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The Global ETD Search service is a free service for researchers
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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.
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Managing Complexity and Uncertainty by a Modelling Approach for Decision Making in Integrated Product/Process Design / Maitrise de la complexité et incertitude pour l'aide à la décision en conception intégrée produit processus par des approches de modélisationsBabaeizadeh malmiry, Roozbeh 10 October 2016 (has links)
L'objectif principal lors de la conception et du développement de produits est d'augmenter la valeur de ceux-ci. La Valeur comprend deux aspects : la qualité et le coût. Afin de prendre en compte ces deux aspects, cette thèse se focalise sur la conception intégrée des produits et des processus, et en particulier sur la complexité du processus de conception et les incertitudes associées. Cette thèse propose une approche de modélisation systématique pour maitriser les incertitudes et gérer la complexité. Cette approche comprend deux phases: détermination du modèle et analyse du système. La première phase contient deux propositions : une approche de modélisation de produits basée sur la modélisation des flux d'énergie dans le cadre méthodologique Characteristics-Properties Modelling (CPM). Cette approche donne un cadre qui permet de facilité la transition d’une vue fonctionnelle à une vue structurelle associée à une modélisation quantitative. La seconde proposition porte sur l’aide du concepteur lors de la conception concurrente (IPPD) où à la fois les performances et les coûts sont pris en compte. Cette approche est basée sur le flux du processus en respectant le même cadre (CPM), elle donne aussi un cadre pour la transition fonctionnelle / structurelle. Les modélisations structurelles quantitatives permettent l’analyse de sensibilité, l’analyse des tolérances et l'optimisation. L’application de l'approche est démontrée par une étude de cas industriel.Grâce à cette approche, les caractéristiques modifiables et pertinentes du produit peuvent être déterminées. Le tolérancement peut être intégré dans le processus de conception et son impact sur la performance du produit peut être analysé. Les relations quantitatives du produit, du processus sont identifiées. Les incertitudes dans les relations et dans toutes les étapes de la modélisation peuvent être élicitées et maitrisées. Cette approche systématique donne un cadre pour le concepteur à travers le processus de conception pour prendre des décisions dans tous les niveaux de décomposition sur la base de la fonction requise et le coût de fabrication. L'approche est applicable tant pour la modélisation d'un produit existant (une approche d'optimisation), tant pour la modélisation d'un nouveau produit (phase de conception conceptuelle). / The main objective in product design and development is to increase the value of a product. Value includes two aspects of quality and cost. In order to take into account both aspects, this thesis aims at Integrated Product and Process Design, especially on product design complexity and its inherent (associated) complexities. This thesis proposes a systematic modelling approach to reduce uncertainty and manage complexity. The approach includes two phases: model determination and system analysis. The first phase contains two propositions: first, a product modelling approach based on energy flow modelling in the framework of Characteristics-Properties Modelling (CPM). This approach gives a modelling framework for a smoother transition from functional to structural views, with a quantitative modelling. The second proposition is to help the designer for decision making in concurrent designing (IPPD) where both performance and cost are taken into account. This approach is based on the process flows in the same framework (CPM). The second phase is to use the determined model of phase 1 to analyse the system. So, phase 2 includes sensitivity analysis, tolerance analysis and optimisation. An application of the approach is demonstrated through an industrial case study.Thanks to this approach, effective modifiable characteristics of the product on its performance are determined. Tolerancing can be integrated in design process and its impact on the product performance can be analysed. Quantitative links in product, in process and between product elements and process elements are identified. Uncertainty in the links and every step of modelling can be elicited and managed. This systematic approach gives a pathway to the designer through the design process to make decisions in every level of decomposition based on the required function and cost of manufacturing. The approach is applicable for both modelling an existing product (optimisation approach) and modelling a new product (conceptual design phase).
