Candidate: Gilson Simões Porciúncula
Program: UFSC / POSMEC
Date: May, 2009
Advisor: Victor Juliano De Negri
Co-advisor: Acires Dias (NeDIP / UFSC)
Abstract: Automatic systems have as features the use of different technologies and the execution of multiple independent functions. These systems comprise mechanical, electric, electronic components and software as well. Such features are established during the design process and documented through structural, functional, behavioral models. An automatic system design process presents inherent difficulties and usually demands specialized professionals for each technology involved. Therefore, their reliability analysis, considering all the particularities involved, may become a complex task. Also, especially when it comes to hydraulic and pneumatic systems, the great number of components and the need for information exchange between different technological areas should be considered. This thesis present a methodology that results in the generation of the reliability model and the calculation of the reliability index of automatic systems during the design process, in order to improve the system’s competitiveness in markets demanding precision in the performance of devices, assured functioning and easy maintenance. In this fashion, this thesis is developed within the bounds of the design process of automatic systems, mainly focused on hydraulic and pneumatic systems, since it evaluates reliability during the conceptual phase of design process. The proposed methodology allows gathering information from structural, functional and behavioral models during the early phases of the design process. The Methodology for Analysis of Automatic Systems’ Reliability (MACSA) which takes into account the interactions of different technological areas of automatic systems, as well as different functional arrangements defined in the system during its useful life. MACSA was structured in a systematic form and inserted in an integrated product design methodology. The proposed methodology was evaluated on two case studies: a hydraulic power and conditioning unit and a didactic pneumatic test bench applied for the sizing of general pneumatic systems. In order to implement the proposed methodology modeling and reliability analysis tools, such as Channel/Instance Net, Grafcet, Petri Nets, Fault Tree and Success Tree, were used. The case studies’ practical results demonstrated that MACSA considers more realistic situations for automatic systems reliability evaluation. By so, the adoption of the presented methodology contributes for an improvement of reliability evaluation during the automatic systems’ design process. These aid designers in making decisions about the best conception for their final design, making the resulting automatic systems more reliable, and yielding a faster and cheaper design process.
PORCIÚNCULA, G. S. Metodologia para análise de confiabilidade no projeto de sistemas automáticos. 2009. Tese (Doutorado em Engenharia Mecânica) 168 p. Universidade Federal de Santa Catarina: Florianópolis.