Dissertations / Theses on the topic 'Reliability Design Optimization methods (RBDO)'
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Cho, Hyunkyoo. "Efficient variable screening method and confidence-based method for reliability-based design optimization." Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/4594.
Mansour, Rami. "Reliability Assessment and Probabilistic Optimization in Structural Design." Doctoral thesis, KTH, Hållfasthetslära (Avd.), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-183572.
QC 20160317
Ndashimye, Maurice. "Accounting for proof test data in Reliability Based Design Optimization." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97108.
ENGLISH ABSTRACT: Recent studies have shown that considering proof test data in a Reliability Based Design Optimization (RBDO) environment can result in design improvement. Proof testing involves the physical testing of each and every component before it enters into service. Considering the proof test data as part of the RBDO process allows for improvement of the original design, such as weight savings, while preserving high reliability levels. Composite Over-Wrapped Pressure Vessels (COPV) is used as an example application of achieving weight savings while maintaining high reliability levels. COPVs are light structures used to store pressurized fluids in space shuttles, the international space station and other applications where they are maintained at high pressure for extended periods of time. Given that each and every COPV used in spacecraft is proof tested before entering service and any weight savings on a spacecraft results in significant cost savings, this thesis put forward an application of RBDO that accounts for proof test data in the design of a COPV. The method developed in this thesis shows that, while maintaining high levels of reliability, significant weight savings can be achieved by including proof test data in the design process. Also, the method enables a designer to have control over the magnitude of the proof test, making it possible to also design the proof test itself depending on the desired level of reliability for passing the proof test. The implementation of the method is discussed in detail. The evaluation of the reliability was based on the First Order Reliability Method (FORM) supported by Monte Carlo Simulation. Also, the method is implemented in a versatile way that allows the use of analytical as well as numerical (in the form of finite element) models. Results show that additional weight savings can be achieved by the inclusion of proof test data in the design process.
AFRIKAANSE OPSOMMING: Onlangse studies het getoon dat die gebruik van ontwerp spesifieke proeftoets data in betroubaarheids gebaseerde optimering (BGO) kan lei tot 'n verbeterde ontwerp. BGO behels vele aspekte in die ontwerpsgebied. Die toevoeging van proeftoets data in ontwerpsoptimering bring te weë; die toetsing van 'n ontwerp en onderdele voor gebruik, die aangepaste en verbeterde ontwerp en gewig-besparing met handhawing van hoë betroubaarsheidsvlakke. 'n Praktiese toepassing van die BGO tegniek behels die ontwerp van drukvatte met saamgestelde materiaal bewapening. Die drukvatontwerp is 'n ligte struktuur wat gebruik word in die berging van hoë druk vloeistowwe in bv. in ruimtetuie, in die internasionale ruimtestasie en in ander toepassings waar hoë druk oor 'n tydperk verlang word. Elke drukvat met saamgestelde materiaal bewapening wat in ruimtevaartstelsels gebruik word, word geproeftoets voor gebruik. In ruimte stelselontwerp lei massa besparing tot 'n toename in loonvrag. Die tesis beskryf 'n optimeringsmetode soos ontwikkel en gebaseer op 'n BGO tegniek. Die metode word toegepas in die ontwerp van drukvatte met saamgestelde materiaal bewapening. Die resultate toon dat die gebruik van proeftoets data in massa besparing optimering onderhewig soos aan hoë betroubaarheidsvlakke moontlik is. Verdermeer, die metode laat ook ontwerpers toe om die proeftoetsvlak aan te pas om sodoende by ander betroubaarheidsvlakke te toets. In die tesis word die ontwikkeling en gebruik van die optimeringsmetode uiteengelê. Die evaluering van betroubaarheidsvlakke is gebaseer op 'n eerste orde betroubaarheids-tegniek wat geverifieer word met talle Monte Carlo simulasie resultate. Die metode is ook so geskep dat beide analitiese sowel as eindige element modelle gebruik kan word. Ten slotte, word 'n toepassing getoon waar resultate wys dat die gebruik van die optimeringsmetode met die insluiting van proeftoets data wel massa besparing kan oplewer.
