Abstract: Electro-hydrostatic actuator(EHA) is a key component of flight control actuator system of civil aircraft. Its failure mode and effect are the focus of airworthiness certification and compliance verification. In current engineering practice, linearizing the components in the EHA system will ignore the influence of nonlinear factors in the system on the fault performance. Basing on AMESim simulation platform and considering the nonlinear factors of stiffness and connection clearance, EHA system nonlinear model is established. Simulation analysis is carried out to explore the influence of nonlinear factors such as stiffness and connection clearance on the leakage fault in hydraulic cylinder. Results show that stiffness reduces the magnitude of leakage fault in hydraulic cylinder but causes periodic vibration while stiffness has significant influence on the leakage in hydraulic cylinder. Nonlinear factors significantly affect EHA system failure performance, which provides technical support for airworthiness certification and compliance verification of EHA system.

Key words: electro-hydrostatic actuator(EHA), nonlinear factor, fault simulation