The Life Analysis Of Pneumatic Cylinder Based On Fatigue Failure Test

Owing to its safety performance, low power consumption, non-pollution, easymaintenance and other characteristics, pneumatic cylinders are being widely used invarious walks of life, such as manufacture industry, electronic IC industry, aviationindustry and etc. For the past few years, with the rapid development of pneumaticproducts, the application domain of pneumatic products extends continuously. Therefore,it is particularly important to provide safe and reliable cylinders. This project will dofatigue failure test of the cylinders, with the establishment of pneumatic test platform，aiming at the exploration of failure mode and it’s working life. By fully grasp of thecylinder’s characteristics and their failure mode, excessive design could be avoided andproduct costs could be reduced effectively.In the first place, this thesis introduces the current situation of pneumatictechnology and the researches domestically and internationally, explores the process andmechanism of fatigue damage. Combined with the project assignment, the fatiguefailure test programme is presented. Besides, with the reference of the cylinderinternational standards, we would summarize the failure fault tree of cylinder and wewill focus on the changes of leakage rate, travel time and minimum working pressureduring the fatigue failure test.Then, the pneumatic test platform is introduced, including the design andimplementation of pneumatic system and electric control system, as well as the fatiguefailure test process and some data testing methods. According to the test data, thevariation trend and changing reason of cylinder’s leakage rate, travel time and minimumworking pressure are analyzed, which would propose that excessive leakage could beone of the main failure modes. Some fatigue failure modes of cylinder is summarized byanalyzing the cylinder failure samples.In addition, the cylinder pressure and displacement waveform is obtained duringthe process of test and then model and simulate for the running cylinder based onpractical situation to get the simulation waveform. By comparing these two results, found that these curves are basically accordant, which illustrate that they are running ingood condition.Finally, the stress cloud chart of the cylinder during the process of piston collidecylinder cover is analyzed with simulation software. The simulation results show thatthe largest stress present at the cylinder feet frame and bolt, which coincides with thefailure samples. Combined with some existing experimental data and simulation result,some feasible measures of improving the cylinder working life are proposed.