Zhao, Liang. "Reliability-based design optimization using surrogate model with assessment of confidence level." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/1194.
Gaul, Nicholas John. "Modified Bayesian Kriging for noisy response problems and Bayesian confidence-based reliability-based design optimization." Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/1322.
Dersjö, Tomas. "Methods for reliability based design optimization of structural components." Doctoral thesis, KTH, Hållfasthetslära (Avd.), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-90753.
QC 20120229
Chen, Qing. "Reliability-based structural design: a case of aircraft floor grid layout optimization." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39630.
Mahadevan, Sankaran. "Stochastic finite element-based structural reliability analysis and optimization." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/19517.
Bouguila, Maissa. "Μοdélisatiοn numérique et οptimisatiοn des matériaux à changement de phase : applicatiοns aux systèmes cοmplexes." Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMIR05.
Phase-change materials exhibit considerable potential in the field of thermal management.These materials offer a significant thermal storage capacity. Excessive heat dissipated by miniature electronic components could lead to serious failures. A cooling system based on phase-change materials is among the most recommended solutions to guarantee the reliable performance of these microelectronic components. However, the low conductivity of these materials is considered a major limitation to their use in thermal management applications. The primary objective of this thesis is to address the challenge of improving the thermal conductivity of these materials. Numerical modeling is conducted, in the first chapters, to determine the optimal configuration of a heat sink, based on the study of several parameters such as fin insertion, nanoparticle dispersion, and the use of multiple phase-change materials. The innovation in this parametric study lies in the modeling of heat transfer from phase-change materials with relatively high nanoparticle concentration compared to the low concentration found in recent literature (experimental researchs). Significant conclusions are deducted from this parametric study, enabling us to propose a new model based on multiple phase-change materials improved with nanoparticles (NANOMCP). Reliable optimization studies are then conducted. Initially, a mono-objective reliability optimization study is carried out to propose a reliable and optimal model based on multiple NANOMCPs. The Robust Hybrid Method (RHM)proposes a reliable and optimal model, compared with the Deterministic Design Optimization method (DDO) and various Reliability Design Optimization methods (RBDO). Furthermore,the integration of a developed RBDO method (RHM) for the thermal management applicationis considered an innovation in recent literature. Additionally, a reliable multi-objective optimization study is proposed, considering two objectives: the total volume of the heat sink and the discharge time to reach ambient temperature. The RHM optimization method and the non-dominated sorting genetics algorithm (C-NSGA-II) were adopted to search for the optimal and reliable model that offers the best trade-off between the two objectives. Besides, An advanced metamodel is developed to reduce simulation time, considering the large number of iterations involved in finding the optimal model
Patel, Jiten. "Optimal design of mesostructured materials under uncertainty." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31829.
Committee Chair: Choi, Seung-Kyum; Committee Member: Muhanna, Rafi; Committee Member: Rosen, David. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Ren, Xuchun. "Novel computational methods for stochastic design optimization of high-dimensional complex systems." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/1738.
Johansson, Cristina. "On System Safety and Reliability Methods in Early Design Phases : Cost Fo cused Optimization Applied on Aircraft Systems." Licentiate thesis, Linköpings universitet, Maskinkonstruktion, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-94354.
Zhang, Peipei. "Diffuse response surface model based on advancing latin hypercube patterns for reliability-based design optimization of ultrahigh strength steel NC milling parameters." Compiègne, 2011. http://www.theses.fr/2011COMP1949.
