Design, Modeling and Experimental Validation of a Variable Resonant Electro-Hydraulic Fatigue Testing System

High frequency excitation in the electro-hydraulic mode, especially kilohertz regime, has already been realized owing to the merits of specially designed two-dimensional rotary valve (2D rotary valve). However, some sacrifice in the excitation amplitude is inevitable as pursuing the higher excitation frequency. A scheme for an electro-hydraulic excitation system working at resonant is proposed, which could accomplish high excitation frequency and large vibration amplitude simultaneously. More specifically, the resonant frequency of this system can be regulated as loads of the excitation system, which would greatly facilitate fatigue testing of different elastomeric materials. This paper investigates more details of the excitation characteristics in whole frequency domain, including non-resonance and variable resonance. The excitation waveforms, variable resonant frequency and resonant peak are derived and validated by experimental data. This work provides clear analytical expressions of the mathematical model, offers important guidance for the design of the system, and paves the way for the potential engineering application of the variable resonant excitation technology.