Candidate: Rodrigo Simões Lopes Junior 
Program: UFSC / POSMEC
Date: November, 2021
Advisor: Victor Juliano De Negri
Abstract: This Master’s thesis presents an analysis of the dynamic behavior of a Digital Hydraulic Actuator – DHA designed for flight control purposes under a failure condition. The hydraulic technology is widely used for controlling flight surfaces in aircraft and the traditionally approach for this purpose is the control by servo or proportional valves. Nevertheless, the low energy efficiency of the conventional solutions, due to the resistive effects and internal leakage, has been motivating the development of new solutions that increasing the energy saving. In thisbscenario, the new researches on Digital Hydraulic Systems have shown the great potential of this technology to combine the well-established and robust performance of the hydraulic technology with high levels of energy efficiency. Nowadays, just a few studies are found about the DHA performance under a failure conditions, and also about their ability to reconfigure itself and increase the system’s fault tolerance, one of the main requirements for aeronáutical applications. The initial studies for the DHA conception under failure conditions showed that the actuator loses some discrete forces values, which can compromise their operational performance and reliability. Until now, a system failure reconfiguration strategy had not yet been formalized, and it is not known, therefore, if the system would be capable to meet the operational requirements and guaranteeing the functional redundancy. The results presented in this Master’s thesis comprise a series of analyzes that were carried out for the DHA concept, which allow an overview of the DHA behavior under failure conditions in order to better understand the functional redundancy requirements. Experimental tests at LASHIP’s Digital Hydraulic test rig which comprises a DHA prototype were carried out and also simulations with validated mathematical models of the actuators were applied in a fighter aircraft model. The results of this Master’s thesis adds to the set of previous works developed throungh the Brazil-Sweden partnership involving LASHIP-UFSC, FLUMES-LIU, CERTI, and SAAB AB, which has been showing promising results in Digital Hydraulics solutions for aerospace purposes, and receiving international recognition in this theme.
Reference: LOPES, R. S. Jr. Avaliação do Desempenho Dinâmico de um atuador hidráulico Digital para Aplicações Aeronáuticas em Condição de Falha. 2021. 153 p. Dissertação (Mestrado em Engenharia Mecânica). Universidade Federal de Santa Catarina, Florianópolis, 2021.
