stringer panel is optimized for a series of cost/weight ratios (weight penalties) and material configurations. The weight penalty (defined as the specific lifetime fuel burn) is dependent on the fuel consumption of the aircraft, the fuel price and the viewpoint of the optimizer. It is concluded that the ideal choice of the design solution is neither low-cost nor low-weight but rather a combination thereof. Paper B proposes the inclusion of non-destructive testing cost in the design process of composite components, and the adjustment of the design strength of each laminate according to inspection parameters. Hence, the scan pitch of the ultrasonic testing is regarded as a variable, representing an index for the guaranteed material quality. It is shown that the cost for non-destructive testing can be lowered if the quality level of the laminate is assigned and adjusted in an early design stage. In Paper C and Paper D the parameters of the manufacturing processes are upgraded during the cost optimization of the component. In Paper C, the framework is extended by the cost-efficient adaptation of parameters in order to reflect the situation when machining an aluminum component. For different weight penalties, the spar thickness and stringer geometry of the provided case study vary. In addition, another cutter is chosen with regard to the modified shape of the stringer. In Paper D, the methodology is extended to the draping of composite fabrics, thus optimizing not only the stacking layup, but also the draping strategy itself. As in the previous cases, the design alters for different settings of the weight penalty. In particular, one can see a distinct change in fiber layup between the minimum weight and the minimum cost solution. Paper E summarizes the work proposed in Papers A-D and provides a case study on a C-spar component. Five material systems are used for this case study and compared in terms of cost and weight. The case study shows the impact of the weight penalty, the material cost and the labor rate on the choice of the material system. For low weight penalties, for example, the aluminum spar is the most cost-effective solution. For high weight penalties, the RTM system is favorable. The paper also discusses shortcomings with the presented methodology and thereby opens up for future method developments. / QC 20100723 / European Framework Program 6, project ALCAS, AIP4-CT-2003-516092 / Nationella flygtekniska forskningsprogrammet (NFFP) 4, project kostnadseffektiv kompositstruktur (KEKS)

Orientador: Maria Angela de Almeida Meireles / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-09T21:18:11Z (GMT). No. of bitstreams: 1 Leal_PatriciaFranco_D.pdf: 2381293 bytes, checksum: 5131ad6a5dbd2eb071d1516e4f5d09fc (MD5) Previous issue date: 2008 / Resumo: Este estudo teve por objetivo comparar o custo de manufatura (COM) de extratos vegetais e óleos voláteis de plantas aromáticas, condimentares e medicinais nativas ou adaptáveis ao cultivo brasileiro obtidos por processos de extração considerados limpos e que não agridem o meio ambiente. Foi realizado o estudo técnico-econômico do processo de extração com fluido supercrítico (SFE) e destilação por arraste a vapor (SD) para obtenção de extratos vegetais e óleos voláteis. A metodologia de estimativa de custo de manufatura utilizada neste estudo resulta em COM classe 4 ou 5, sendo uma estimativa preliminar para a decisão de prosseguimento ou a interrupção do projeto. As estimativas dos custos de manufatura dos extratos foram realizadas através das curvas globais de extração (OEC) dos sistemas determinadas experimentalmente neste trabalho (alecrim + vapor, camomila + vapor, erva-doce + vapor, erva-baleeira + vapor, erva-baleeira + CO2, canelinha + CO2) e também através das OECs da literatura (alecrim + vapor, alecrim + CO2, erva-doce + vapor, erva-doce + CO2,, gengibre + CO2, camomila + CO2, pimenta-do-reino + vapor, pimenta-do-reino + CO2, funcho + CO2,). As curvas globais de extração foram ajustadas a um spline contendo duas ou 3 retas: a primeira reta descreve a taxa de transferência de massa no período de taxa de extração constante (CER), a segunda reta descreve a taxa de transferência de massa no período de taxa de extração decrescente (FER) e a terceira reta descreve a taxa de transferência de massa no período controlado pela difusão (DC). Para o scale-up assumiu-se que o rendimento de extração e o tempo do processo para o equipamento em escala industrial são linearmente correlacionados aos parâmetros da escala laboratorial quando é mantida constante a razão entre a massa de solvente e a massa de alimentação. Os COMs para os extratos obtidos por SD e SFE foram estimados durante todo o processo de extração para tempos pré-selecionados ao longo das OECs. Para os extratos obtidos por SFE, o COM também foi estimado para dois tempos de processo préselecionados: (i) o tempo de ciclo correspondente ao período CER e denotado por tCER e (ii) tempo de ciclo correspondente à intercepção das retas que representam os períodos CER e DC e denotado por tCER2. O parâmetro tCER é amplamente proposto pela literatura e como uma boa aproximação para o tempo de ciclo do processo SFE, tendo em vista que aproximadamente 70% do leito de extração é esgotado nesta etapa. Para as OECs ajustadas a um spline linear contendo três retas o tempo de ciclo foi