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Type of Document Dissertation Author Agarwal, Harish URN etd-12162004-132602 Title RELIABILITY BASED DESIGN OPTIMIZATION: FORMULATIONS AND METHODOLOGIES Degree Doctor of Philosophy Department Aerospace and Mechanical Engineering Advisory Committee
Advisor Name Title Alan P. Bowling Committee Member John E. Renaud Committee Member Stephen M. Batill Committee Member Steven B. Skaar Committee Member Keywords
- optimization
- uncertainty
- design
- reliability
Date of Defense 2004-12-08 Availability unrestricted Abstract Modern products ranging from simple components to complex systems should be designed to be optimal and reliable. The challenge of modern engineering is to ensure that manufacturing costs are reduced and design cycle times are minimized while achieving requirements for performance and reliability. If the market for the product is competitive, improved quality and reliability can generate very strong competitive advantages. Simulation based design plays animportant role in designing almost any kind of automotive, aerospace, and consumer products under these competitive conditions. Single discipline simulations used for analysis are being coupled together to create complex coupled simulation tools. This investigation focuses on the development of efficient and robust methodologies for reliability based design optimization in a simulation based design environment.
Original contributions of this research are the development of a novel efficient and robust unilevel methodology for reliability based design optimization, the development of an innovative decoupled reliability based design optimization methodology, the application of homotopy techniques in unilevel reliability based
design optimization methodology, and the development of a new framework for reliability based design optimization under epistemic
uncertainty.
The unilevel methodology for reliability based design optimization is shown to be mathematically equivalent to the traditional nested formulation. Numerical test problems show that the unilevel methodology can reduce computational cost by at least 50% as
compared to the nested approach. The decoupled reliability based design optimization methodology is an approximate technique to
obtain consistent reliable designs at lesser computational expense. Test problems show that the methodology is computationally efficient
compared to the nested approach. A framework for performing reliability based design optimization under epistemic uncertainty is also developed. A trust region managed sequential approximate
optimization methodology is employed for this purpose. Results from numerical test studies indicate that the methodology can be used for
performing design optimization under severe uncertainty.
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