Sensitivity calibration method of fiber Bragg grating strain sensor

The invention, which belongs to the measuring technology, relates to a sensitivity calibration method of a fiber Bragg grating strain sensor. In the invention, a four-point-bending equal-strength beam is used to calibrate a fiber Bragg grating strain sensor sensitivity. The method is characterized by: determining a position where the fiber Bragg grating is pasted on a standard beam; installing the standard beam on a fixed platform and using a standard beam fulcrum to support the standard beam on the platform; adjusting loading points of a loading beam so as to achieve uniform force on the standard beam; connecting the fiber Bragg grating sensor with a fiber Bragg grating demodulation device; applying a transverse force which is perpendicular to an axis on a midpoint of the loading beam, wherein an effect direction of the transverse force is superposed with a longitudinal symmetrical plane of the standard beam; applying load on the standard beam; using the fiber Bragg grating demodulation device to record wavelength change of the fiber Bragg grating; then calculating the strain of a beam surface and a sensitivity coefficient of the fiber Bragg grating so as to realize calibration. By using the method of the invention, uniform loading can be achieved; the uniform and stable force of the fiber Bragg grating can be guaranteed; a reliable parameter can be provided for technology research and measurement of the fiber Bragg grating sensor.