Design And Research Of FBG Pressure Sensor Based On The Principle Of Mechanical Balance

Pressure is the main cause of structural deformation and damage,and pressure is considered as an important parameter for monitoring and safety assessment of engineering operation state.At present,the traditional pressure measuring device is difficult to meet the actual demand in precision,sensitivity,corrosion resistance,anti-interference ability and so on,so it has the limitation of measurement.Fiber Bragg grating has many advantages,such as small volume,light weight,strong anti-electromagnetic interference ability and good corrosion resistance,and is widely used as a sensing element.Based on the research of fiber Bragg pressure sensors at home and abroad,the basic working principles and advantages and disadvantages of several common sensing structures are summarized in this paper.On this basis,two kinds of FBG pressure sensors with different structures are developed by using the excellent properties of FBG and the principle of mechanical balance:arch FBG pressure sensor and lever FBG pressure sensor.After the theoretical optimization of the sensor structure and the improvement of the processing technology,the two pressure sensors have the advantages of simple structure,high force transmission efficiency,easy processing and low cost.The calibration tests of the two pressure sensors were carried out respectively.Among them,the best sensitivity of the arch FBG pressure sensor reached 0.232pm/N,the fitting degree was 0.9991 and the linearity was 1.421%.The optimal sensitivity of lever FBG pressure sensor is 3.833nm/MPa,7.980nm/MPa and 17.075nm/MPa when the fulcrum of the FBG pressure sensor is located at the right end,the middle and the left.The comparison shows that when the fulcrum is from right to left,the pressure sensitivity is continuously increasing while the loading pressure is decreasing.Experiments show that the sensitivity of these two structures of FBG pressure sensor has reached the leading level at present,the linearity is good,the working performance is stable and the durability is good,which indicates that the two kinds of structural forms are designed reasonably and can realize the long-term and stable monitor.The main contents of this article are as follows:1.Analyze and summarize the working principle of the existing pressure sensors at home and abroad,and compare the sensing performance and the main applicable scope;2.Explain the structure of FBG and the sensing principle of temperature,strain and pressure to provide the corresponding theoretical basis for the development of FBG pressure sensor;3.Based on the principle of self-balance system of arch-beam composite structure,an arch-type fiber grating pressure sensor is developed.The rational arch axis form of the three-hinged arch in the structure improves the pressure transmission efficiency and realizes the accurate pressure measurement.4.The FBG pressure sensor with diaphragm-lever combination structure is designed based on the principle of lever balance.The experiment shows that it is possible to adjust the sensor accuracy,sensitivity and range by adjusting the position of lever fulcrum.5.Under the same working condition and the same pressure,the sensing performances of the two structures are compared and analyzed.It is found that the sensitivity of the lever structure is better than that of the arch structure,but the linearity of the arch structure is relatively better.The above phenomenon was analyzed in detail,and some suggestions for improving the performance of the two sensors were put forward.