Design And Study Of Type PL50 Electro-hydraulic Servo Fatigue Testing Machine

As a kind of test equipments, the electro-hydraulic servo fatigue testing machine plays an important role in material test, development of new materials, product design, supervision of product quality and quality control. It involves lots of fields such as mechanism, hydraulics, electron, material science, measurement, automation and so on. What's more, it colligates high technique such as latter-day closed loop servo, digital display, electro-mechanical integration and computer, so it possesses very strong interdiscipline. With the development of the modern science and technology, the dynamic fatigue test is laid on more attention, the whole level of fatigue testers is advanced continually. It has been the essential equipment for partial fatigue strength and life testing in mechanical industries such as plane, automobile etc.The text briefly introduces hydraulic and electric control system of the fatigue testing machine. According to the requirement of the system design, the text disigns the system skeleton drawing, calculates the major parameters of the system. With the model of the valve-controlled symmtery cylinder, each segment feature is analyzed, the system tranfer function is built and the system stability is analyzed.The performance of the electro-hydraulic servo fatigue testing machine depends on the control system. The theory of the routine PID control is simply and prone to realize, but the overshooting is very large, it's difficult to realize accurate control for nonlinear system. However, the self-adaptive fuzzy PID controller bases on expert system, it can finish on-line self-regulation and self-optimisum to PID parameters. In the performance aspect of the system dynamic and static states, it gets a better control effect, the control accuracy is very high. The self-adaptation and self-study function are comparely strong.The text adopts series S7-200 PLC of Siemens enterprise, with the structure compactive, the function strong and the performance-to-price ratio high. Series S7-200 PLC is used to proceed electric control, the module CPU224 and the expanded module EM223 are chosen according to the system congtrol functon. The programme software STEP 7-Micro/WIN V4.0 is utilized to draw the ladder diagram, realizes the electric function of sequential control.