Study On Temperature And Strain Characteristic Of Distributed Sensing Optical Fiber Cables

In modern measurement techniques,Optical fiber sensing technology has attracted more and more attention because of its unparalleled advantages.And distributed optical fiber sensing technology has became critical focus area of domestic and foreign researchers,because it can realize the real-time monitor of long distance.This technology has been widely used in electric power,military,perimeter security and other fields.At present,a number of studies have already been done to improve the measurement accuracy from the system,but the cable also have some impact on the measurement accuracy in the actual measurement process.On this paper,we have studied the characteristics of senor cable of distributed optical fiber sensing system based on Brillouin scattering(BOTDA).The research is divided into two aspects:one is the temperature passing time of the temperature sensor cable;the other is strain transfer performance of strain transfer cable with different materials and layout methods.The details are as follows:Firstly,introduced the basic theory of heat transfer science,and analyze the temperature transfer mechanism of temperature sensing cable based on the heat transfer science.And modeling the cable to simulate the process of heat transfer in finite element software,design the temperature relay experiment to validate the result of simulation,providing a way to measure the temperature pass time of cable,and conduct experiments of cable and tightly packaged fiber with BOTDA, it shows that the cable will have an impact on the reponse time of BOTDA system.Then analyze strain transfer characteristics of the strain sensing cable in different layout methods: firstly analyzes the strain transfer principle of embedded fiber optic cable,modeling the strain transfer cable which has been buried in the structure matrix,analyze the factors that effect the performance of strain transfer.The results of simulation show that the smaller the thickness of the coating layer’s elastic modulus,the better the effect of strain transfer,by contrast,the jacket layer has less effect on the cable’s strain transfer,even it will be ingored; then analyze the transfer mechanism of srain sensing cable which has been pasted on the surface of structure matrix,the analysis about the mechanism is based on the thesis of FBG that located in the surface,at last,get the strain transfer coefficient expressions.Surface bonded methods are divided in twoways:fixed-point paste and comperehensive paste,and simulated these ways in the finite element software to get their strain transfer coefficient curves.The results of this paper will provide guidance for the choice of cable which used in different occasions,they also can help choose the best setting way of cabel.And the results is expected to facilitate further optimization of distributed optical fiber sensing system.