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| Author(s): |
Wellison José de Santana Gomes
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD) |
| Defense date: | 2013-03-07 |
| Examining board members: |
André Teófilo Beck;
Edson Denner Leonel;
Fernando Alves Rochinha;
Luis Volnei Sudati Sagrilo;
Marcelo Areias Trindade
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| Advisor: | André Teófilo Beck |
| Abstract | |
Random corrosion and fatigue processes reduce slowly but gradually the resistance of structures and mechanical components, leading to gradual increase in failure probabilities. Risk management for mechanical components subject to corrosion and fatigue is made by means of policies of inspection, maintenance and substitution. These activities imply costs, but are made to maintain the reliability at acceptable levels, while the component remains in operation. Apparently, economy and safety are competing objectives; however, reduction in inspection and maintenance spending may lead to larger failure probabilities, increasing expected costs of failure (risk). Risk optimization allows one to solve this problem, by means of the so-called total expected cost. In this Thesis, risk optimization is used in order to find the best inspection and maintenance policy, i.e., the proper amount of resources to allocate to such activities in order to obtain minimum total expected cost. Corrosion and fatigue are modeled by means of polynomial chaos expansions, using a novel approach developed herein and experimental or observed data obtained from the literature. These models are employed within two risk optimization problems, solved for different failure and inspection cost configurations. Results show that the optimal policies of inspection, maintenance and replacements can be very different, for different cost configurations, and that the solution of the associated risk optimization problems is a very challenging task, due to the large number of local minima, caused by discontinuities and fluctuations in the total expected costs. (AU) | |
| FAPESP's process: | 09/17365-6 - Risk optimization under random fatigue and corrosion processes |
| Grantee: | Wellison José de Santana Gomes |
| Support Opportunities: | Scholarships in Brazil - Doctorate |