Abstract: Ultimate performance research of electro-hydraulic load simulator is affected by the fact that the traditional model lacks adequate precision. Therefore, a complex mathematical model of electro-hydraulic load simulater is built which includes a multi-stiffness model and several nonlinear factors. The multi-stiffness model is based on the stiffness of aircraft actuator, load, torque sensor, and loading motor shaft. Nonlinear factors are considered in the system, such as saturation, friction, and the nonlinear flow characteristics of the servo valve. Through simulation and analysis, a comparison is made between the traditional model and the complex model. Based on the results of simulation and experiment with the input of load profile to the electro-hydraulic load simulater, the complex mathematical model is proved to be more accurate in reflecting the real physical situation of the electro-hydraulic load simulater system. The proposed model may be of theoretical value to the optimization of design of structure parameters and the research on control strategy.

Key words: hydraulics, electro-hydraulic load simulators, models, nonlinear systems, stiffness, ultimate performance