selecionado como tCER2. Através do estudo de simulação da etapa de separação extrato/solvente realizado para os sistemas funcho + CO2 e canelinha + CO2 foi possível observar que a condição de operação desta etapa tem grande influência na composição do extrato final. A pressão de operação do tanque flash igual a 40 bar foi considerada uma boa alternativa, pois tanto a perda de CO2 na corrente de saída de extrato quanto a perda de extrato na corrente de saída de solvente foram mínimas. O estudo da etapa de separação é uma área promissora e ainda pouco explorada frente à etapa de extração. Foi avaliado o impacto do custo fixo de investimento, custo de matéria-prima, custo de utilidades, custo de mão-de-obra e custo de tratamento de resíduos sobre o COM. Este estudo foi importante, pois quebrou o paradigma de que o custo fixo de investimento seria o fator de maior impacto no COM dos extratos produzidos por SFE. O custo de matéria-prima predominou na composição do COM dos extratos da grande maioria das matrizes vegetais obtidas por SFE e SD. A SFE é um processo promissor e já existem inúmeras unidades industriais operando na China, França, Alemanha, etc. A estimativa preliminar dos custos de manufatura dos extratos de erva-baleeira, alecrim, camomila, erva-doce e pimenta-do-reino obtidos por SFE e SD foram: US$ 914,00/kg e US$ 10.350,00/kg, US$ 214,00/kg e US$ 369,00/kg, US$ 277,00/kg e US$ 2.798,00/kg, US$ 216,00/kg e US$ 272,00/kg, US$ 198,00/kg e US$ 232,00/kg, respectivamente. Estes custos foram comparados ao preço de venda de similares produzidos no Brasil e/ou exterior. A produtividade anual para cada processo foi confrontada / Abstract: This study had the objective to compare the cost of manufacturing (COM) of vegetable extracts and volatile oils of aromatic, condimental and medicinal plants, natives or adaptable to cultivation in Brazil, obtained by extraction processes that are clean and harmless to the environment. A technical-economical study on supercritical fluid extraction (SFE) and steam distillation (SD) for obtaining of vegetable extracts and volatile oils was done. The methodology to estimate the cost of manufacturing used on this study produces estimation classified as COM class 4 or 5, being a preliminary estimation used in the decision of go or not go of the project. The cost of manufacturing estimations were done using information from the overall extraction curves (OEC) experimentally determined in this study (rosemary + steam, chamomile + steam, anise + steam, C. verbenacea + steam, C. verbenacea + CO2, C. zehntneri + CO2) and information obtained from literature for OECs (rosemary + steam, rosemary + CO2, anise + steam, anise + CO2, ginger + CO2, chamomile + CO2, black pepper + steam, black pepper + CO2, fennel + CO2). The overall extraction curves were fitted to a spline containing two or three lines: the first line describes the mass transfer rate for the constant extraction rate period (CER), the second line describes the falling extraction rate period (FER), and the third line describes the diffusion controlled rate period (DC). The scale-up procedure assumed that both the global yield and the time of processing of the industrial scale are linearly correlated to laboratory scale ones as long as the ratio of the solvent mass to the raw material mass is kept constant. The COMs of the extracts obtained by SD and SFE were estimated from beginning to end of the process at specified time intervals along the OECs. For the SFE process the COM was also estimated for two preselected times of process: (i) a time of cycle corresponding to CER period and denoted as tCER, and (ii) a time of cycle corresponding to the intercept of the CER and DC lines denoted in this study as tCER2. The tCER parameter is widespread in literature as being a good estimative for the time of processing for the SFE since approximately 70% of extraction bed is exhausted along this period. For the OECs adjusted to a linear spline containing three lines the time of cycle was chosen as tCER2. The simulation of the separation extract/solvent done for fennel + CO2 and C. zehntneri + CO2 system, showed that the operation conditions of this stage have great influence on the final composition of the extract. The operation pressure of 40 bar in the flash tank was considered as a good choice, since a minimum loss of CO2 (in the extract exit stream) and the extract loss (in the CO2 exit stream) were estimated. The study of the separation stage is a promising area, and still little explored when compared to the extraction stage. The impact of the fixed cost of investment, raw material cost, utilities cost, operational-labor cost and waste treatment cost on the COM were evaluated. This study was important since it broke the paradigm that the fixed cost of investment would be the factor of major impact on the COM of the extracts produced by SFE. The raw material cost was predominant on the composition of the COM of the extracts from most vegetable matrices obtained by SFE and SD. SFE is a promising process, and there already are many industrial units operating in China, France, Germany, etc. The preliminary estimative of the manufacturing costs of the extracts of C. verbenacea, rosemary, chamomile, anise and black pepper obtained by SFE and SD were: US$ 914.00/kg and US$ 10,350.00/kg, US$ 214.00/kg and US$ 369.00/kg, US$ 277.00/kg and US$ 2,798.00/kg, US$ 216.00/kg and US$ 272.00/kg, US$ 198.00/kg and US$ 232.00/kg, respectively. These costs were compared to the selling prices of similar products produced in Brazil and/or abroad. The annual productivities of each process were confronted. / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos

