Electro-hydraulic Control Of The Hydraulic System Of The Impact Testing Machine

Both manufacturers and users are giving their more attention to the shock resistance of products nowadays, which is a important constituent of its reliability, and shock testing is a indispensable means of checking resistance to impact. To. improve the level of shock test, improving and strengthening the performance of the shock machine is an important research objective. Against the disadvantages that existing in current mechanical shock testers, the thesis mainly presents a new-type structure of electro-hydraulic control shock tester and makes much study and analysis on it. It is consisting of six sections as follow.Chapter 1 first introduces the development-history, present state on the research and application of product shock testers, the current application situation of shock teasing and its force pulse on the base of having collected and analyzed plenty of documentation. Then it states the general development situation and research trends on the force pulse generator, and the present status of electro-hydraulic proportional/servo control technique. In the end this thesis points out the main content and significance of the research work.Chapter 2 derives the acceleration, velocity, and displacement functions of the three force pulse waveforms and states the generation course of corresponding wave profile in its first section. And then puts forward a new-type force pulse generator that is integrated from accumulator, hydraulic cylinder, valve and specifies the mechanical structure of electro-hydraulic proportional/servo system. Furthermore it analyzes and deduces the both the calculatior formula of stiffness coefficient on the pneumatic spring in the accumulator, and the formulas of the acceleration, velocity, displacement, and maximum speed on the piston in the hydraulic cylinder being controlled by a valve. The last part of the chapter illustrates and analyses the structural principle of large-capacity control valve.Chapter 3 analyses the design of shock tester system composed of accumulator, hydraulic cylinder, and valve through computer simulation software Matlab6.1, including firstly the modeling of system control structure, secondly the modeling and simulation on the dynamic process of accumulator and hydraulic cylinder controlled by valve, and the force characteristic and dynamic response of large-capacity proportional valve, then summarizes the relation between product characteristic and several main structural parameters. In the last part of the section it calculates and analyses the work process of whole integrated component.Chapter 4 firstly analyses the generation mechanics, calculating method and interference effect of flow force in the outflowing large-capacity proportional valve. Then it not only presents a structural design to compensate the flow force according to the performance characteristic of the cone valve, but also calculates and simulates the flow field at the valve port through CFD software Fluent6.0. At last it studies the influence of compensation structure parameters and obtains better projected dimensions.Chapter 5 firstly introduces the experiment platform design of accumulator-valve -hydraulic cylinder system and testing method. Then it summarizes and analyses the experiments result and obtains some valuable conclusions. It has laid the foundation for future research and development of electro-hydraulic control shock tester.Chapter 6 summarizes the whole thesis.