Research On Fatigue Force Sensor Based On Fiber Grating Sensing Technology

Fatigue force sensors are mainly used for force measurement,monitoring and control in laboratory testing,industry and process control.With the improvement of safety and reliability of products and equipment,higher requirements are put forward for the measurement environment,measurement accuracy and fatigue performance of fatigue force sensors.The traditional electrical fatigue force sensor is vulnerable to electromagnetic interference and its sensitive grid is prone to fatigue damage after a long time of operation.Based on the advantages of fiber grating,such as strong anti-interference ability,simple structure and good fatigue,a fatigue force sensor is developed in this paper using fiber grating as a sensing element.Based on optical fiber sensing technology,this paper takes 100kN force sensor as the research object,uses optical fiber grating instead of traditional sensing element resistance strain gauge,researches the strain transfer law of optical fiber based on Ansys Workbench simulation analysis software,optimizes the elastic body structure by combining static strength index and strain distribution,puts forward the optical fiber laying scheme to realize temperature compensation and enhance the sensor's ability to resist eccentric load,and finally verifies the sensor's technical index through prototype experiments.The main contents of this paper are as follows:(1)Through the load test,the measurement characteristics of the resistance strain gauge and the fiber grating,their anti-interference ability in the magnetic field environment and the wiring method of the two sensing elements are compared and analyzed,which all show the advantages of fiber grating as a measuring element.(2)Determine the package form of the fiber grating,establish a simple model,and study the factors affecting the matrix-fiber strain transmission rate through theoretical derivation and simulation analysis.From this,the spoke model is specifically used to verify the transfer law,and the reasons for the error between the transfer rate obtained by the spoke model and the simple model are analyzed.Finally,the bonding method of fiber grating and the key size of elastomer structure are determined based on the research results.(3)Based on the simulation analysis and orthogonal test,the structural design of the main dimensions of the spoke is carried out by combining the maximum equivalent stress and spoke strain,the optimal size combination scheme is found,and the strain transfer rate and fatigue life under this condition are verified.In order to realize temperature compensation and improve the anti-bias load capability of the sensor,the best fiber grating laying scheme is sought.(4)Static performance tests are carried out on the developed force sensor prototype,and its key performance indexes are calculated.Through comparison with relevant national standards,the product performance is verified to conform to the national standards.The stability and accuracy of the dynamic output of the force sensor under cyclic load are verified through the dynamic test of the force sensor prototype.