Temperature self-compensating type fiber grating strain transducer

Abstract

The invention relates to a temperature self-compensating type fiber grating strain transducer which comprises a first solenoid, a second solenoid, a metal tube, an elastic rod, fiber gratings, an outer tube and a mounting base, wherein two nuts are arranged on the solenoids; the first solenoid is in threaded connection with the left end of the metal tube; the left end of the elastic rod is connected with the right end of the metal tube to be extended into the metal tube; the right end of the elastic rod is connected with the second solenoid; the fiber gratings are welded at two ends of the elastic rod; the outer tube is sleeved on the exterior of the metal tube; and the mounting base is fixedly connected with a detected substrate. In the temperature self-compensating type fiber grating strain transducer, under a stress-free condition, a wavelength value does not change with the change of temperature, thereby achieving a temperature self-compensating effect. The change in stress of the detected substrate is directly reflected by a change data of wavelength of one fiber grating. The bottom of the base is welded with the surface of a reinforcing steel bar, thereby testing the change in stresses on the surfaces of concrete, reinforcing steel bar and steel structure and achieving monitoring and preventing functions. The silicone oil filled in the transducer can prevent interior parts from being oxidized or corroded after air enters.

Description

technical field [0001] The invention relates to the sensing field of optical fiber grating technology, in particular to a temperature self-compensating optical fiber grating strain sensor. Background technique [0002] The design principle of the fiber grating strain sensor is that the wavelength value of the fiber grating is linearly related to the stress under the action of stress. However, the fiber grating also has a heat-sensitive effect, that is, the wavelength value also changes correspondingly under the change of temperature, and the measured substrate also has a temperature effect (thermal expansion and contraction), so in the test environment with temperature difference, it must be Perform temperature compensation. Traditional fiber grating strain sensors, such as a fiber grating strain sensor disclosed in Chinese utility model CN2651704Y on October 27, 2004, generally use a temperature sensor connected in series next to the strain sensor to compensate for the tem...

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Problems solved by technology

[0019] The disadvantage of method 1 is that the temperature sensor needs to be kept in the same temperature environment as the substrate and the strain sensor to achieve accurate compensation. There is a difference in the temperature sensing speed between the temperature sensor and the strain sensor, which is difficult to do in an environment with large temperature fluctuations. To achieve accurate compensation, the thermal expansion and contraction of the matrix is ​​also used as a strain to participate in the stress calculation. When ΔT is large, a large strain value will be reflected, which is prone to false alarms. At the same time, it is difficult to calculate the actual stress of the matrix The second method has the following disadvantages: the value of the constraint condition A is difficult to measure, and the calculation error is relatively large. The expansion coefficient α is generally an empirical value, and there is a certain error. The entire compensation method is also relatively cumbersome. If it is health monitoring The writing of the system and software part is also more complicated

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