Performance of intelligent CFRP tendon based on long gauge FBG sensing technology
Fiber Bragg grating(FBG)sensing technology,due to its excellent performance,including anti-interference,integration of sensing and transmission,has become one of the key research directions for intelligent monitoring of Carbon Fiber Reinforced Polymer(CFRP)cable.However,traditional CFRP cables intelligent monitoring is spot or partial sensing,which is difficult to meet the needs for larger monitoring distance and range.Therefore,this paper proposed to combine long gauge FBG sensing technology with spiral tilt technology to develop an intelligent CFRP tendon.Through cyclic static tensile low cycle fatigue(under high stress conditions)and ultimate static tensile tests,this study explored the intelligent CFRP tendon performance of mechanical sensing and after the test under various tests conditions.The tests can show that the strain sensing performance of the intelligent CFRP tendon under different working conditions(15 kN,42 kN)has the linear correlation coefficient greater than 0.99 in three cyclic tensile tests,indicating good strain sensing performance and repeatability of the intelligent CFRP tendon.By comparing the FBG monitoring values with the strain gauge monitoring values,good consistency is demonstrated.During the low cycle fatigue tests,the FBG monitoring values are similar to the fatigue load change rule,and the error between the FBG monitoring values and the theoretical strain upper and lower limits is less than 8%.No anomalies are observed during the tests,such as data anomalies or strain perception lag.The survival rate of FBG is 100%,verifying the good strain sensing performance of the intelligent CFRP tendon,which can effectively monitor the axial dynamic strain.In the ultimate static tensile tests,the maximum wavelength changes of FBG reached 13 454 pm,and the monitoring values can exceed 11 000 μɛ,indicating that the intelligent CFRP tendon can monitor larger strain range.After three cyclic tensile and low cycle fatigue tests,the linear correlation coefficient of the FBG monitoring value of the intelligent CFRP tendon is better compared to the control group specimens,the ultimate load of the intelligent CFRP tendon decreased.The FBG strain monitoring range is almost unaffected.The early tests mainly caused cumulative damage to the material properties of the intelligent CFRP tendon.The test results can provide an important basis for the theoretical design and research of CFRP cable intelligent monitoring.
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