光纤布拉格光栅(FBG)应变测量是基于光栅受到轴向应变作用时其波长将会发生相应变化。但在复杂应力状态下,由于横向效应的存在,光纤布拉格光栅的安装方位对光纤应变测量产生影响。通过理论推导和实验分析验证了安装方位对光纤应变测量的影响,并以单向应力状态为例,导出应变测量误差与光纤布拉格光栅安装方位的关系曲线：光纤的轴向与主应力的夹角60°附近,误差急剧增大,可使测量结果严重失真。为消除安装方位引起的误差,给出了复杂应力状态的应变测量修正公式。

The strain measurement by the fiber Bragg grating (FBG) is achieved by the change of FBG′s wavelength upon axial strain. But in the complicated stress state, the FBG′s strain respond error occurs due to the transverse effect. The impact of direction of FBG on strain measurement is proved through theoretical analysis and experimental results. The relationship between direction of FBG and strain measurement error in the state of uniaxial stress was derived and tested. The results indicate that the error increases rapidly when the FBG angle is about 60°, the results of strain are distorted extremely. In order to remove the error, modified formulas for strain were derived.