Advancements in electrohydraulic fatigue testing: Innovations in variable resonance frequency control and comprehensive characterization

Abstract

This study addresses the challenge in electro-hydraulic fatigue testing machines where increasing excitation frequency leads to reduced output load amplitude, making it difficult to optimize both frequency and amplitude simultaneously. A new approach is introduced with the variable resonance fatigue testing machine controlled with 2D excitation valves. This technique involves adjusting the system’s intrinsic frequency by altering its mass, aligning the excitation frequency with the intrinsic frequency, and leveraging resonance energy to enhance excitation amplitude for broad-range resonance near the resonance point. The relationship between the system’s intrinsic frequency, the equivalent mass of the upper connector, and the upper fixture is explored, yielding analytical solutions. Experimental research validates these simulations, in the resonance condition, the fatigue testing machine energy efficiency can reach 94 %, to further verify the fatigue testing machine in the resonance condition to realize the High energy efficiency. Demonstrating that the system’s intrinsic frequency decreases with increasing mass, allowing for a broad frequency resonance between 200 and 300 Hz. Operating in a broadband resonance region, the output load force is increased by 60 %–95 % and the system flow is reduced by 20 %–30 %. This mass-adjustment technique effectively alters the system’s intrinsic frequency, expanding the electro-hydraulic fatigue testing machine’s application scope.