| Hydraulic damping cylinder,also known as hydraulic damper,is a common damping element.It is mainly used for damping and buffering,protecting the system from mechanical failure caused by external impact,and improving the stability of system.It is widely used in medical machinery,engineering machinery,bridge construction and other fields.In order to test the life index of products and the quality of manufacturing,it is of great significance to design and research a hydraulic damping cylinder fatigue test platform.Based on the analysis of the research status of the hydraulic damping cylinder test platform at home and abroad,the overall control scheme and structure scheme of the test platform are determined according to the main fatigue test functions and the design requirements,including the transmission structure of the test platform,the fixture structure of the tested damping cylinder and data acquisition scheme,etc.,and the design and selection of the motor,module,sensor and other purchased parts as well as the supporting control system hardware are checked with analysis and carried out.This thesis selected LabVIEW software as the development platform of control system,and built the control system software of hydraulic damping cylinder fatigue test platform.According to the functional requirements,the human-computer interface of the software is designed,and the software is divided into three modules: human-computer interaction,motor monitoring and control and data acquisition and storage.According to the interaction characteristics between this modules,using the design patterns of Event Hander Loop and Actor,the back panel of the three modules is designed and implemented in detail.According to the fatigue test function of the test platform,this paper analyzes the variation relationship between the internal leakage and the equivalent damping coefficient when the hydraulic damping cylinder leaks.Simulation module of related simulation software is used to build the system simulation model,and the variation relationship is used to simulate the degree of internal leakage for simulation test.A fault feature extraction method based on wavelet analysis is used to analyze the output of the simulation force sensor,and several fault feature monotonically varying with the internal leakage degree are obtained,After analysis and comparison,this thesis selected the normalized wavelet packet energy of low frequency signal as the judgment feature,and estimated the threshold value.A fault early warning method based on LabVIEW software is proposed,and the design and implementation of the software function module are carried out.Based on all the mechanical,hardware and software design and theoretical research,this thesis carried out the experimental verification and debugging of the whole machine on site,including the measurement verification experiment of the test platform structure index,the offline debugging experiment of LabVIEW program,the functional verification experiment of fatigue test and pressure-tight test of the test platform,and the functional verification experiment of the fault early warning function.Through debugging and experiment on site,the integrity of the test platform function and the feasibility and rationality of fault warning function are verified. |
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