Varje gång en ny byggnad inreds eller renoveras behöver stora, tunga och otympliga föremål som skåp, diskhoar, handfat, fläktar med mera installeras i kök och badrum. Det finns olika system för att montera dessa men det kan ofta vara en komplicerad process. 2Xarm är ett verktyg som gör kök- och badrumsinstallationer säkert och smidigt. Skåp, hyllor och annat lyfts med verktyget för att sedan justeras och hållas på plats där de ska monteras. I nuläget är verktyget för dyrt att tillverka för att kunna säljas med tillräckligt god marginal. Därför var syftet med detta arbete att minska verktygets tillverkningskostnad utan att förändra dess patenterade design och funktion. Arbetet har utförts med hjälp av datorstödd modellering och via informationssökning. En fysisk prototyp lånades och modellerades av. Sedan har tillverkningsmetoder och materialval undersökts varpå tre alternativa konstruktionslösningar togs fram. Dessa anses dock inte ha minskat tillverknigskostnaden nämnvärt. Den huvudsakliga slutsatsen är att verktygets tillverkningskostnad inte gick att minska nämnvärt utan att förändra dess funktionalitet och patenterad design. Alternativt hade även en större produktionsvolym varit en effektiv metod att minska enhetskostnaden. / The 2Xarm tool simplifies kitchen and bathroom installations by securely lifting and installing heavy objects like cabinets and sinks. However, its current manufacturing cost is too high to sell the tool at sufficient profit margains. This report aimed to identify cost-saving measures while preserving the tool’s patented design and functionality. Using computer-aided modeling and research, we analyzed a physical prototype, explored different manufacturing methods, and evaluated material choices. These efforts resulted in three alternative design solutions that aimed to simplify the manufacturing and assembly process. However, these changes ultimately did not significantly reduce the manufacturing cost. In conclusion, achieving substantial cost reduction for the tool without compromising its design and functionality proved difficult. Alternatively, increasing production volume could be an effective approach to lower the unit cost.

This project attempts to research the manufacturing cost, with an emphasis on machining, of high performance flanges for Turbine Rear Structure (TRS) applications, as well as the tradeoffs with structural performance and weight. A combination of traditional cost modelling techniques from the literature, as well as, the non-conventional manufacturing complexity index, as cost indicator are implemented. A multidisciplinary study is carried out with the aid of ANSYS Workbench in the form of computer simulated experiments to investigate tradeoffs in flanges. It is concluded that multidisciplinary studies of cost, performance and weight lacked model robustness to draw sound conclusions about flange design. However, the manufacturing complexity index after partial validation with experienced engineers shows promising results, and could be a way forward to estimate final machining operation cost for flanges in the future. / Syftet för detta projekt är att undersöka tillverkningskostnaden, med tonvikt på bearbetning av högpresterande flänsar för turbinapplikationer (TRS), samt dess relation till strukturella prestanda och vikt. Traditionella kostnadsmodelleringstekniker kombineras med det ickekonventionella tillverkningskomplexitetsindexet och används som kostnadsindikator. En tvärvetenskaplig studie genomförs med hjälp av ANSYS Workbench i form av dator simulerade experiment för att undersöka flänsavvägningar. En slutsats av studien är att multidisciplinära modeller av kostnad, prestanda och vikt saknade robusthet för att kunna dra djupgående slutsatser om prestandan för en flänsdesign. Tillverkningskomplexitetsindexet visar dock, efter partiell validering med erfarna ingenjörer, lovande resultat och kan vara framgångsrikt ett sätt att uppskatta den slutliga bearbetningskostnaden för flänsar.

Fuel cells are an excellent opportunity to address the challenges of the energy supply of the future. The polymer electrolyte membrane fuel cell (PEMFC) stack consists of several core components such as the bipolar plates (BPP) and membrane electrode assembly (MEA). BPPs have an influence on stack dimensions, performance and lifetime as well as costs. The challenge is to design an optimal BPP for specific applications, considering the manufacturing effort and costs. Basically, two material concepts are currently available: polymer composite materials or metals. Compared to metallic BPPs, polymer-based BPPs show a longer service life and allow a high geometrical flexibility. Metallic BPPs possess a very thin overall thickness which makes them preferable for use in commercial automotive sector. Depending on the base material, different manufacturing processes are required. This article presents a comparison and an assessment of BPPs regarding possible manufacturing processes as well as resulting costs.