Since variances in the input parameters of engineering systems cause subsequent variations in the product performance, and deterministic optimum designs that are obtained without taking uncertainties into consideration could lead to unreliable designs. Reliability-Based Design Optimization (RBDO) is getting a lot of attention recently. However, RBDO is computationally expensive. Therefore, the Response Surface Methodology (RSM) is often used to improve the computational efficiency in the solution of problems in RBDO. In this work, we focus on a Response Surface Methodology (RSM) adapted to the Reliability-Based Design Optimization (RBDO). The Diffuse Approximation (DA), a variant of the well-known Moving Least Squares (MLS) approximation based on a progressive sampling pattern is used within a variant of the First Order Reliability Method (FORM). The proposed method simultaneously uses points in the standard normal space (U-space) as well as the physical space (X-space). The two grids form a “virtual design of experiments” defined by two sets of points in the two design spaces, that are evaluated only when needed in order to minimize the number of ‘exact’ thus computationally expensive function evaluations. In each new iteration, the pattern of points is updated with points appropriately selected from the “virtual design of experiments”, in order to perform the approximation. As an original contribution, we introduce the concept of « advancing Latin Hypercube Sampling (LHS) » which extends the idea of Latin Hypercube Sampling (LHS) to maximally reuse previously computed points while adding a minimal number of new neighboring points at each step, necessary for the approximation in the vicinity of the current design. We propose panning, expanding and shrinking Latin hypercube patterns of sampling points and we analyze the influence of this specific kind of patterns on the quality of the approximation. Next we calculate the minimal number of data points required in order to get a well-conditioned approximation system. In the application part of this work, we investigate the optimization of the process parameters for Numerical Control (NC) milling of ultrahigh strength steel. The success of the machining operation depends on the selection of machining parameters such as the feed rate, cutting speed, and the axial and radial depths of cut. A variant of the First Order Reliability Method (FORM) is chosen to calculate the reliability index. The optimization constraints are expressed as functions of the computed reliability indices
Price, Nathaniel Bouton. "Conception sous incertitudes de modèles avec prise en compte des tests futurs et des re-conceptions." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEM012/document.
At the initial design stage, engineers often rely on low-fidelity models that have high uncertainty. In a deterministic safety-margin-based design approach, uncertainty is implicitly compensated for by using fixed conservative values in place of aleatory variables and ensuring the design satisfies a safety-margin with respect to design constraints. After an initial design is selected, high-fidelity modeling is performed to reduce epistemic uncertainty and ensure the design achieves the targeted levels of safety. High-fidelity modeling is used to calibrate low-fidelity models and prescribe redesign when tests are not passed. After calibration, reduced epistemic model uncertainty can be leveraged through redesign to restore safety or improve design performance; however, redesign may be associated with substantial costs or delays. In this work, the possible effects of a future test and redesign are considered while the initial design is optimized using only a low-fidelity model. The context of the work and a literature review make Chapters 1 and 2 of this manuscript. Chapter 3 analyzes the dilemma of whether to start with a more conservative initial design and possibly redesign for performance or to start with a less conservative initial design and risk redesigning to restore safety. Chapter 4 develops a generalized method for simulating a future test and possible redesign that accounts for spatial correlations in the epistemic model error. Chapter 5 discusses the application of the method to the design of a sounding rocket under mixed epistemic model uncertainty and aleatory parameter uncertainty. Chapter 6 concludes the work
Slowik, Ondřej. "Pravděpodobnostní optimalizace konstrukcí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226801.
Lin, Shu-Ping, and 林書平. "Parallelized Ensemble of Gaussian-based Reliability Analyses (PEoGRA) for Reliability-Based Design Optimization (RBDO)." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/04249081892380031251.
