Structural Optimization And Measurement And Control System Design Of Reciprocating Friction And Wear Tester Based On Flexible Beam

Friction and wear tester is a device used to evaluate the friction and wear properties of materials.It can explore the wear mechanism of specimens under variable load,variable speed and various temperatures,and obtain the friction coefficients under different working conditions.Advanced friction and wear tester is of great significance for the further development of tribological research.Most of the friction and wear testing machines on the market are in the form of end friction.The friction and wear testing machines for the cylindrical pairs with reciprocating motion have few types,low versatility and high price.Based on the above situation,a new type of reciprocating friction and wear tester is developed in this paper.The main work is as follows:1)According to the principle of friction coefficient measurement and the actual working conditions and functional requirements of the tester,the transmission system,loading system and friction conversion system of the tester are designed.2)Aiming at the vibration and harm caused by the test machine in operation,the mathematical model of the crank-slider mechanism with minimum fluctuation of reciprocating speed is established.The crank length,connecting rod length and offset are optimized by combining genetic algorithm and variable range optimization method,and its kinematics performance is verified.The whole virtual prototype of the testing machine is built,and the vibration of the machine under variable speed and load is explored by ADAMS,and the structure is optimized.Through the actual work,it can be seen that the vibration and shock of the test machine are obviously reduced after optimization.3)The measurement and control system of the whole testing machine is built.According to the method of transforming the deformation of flexible beam into electrical signal output by strain gauge,the frictional force signal acquisition and amplification system is designed.LabVIEW is used to build the login system,data acquisition system and data query system of the test machine.Combining wavelet packet denoising and arithmetic average method,the output signal of the acquisition card is processed,which improves the accuracy of measurement results.4)The designed testing machine is processed and debugged,and a testing machine platform integrating measurement and control is built.The test conditions of the tester,including test materials,environmental conditions,specimen preparation and test parameters,are given.Then,the voltage signals of flexible beams are calibrated by weights of 0N,5N,10 N,15N,20 N,25N,30 N and 35 N,and the first-order linear relationship between the voltage signals and the calibration force is obtained: f(x)= 0.002239 x + 0.02312.By changing the load and speed,the friction force and coefficient in different time periods are obtained,and the relationship curve is generated.The results show that the friction coefficient decreases with the increase of load and increases with the increase of speed.Fig [70] table [16] reference [77]...