| Actually, bellows mostly work under non-proportional and multi-axial load conditions. Thus, if the traditional fatigue machine was used, the prediction of bellows fatigue damage based on uniaxial fatigue theory cannot reach sufficient accuracy and satisfy the requirements. So, for the bellows are widely used, develop a new fatigue machine which can be fully close to the actual condition of the bellows has more significance for researchers to make in-depth study of multi-axial fatigue mechanism about bellows, to find ways to improve fatigue resistance and to predict multi-axial fatigue life accurately. This paper designed a closed loop electro-hydraulic proportional control system which fully integrated electrical and hydraulic advantages of both. The system has good control performance, big drive capacity, and easy to be controlled by computer. It can simulate the actual working conditions of bellows and improve the control precision of fatigue machine on bellows.Firstly, a test mechanism is designed based on the working condition characteristic of the bellows, electro-hydraulic proportional closed control system is designed based on the test requirements to hydraulic system in this paper and the dynamic mathematic model of the hydraulic system is built. In addition, the dynamic characteristics of the system are analyzed in detail by means of the knowledge of control theory. And then toward to the dynamic response characteristics of the system, PID controller is adopted to correct the system, and have improved the dynamic quality of the system. In this paper, the hydraulic system is simulated on the basis of the Matlab/Simulink and DSHplus two kinds of simulation software and the results of simulation prove that the qualities of the system can satisfy with the practical requirement very well, and by contrast, it highlights the advantages of DSHplus that the professional hydraulic simulation software.Be to realize the fine man-machine interface, VB is made use of to program as platform and data administration, by which we can setup and amend technologic parameter handily. save history note, and display displacement curve of piston real time. In addition. PCL-812PG industry board is adopted as hardware interface to complete data collection and data output and so on in the paper. |
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