Structural Design And Experimental Study Of Force Sensors Based On Fatigue Performance

The force sensors are used to monitor stress state of the key component in machine which are widely used in manufacture.With the improvement of processing level and the quality requirements of parts,fatigue failure has gradually become one of the main failure modes of force cells.Therefore,design and optimization of sensors are based on the finite element calculation and experiment check to enhance the performance of static strength and fatigue life,as the same time to ensure the measuring accuracy and reliability.In this paper,Ansys Workbench and Ncode Designlife simulation software are used to analyze the performance indexes of static strength and fatigue strength.The elastic body of force cell is divided into the spoke main structure and the thread structure to simulate and do experimental verification.The structure of force cell with a range of 125 KN would satisfy the static strength and fatigue strength after optimum design.The best location of the strain gauges are obtained by the finite element analysis,and a double-channel full-bridge circuit and the peripheral conditioning circuit are set up to ensure the accuracy and reliability of strain measurement.The main work of this paper are as follows:(1)Through the simulation analysis and fatigue life calculation of the spoke main structure,the static strength and fatigue life would be changed with the length,width,height,transition fillet and inclination angle of spoke.Comprehensively considered strain gauge paste,the overall structure of the size,difficulty of processing and other factors,the final shape and size of spoke main structure would be determined which owns great fatigue performance.(2)Through the finite element simulation and fatigue life calculation of the thread structure group,the thread fillet radius,friction coefficient,the number of threads and the height and outside diameter of the hub would be optimized to determine shape and size of the thread structure.(3)Based on the finite element analysis,the stress concentration area on the side of the spokes is obtained which determines the location of the strain gauges.The full-bridge circuit of double-channel are used to ensure the accuracy and reliability of the strain measurement.The signals amplified and filtered by the external circuit are added to ensure output voltage to meet the requirements of force cells.(4)The elastomer specimen is processed to do the static and dynamic tests.The data of the two channels are fitted to obtain the correction coefficient and the linearity.The error values of the two channels were compared to ensure stability and reliability of the force sensor.(5)Through the comparison of experiment and simulation of the external thread fixture,the error coefficients of manufacture and assembly in the simulation of fatigue calculation are corrected.The fatigue life of the elastomer is estimated which would be compared with the experimental results of the elastomer then,to verify the reliability of the simulation calculation.