Study On Electro-Hydraulic Control System For Fatigue Testing Machine Of Highway Concrete

Concrete is extensively applied in road construction such as expressway, overhead way, the overpass and bridge, etc. Nowadays, the phenomenon that vehicles are overloaded with goods is comparatively general in our country. The concrete pavement needs to bear the repeated fatigue load brought by the vehicles, and lead to the fact the pavement will be destroyed earlier than anticipation. It influenced the communications and transportation seriously, sometimes will cause the great economic losses and even threaten the security of life. So pavement construction and new-type concrete research need to measure their performance of resisting fatigue load, evaluate their quality, in order to put it into use rationally, guarantee life and property safely. The testing machine that can imitate the fatigue load of vehicle press on the highway concrete will become key equipment.This paper analyses the characteristics of the reversal stress in highway concrete generated by vehicle load, and uses approach such as theoretical research, computer emulation combine with simulated test. Having designed a electro-hydraulic servo control system, including the principle design of hydraulic system and calculations of its main components, and the systematic match in hydraulic system. A measurement & control system is designed to exert periodic load to the specimen in term of preestablished rules.After having analyzed the transmission function of the servo valve and derived the transmission function of symmetrical cylinder controlled by servo valve, the mathematics model of electro-hydraulic servo control system is set up. Then carry on research to the controller. The PID controller can dispel the stable error while fuzzy controller has excellent adaptation. So we can make the PID parameter melt fuzzily, and design a fuzzy parameter adaptive PID controller with MATLAB fuzzy toolbox.A simulation model of control system is set up with SIMULINK, then use PID controller, fuzzy controller and fuzzy parameter self-adaptive PID for step respond and sine-wave-followed one by one. The result cures show the good performances of the fuzzy parameter self-adaptive PID controller. Finally, the author build a simulated testing platform, design the hydraulic circuit and measurement & control system, and write controlling software. The result shows that the simulated testing platform can exert periodic load to specimen according to preestablished rules.