中原大學
機械工程研究所
104
Reliability-Based Design Optimization (RBDO) algorithms have been developed to solve design optimization problems with existence of uncertainties. Traditionally, the original random design space is transformed to the standard normal design space, where the reliability index can be measured in a standardized unit. In the standard normal design space, the Modified Reliability Index Approach (MRIA) measured the minimum distance from the design point to the failure region to represent the reliability index; on the other hand, the Performance Measure Approach (PMA) performed inverse reliability analysis to evaluate the target function performance in a distance of reliability index away from the design point. MRIA was able to provide stable and accurate reliability analysis while PMA showed greater efficiency and was widely used in various engineering applications. However, the existing methods cannot properly perform reliability analysis in the standard normal design space if the transformation to the standard normal space does not exist or is difficult to determine. Especially, in image processing application, the transformation is hard to determine because of arbitrarily distribution in CIELAB space. The program speed is important while image processing application algorithm developed. To this end, a new algorithm, Parallelized Ensemble of Gaussian Reliability Analyses (PEoGRA), was developed to estimate the failure probability using Gaussian-based Kernel Density Estimate (KDE) in the original design space. The probabilistic constraints were formulated based on each kernel reliability analysis for the optimization processes. And Muti-Thread shared memory framework, including data access layer, assigned task layer and layer of estimation of reliability index layer, is used to acceleration program. This paper proposed an efficient way to estimate the constraint gradient and linearly approximate the probabilistic constraints with fewer function evaluations. Some numerical examples with various random distributions are studied to investigate the numerical performances of the proposed method. The program speed is investigated with EoGRA and PEoGRA in numerical examples also. Above of all, the results showed PEoGRA is capable of finding correct solutions in some problems that cannot be solved by traditional methods. PEoGRA is capable to operate image processing application in acceptable speed.
Smith, SHANE. "Reliability of Deterministic Optimization and Limits of RBDO in Application to a Practical Design Problem." Thesis, 2008. http://hdl.handle.net/1974/1410.
Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2008-09-05 10:51:26.273
Biton, Nophi Ian Delos Reyes, and Nophi Ian Delos Reyes Biton. "Reliability-based Design Optimization using Methods of Moments." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/10121101336303007497.
國立臺灣科技大學
營建工程系
105
Reliability-based Design Optimization (RBDO) produces optimal design with minimal cost and ensures a more reliable performance of the structure by explicitly incorporating uncertainties in its optimization algorithm. Expensive computational cost, accuracy of reliability assessment, as well as nonlinearity and non-differentiability of performance function are the main challenges in performing RBDO in real engineering problems. The promising accuracy and efficiency of Methods of Moments such as simplified third-moment (3M), fourth-moment (4M) and Pearson’s Distribution System-based fourth-moment (4M-P) for probabilistic analysis in combination with a metaheuristic optimization algorithm (i.e. Particle Swarm Optimization, PSO) is explored for RBDO implementation. The proposed methodology was able to search for the optimal design having linear, highly nonlinear, and implicit performance functions considered in the probabilistic constraints which were demonstrated in several numerical examples. To emphasize the applicability of the proposed algorithm in practical engineering problems, a two bay three story steel structure were solved, in which an equivalent stick model was developed to further lessen the computational cost in nonlinear time history analyses. The results were validated and compared from gathered related literature. The limitation on the applicable range of the simplified Methods of Moments produced incorrect optimal design in the RBDO for highly nonlinear limit state functions and non-normal random variables. However, for normally distributed random variables, simplified Methods of Moments formulations showed improved accuracy in structural reliability at optimal design compared to other existing reliability methods. Also, by increasing the number of variates in dimension reduction method, more accurate estimation of the moments of the performance function was observed. Finally, the implications of the results and limitations of the methodology are discussed
(5930906), Jacob J. Torres. "The Biowall Field Test Analysis and Optimization." Thesis, 2019.
A residential botanical
air filtration system (Biowall) to investigate the potential for using
phytoremediation to remove contaminants from indoor air was developed. A full scale and functioning prototype was
installed in a residence located in West Lafayette, Indiana. The prototype was integrated into the central
Heating, Ventilating, and Air Conditioning (HVAC) system of the home. This
research evaluated the Biowall operation to further its potential as an energy
efficient and sustainable residential air filtration system.
The main research effort began after the Biowall was installed in the residence. A field evaluation, which involved a series of measurements and data analysis, was conducted to identify treatments to improve Biowall performance. The study was conducted for approximately one year (Spring 2017-Spring 2018). Based on the initial data set, prioritization of systems in need of improvement was identified and changes were imposed. Following a post-treatment testing period, a comparison between the initial and final performances was completed with conclusions based on this comparison.
The engineering and analysis reported in this document focus on the air flow path through the Biowall, plant growth, and the irrigation system. The conclusions provide an extensive evaluation of the design, operation, and function of the Biowall subsystems under review.