Strain Transfer Theory And Sensing Property Research Of Strain Sensor

Strain (or stress) is a critical parameter that reflects the state of structure in scientific experimental research or the project health monitoring. Therefore, it is extremely important to select an appropriate and reliable strain sensor to measure accurately. As a front end of experimental research or monitoring system, the stability and reliability of the strain sensor affect the success or failure of the experiment or stability and reliability of the monitoring system directly.In order to analysis the strain transmission characteristics and the sensing properties of sensors with different measurement principles and packing ways, theoretical analysis method, finite element method and experimental method are applied in this article, and then the reliability of strain measurement is qualitative evaluated according to averaged strain transfer ratios and sensing properties of different sensors. The main research contents and results are as follows:1. The strain transfer ratio formula of strain sensor is derived with the analysis on strain transfer of different packing way ones. The influence rule of strain transfer ratio by several major parameters is obtained based on averaged strain transfer ratio formula.2. Finite element analysis models is built through finite analysis soft of ANSYS,which contains three surface type sensors with resistance strain gauge, metal substrate FBG and clamping type FBG and three submerged sensors with steel capillary encapsulating, monolayer embedded encapsulating and tube-encapsulated with end cap. The averaged strain transfer ratio formula and influence rule of strain transfer ratio by each parameter are verified through the finite element models.3. The MTS material testing machine is used on the tensile tests of resistance strain gauge, vibrating string strain gauge, patch type FBG strain sensor, clamping type FBG strain sensor and MTS extensometer. The performance index of linearity, repeatability, hysteresis and fatigue reliability of each sensor is obtained according to the tests.4. An observation is taken into the performances of prestressed RC beam model test and FBG smart strand relaxation test, and linearity of RC resistance strain gauges, submerged and surface type vibrating string strain gauge, submerged FBG strain gauge, mechanical dial strain gauge and FBG smart strand are measured.5. An summary and comparison on the sensing property and service property of the strain sensors are made to qualitative evaluate the advantages and disadvantages and the reliability of measurement.