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Development of hybrid lifecycle cost estimating tool (hlcet) for manufacturing influenced design tradeoffSirirojvisuth, Apinut 21 May 2012 (has links)
In complex aerospace system design, making effective decision requires knowledge from all disciplines, both product and process perspectives. Manufacturing knowledge integration is most valuable during the early phase of the design since designers have more freedom, and design changes are relatively inexpensive. Yet, there is still lack of structured methodology that will allow feedback from the process perspective to show the impact of the design decisions in a quantifiable manner. The major metrics in the design decision as far as process is concerned are cost, time, and manufacturability. To incorporate these considerations in the decision making process without sacrificing agility and flexibility required during conceptual and preliminary design phases, a new set of software analysis tools are proposed. To demonstrate the applicability of this concept, a Hybrid Lifecycle Cost Estimating Tool (HLCET) is developed, and integrated to existing design methodology, Integrated Product and Process Development (IPPD). The ModelCenter suite is used to develop software architecture that seamlessly integrate between product and process analysis tools, and enable knowledge transfer between design phases. HLCET integrates high fidelity estimating techniques like process-based and activity-based into a hierarchical lifecycle cost model to increase the sensitivities of the top-down LCC model to changes or alternatives evaluated at the part or component level where tradeoff is required. Instead of applying arbitrary complexity factor to existing CERs to account for difference material or process selection, high fidelity tool can be used to related product and process parameters specific to the design to generate new result that can then be used to update top-level cost result. This new approach to lifecycle cost estimation allows for a tailored study of individual processes typically required for new and innovative designs. An example of a hypothetical aircraft wing redesign demonstrates the utility of HLCET.
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An integrated product – process development (IPPD) based approach for rotorcraft drive system sizing, synthesis and design optimizationAshok, Sylvester Vikram 20 September 2013 (has links)
Engineering design may be viewed as a decision making process that supports design tradeoffs. The designer makes decisions based on information available and engineering judgment. The designer determines the direction in which the design must proceed, the procedures that need to be adopted, and develops a strategy to perform successive decisions. The design is only as good as the decisions made, which is in turn dependent on the information available. Information is time and process dependent. This thesis work focuses on developing a coherent bottom-up framework and methodology to improve information transfer and decision making while designing complex systems. The rotorcraft drive system is used as a test system for this methodology.
The traditional serial design approach required the information from one discipline and/or process in order to proceed with the subsequent design phase. The Systems Engineering (SE) implementation of Concurrent Engineering (CE) and Integrated Product and Process Development (IPPD) processes tries to alleviate this problem by allowing design processes to be performed in parallel and collaboratively.
The biggest challenge in implementing Concurrent Engineering is the availability of information when dealing with complex systems such as aerospace systems. The information is often incomplete, with large amounts of uncertainties around the requirements, constraints and system objectives. As complexity increases, the design process starts trending back towards a serial design approach. The gap in information can be overcome by either “softening” the requirements to be adaptable to variation in information or to delay the decision. Delayed decisions lead to expensive modifications and longer product design lifecycle. Digitization of IPPD tools for complex system enables the system to be more adaptable to changing requirements. Design can proceed with “soft” information and decisions adapted as information becomes available even at early stages.
The advent of modern day computing has made digitization and automation possible and feasible in engineering. Automation has demonstrated superior capability in design cycle efficiency [1]. When a digitized framework is enhanced through automation, design can be made adaptable without the requirement for human interaction. This can increase productivity, and reduce design time and associated cost. An important aspect in making digitization feasible is having the availability of parameterized Computer Aided Design (CAD) geometry [2]. The CAD geometry gives the design a physical form that can interact with other disciplines and geometries. Central common CAD database allows other disciplines to access information and extract requirements; this feature is of immense importance while performing systems syntheses. Through database management using a Product Lifecycle Management (PLM) system, Integrated Product Teams (IPTs) can exchange information between disciplines and develop new designs more efficiently by collaborating more and from far [3].
This thesis focuses on the challenges associated with automation and digitization of design. Making more information available earlier goes jointly with making the design adaptable to new information. Using digitized sizing, synthesis, cost analysis and integration, the drive system design is brought in to early design. With modularity as the objective, information transfer is made streamlined through the use of a software integration suite. Using parametric CAD tools, a novel ‘Fully-Relational Design’ framework is developed where geometry and design are adaptable to related geometry and requirement changes. During conceptual and preliminary design stages, the airframe goes through many stages of modifications and refinement; these changes affect the sub-system requirements and its design optimum. A fully-relational design framework takes this into account to create interfaces between disciplines. A novel aspect of the fully-relational design methodology is to include geometry, spacing and volume requirements in the system design process.
