布拉格光纤光栅光谱方法测量简支梁的垂向小位移

Fiber Bragg Grating Used as a Minute Displacement Sensor for the Displacement of a Cross Girder

分析简支梁的变形特点和FBG的衍射原理,提出通过FBG布拉格波长漂移量测量简支梁的垂向小位移的方法.理论分析了传感原理,并在不同的变形位移条件下测量了FBG中心反射波长的漂移量,验证了理论推导的正确性.理论推导和试验数据均表明,该方法的测量精度与FBG的有效折射率、空间周期和梁的厚度成正比;与梁跨度的二次方成反比;量程则相反.

Characteristics of cross girder distortion and the Bragg wavelength shift of fiber Bragg grating (FBG) are analyzed. A method for measuring minute vertical displacements in cross girders is proposed. The principles in sensing is deduced theoretically. The shift of central Bragg wavelength is measured under different conditions of distortion displacement. The experiment accords well with theoretical deductions in this analysis. The precision of measurement is in direct proportion to the effective index and spatial period of the FBG, and also the thickness of the girder,but in inverse proportion to the square of span of the girder. The scope of measurement has relationships in the contrary direction.