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本发明公开了一种基于光纤布拉格光栅传感器的局部裂纹实时监测方法,属于结构健康监测技术领域。裂纹尖端的应变分布具有明显的不均匀特性,当光纤布拉格光栅传感器在其栅点长度方向上受到非均匀应变时,反射光谱的形状与位置会发生变化。且应变梯度不同,其光谱变化程度不同。将结构待监测部位简化,并进行有限元分析得到不同裂纹长度下的应变分布,据此确定传感器的布局,提取反射光谱变化的特征参量,建立其与裂纹长度的定量关系,从而实现在有限长度范围内裂纹的实时监测。沿裂纹扩展方向布置若干传感器,使相邻传感器之间的距离小于等于后一传感器的有效检测范围,即可实现对任意规定长度的裂纹的实时监测。
The invention discloses a local crack real-time monitoring method based on a fiber Bragg grating sensor and belongs to the technical field of structural health monitoring. The strain distribution of the crack tip has obvious nonuniformity. When the fiber Bragg grating sensor is non-uniformly strained in the direction of the gate length, the shape and position of the reflection spectrum will change. And the strain gradient is different, the degree of spectral changes are different. The structure to be monitored is simplified, and finite element analysis is performed to obtain the strain distribution under different crack lengths. Based on this, the sensor layout is determined and the characteristic parameters of the reflected spectrum change are extracted to establish the quantitative relationship between the crack length and the finite length Real-time monitoring of cracks in the area. A number of sensors are arranged along the crack propagation direction, so that the distance between adjacent sensors is less than or equal to the effective detection range of the latter sensor, so as to realize the real-time monitoring of cracks of any specified length.