Enabling fully-relational design has certain challenges, requiring suitable optimization and analysis automation. Also it is important to ensure that the process does not get overly complicated. So the method is required to possess the capability to intelligently propagate change.
There is a need for suitable optimization techniques to approach gear train type design problems, where the design variables are discrete in nature and the values a variables can assume is a result of cascading effects of other variables. A heuristic optimization method is developed to analyze this multimodal problem. Experiments are setup to study constraint dependencies, constraint-handling penalty methods, algorithm tuning factors and innovative techniques to improve the performance of the algorithm.
Inclusion of higher fidelity analysis in early design is an important element of this research. Higher fidelity analyses such as nonlinear contact Finite Element Analysis (FEA) are useful in defining true implied stresses and developing rating modification factors. The use of Topology Optimization (TO) using Finite Element Methods (FEM) is proposed here to study excess material removal in the gear web region.
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An IPPD approach providing a modular framework to closing the capability gap and preparing a 21st century workforceZender, Fabian 22 May 2014 (has links)
The United States are facing a critical workforce challenge, even though current unemployment is around 6.7%, employers find it difficult to find applicants that can satisfy all job requirements. This problem is especially pronounced in the manufacturing sector where a critical skills gap has developed, a problem that is exasperated by workforce demographics. A large number of employees across the various manufacturing sub-disciplines are eligible to retire now or in the near future. This gray tsunami requires swift action as well as long lasting change resulting in a workforce pipeline that can provide Science, Technology, Engineering, and Mathematics (STEM) majors in sufficient quantity and quality to satisfy not only the needs of STEM industries, but also of those companies outside of the STEM sector that hire STEM graduates. The research shown here will identify overt symptoms describing the capability gap, will identify specific skills describing the gap, educational causes why the gaps has not yet been addressed or is difficult to address, and lastly educational remedies that can contribute to closing the capability gap. A significant body of literature focusing on engineering in higher education has been evaluated and findings will be presented here. A multidisciplinary, collaborative capstone program will be described which implements some of the findings from this study in an active learning environment for students working on distributed teams across the US. Preliminary findings regarding the impact of these measures on the quantity of engineers to the US economy will be evaluated.
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A plm implementation for aerospace systems engineering-conceptual rotorcraft designHart, Peter Bartholomew 08 April 2009 (has links)
The thesis will discuss the Systems Engineering phase of an original Conceptual Design Engineering Methodology for Aerospace Engineering-Vehicle Synthesis. This iterative phase is shown to benefit from digitization of Integrated Product&Process Design (IPPD) activities, through the application of Product Lifecycle Management (PLM) technologies. Requirements analysis through the use of Quality Function Deployment (QFD) and 7 MaP tools is explored as an illustration. A "Requirements Data Manager" (RDM) is used to show the ability to reduce the time and cost to design for both new and legacy/derivative designs. Here the COTS tool Teamcenter Systems Engineering (TCSE) is used as the RDM. The utility of the new methodology is explored through consideration of a legacy RFP based vehicle design proposal and associated aerospace engineering. The 2001 American Helicopter Society (AHS) 18th Student Design Competition RFP is considered as a starting point for the Systems Engineering phase. A Conceptual Design Engineering activity was conducted in 2000/2001 by Graduate students (including the author) in Rotorcraft Engineering at the Daniel Guggenheim School of Aerospace Engineering at the Georgia Institute of Technology, Atlanta GA. This resulted in the "Kingfisher" vehicle design, an advanced search and rescue rotorcraft capable of performing the "Perfect Storm" mission, from the movie of the same name. The associated requirements, architectures, and work breakdown structure data sets for the Kingfisher are used to relate the capabilities of the proposed Integrated Digital Environment (IDE). The IDE is discussed as a repository for legacy knowledge capture, management, and design template creation. A primary thesis theme is to promote the automation of the up-front conceptual definition of complex systems, specifically aerospace vehicles, while anticipating downstream preliminary and full spectrum lifecycle design activities. The thesis forms a basis for additional discussions of PLM tool integration across the engineering, manufacturing, MRO and EOL lifecycle phases to support business management processes.
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