基于改进遗传算法双重约束的FBG应变分布重构研究

光纤布拉格光栅(FBG)已广泛应用于应变参数测量中,但非均匀应变易引起FBG光谱变形而无法进行波长检测,因此需重构沿FBG的应变分布。针对应变分布重构效果差且收敛速度慢的难题,在深入研究改进遗传算法的基础上,提出基于FBG光谱中心波长位置与反射率双重约束的应变分布重构理论,显著改善了重构的非唯一性和置信度。同时,假设应变分布为多项式形式,通过对多项式系数的重构实现应变分布的重构,大大提高了重构的速度。在此基础上开展了应变分布参数重构仿真实验,多项式系数重构误差均小于1.5%;结合两端固定压杆调谐光纤光栅实验,验证了该应变分布重构方法的有效性、适用性和可操作性,形成了一种快速有效的应变分布重构方法。

Study of FBG Strain Distribution Reconstruction Based on Improved Genetic Algorithm Dual Constraint

Optical fiber Bragg grating (FBG) has been widely used to detect strain. Nevertheless, uneven strain is easy to cause deformation of FBG spectrum, which will result in the invalidation of wavelength detection. Therefore, it is necessary to reconstruct the strain along FBG. In response to that traditional strain distribution reconstruction theory both have poor effect and slow convergence speed, strain distribution reconstruction theory based on FBG central wavelength and reflectivity of spectrum dual constraint is presented after deep research on improved genetic algorithm, which significantly improves the non uniqueness and the confidence of reconstruction. At the same time, assuming distribution of strain is polynomial, reconstruction of strain distribution is realized through reconstructing the coefficients of the polynomial, which has improved the speed of strain distribution reconstruction. And then strain parameters reconstruction numerical simulation experiments are comprehensively carried out, and the errors of the reconstructing polynomial coefficients are all less than 1.5%. Through tuning FBG by two ends fixed compression bar experiment, the validity, applicability and practicability of the novel reconstructing method have been verified. Consequently, a novel method of reconstructing strain distribution which is fast and efficient has been generated.