Design And Research On The Control System Of Electro-hydraulic High-frequency Fatigue Test Machine

Electro-hydraulic high-frequency fatigue test machine is widely used in aerospace, military, transportation, construction machine and other fields for its fast response speed, big output power, high control precision and low alternating load waveform distortion.Based on electro-hydraulic high-frequency fatigue test machine,by improving its mechanical structure to increase the fatigue test performance to make it has the high frequency test ability.It is mainly composed by upper chuck position synchronous controller and high-frequency vibrator.Because the high-frequency vibrator is the core of the excitation device,research on the high frequency vibrator and its control technology is necessary.In order to solve the problem of traditional servo valve can not meets the requirement of high frequency vibration control, a special structure of 2D high-frequency valves is designed.This 2D high-frequency valve has two dimensions, can achieve high-frequency excitation and excitation amplitude value control.At the same time, a 2D digital valve is parallel on the double rod hydraulic cylinder,in order to control the vibration center of the high-frequency vibrator.On the basis of modifying the mechanical structure,design a control system to control the high-frequency vibrator.The main content of the thesis are as follows:1. Analysis the overall structure and working principle of the electro-hydraulic fatigue testing machine;introduce the working principle of the upper chuck position synchronous controller and high-frequency vibrator.Because the high frequency vibrator is the core component of the electro-hydraulic high-frequency fatigue test machine,analyses the structure and working principle of 2D high-frequency valve and 2D digital valve.2. Simulate the model of high-frequency vibrator. Analysis the simulation results;provide theoretical support on designing the electro-hydraulic high-frequency fatigue test machine and its control system.3. Analysis the control characteristic of high-frequency vibrator;design and analysis the control system,divide it to vibration frequency controller,vibration amplitude controller,bias controller and Single rod hydraulic cylinder controller.4.,Build the experiment platform of high-frequency fatigue test machine,do experiments on vibration frequency, vibration amplitude and bias control.The experiments shows that the control system can effectively control electro-hydraulic high-frequency fatigue test machine working in 1000 Hz for high frequency and large load fatigue test, the load of 2500 Hz power can achieve 3kN.