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Development of Hydraulically Driven Fatigue Testing Machine for Insulators

The hydraulically driven fatigue testing machine is studied to simulate the vibration in the fatigue experiments for the insulators. First, hydraulic scheme and control principle are introduced. A special composite cylinder is designed, which is controlled by a servo valve and a proportional relief valve to generate static and dynamic tensional force. Then, models of electro-hydraulic subsystems are analyzed. For the actual needs of the dynamic tensional force system, a high-fidelity force source is of great significance. Considering parameter uncertainty and a high bandwidth of the servo valve pressure dynamics, there is a need to improve the bandwidth of the flow type servo valve as far as possible. Taking into account the limitations of general approaches, this paper proposes load velocity feedback to solve the challenging control issues, which mainly solves the problem of response bandwidth. Finally, a new system controller is designed, and some experiments are developed to verify the feasibility of system principle and the effectiveness of control algorithm. The hydraulically driven fatigue testing machine based on the discussed electro-hydraulic technology has been developed, with satisfactory technical specifications.