Study On Strain Transfer Mechanism And Temperature Compensation Of Surface Pasting Substrate FBG Sensor

Port machinery,aircraft engines and heavy-duty CNC machine tools and other large machinery equipments,are not only the key equipment for stable development of national economy,but also are the strategic core equipment that affects the national security and decides the level of national defense construction.By using strain measurement technology to monitor these large machinery equipments,we can grasp the running state of mechanical systems in real time.However,because of its poor ability of anti electromagnetic interference and stability,it is difficult to adapt to structure and working environment of these large machinery equipments for traditional strain measuring instruments.At the same time,they are also not convenient for multipoint dynamic distributed measurement.Compared with these traditional electric sensors,FBG is a new type of passive sensor with the advantages of small size,high sensitivity,low loss,good insulation,anti electromagnetic interference,easy multipoint arrangement and so on.It provides a new research direction for on-line monitoring of large mechanical equipment.This paper is supported by National Natural Science Foundation of China.In the background of on-line monitoring of large mechanical equipment,this paper focuses on that the detection strain of FBG is different from the actual strain of structure and FBG has a cross sensitivity of temperature and strain in the strain measurement process of FBG sensor.In this paper,strain transfer mechanism and temperature compensation method of substrate type FBG sensor attached on the surface are studied.The main work and research results are as follows.1.In strain measurement process of FBG sensor,the detection strain of FBG is different from the actual strain of structure.This paper established a five-layer structure model contains matrix structure,bottom,paste layer,substrate,paste layer and fiber.The strain transfer model of substrate type FBG sensor attached on the surface is deduced,and the influence of sensor on structure is calculated.The effect of sensor parameters on transfer efficiency is studied.The packaging and pasting parameters of substrate type FBG sensor attached on the surface are summarized.An corresponding finite element model is established to simulate and analyze.2.In the pasting process of FBG sensor,preload exists the influence on the stability and repeatability of sensor strain measurement.The influence of the consistency and optimality of preload on the stability and repeatability of sensor strain measurement is studied through experiment.Then,two sets of FBG sensor paste tool and a set of FBG sensor package are designed.3.The temperature response model of substrate type FBG sensor will be changed in the practical application.The temperature response model of substrate type FBG sensor attached on the surface is derived and established.Then,an corresponding finite element model is established to simulate and analyze.4.In the strain measurement process of FBG sensor,FBG has a cross sensitivity of temperature and strain.The temperature change of the working environment has a great influence on the measurement results.This paper presents a design method of temperature compensation for substrate type FBG sensor by using double grating vertical sticking method.The strain and temperature sensing characteristics of sensor are studied by theoretical analysis and experiments.