基于激光红外检测信号的表面裂纹定量重构

激光红外检测方法作为一种新型的远距离无损检测技术,对于表面裂纹的检测具有很高的效率.本文基于频域叠加法和数据库策略实现了激光激励下表面温度的快速数值模拟,研究了裂纹尺寸与温度分布间的关系,在时域与空域验证了快速数值方法的有效性.为基于红外检测信号实现裂纹尺寸的定量重构,选取合适的特征量并且建立了基于确定论方法的裂纹重构算法.最后,搭建了红外检测实验系统,进行了平板试件裂纹红外检测实验,基于实验信号实现了裂纹的定量重构,验证了重构算法的有效性.

Reconstruction of Surface Cracks with Laser Spot Thermography Signals

Laser spot thermography(LST)is a novel remote nondestructive testing technology.It can efficiently detect surface cracks.In this paper,a fast simulation method based on frequency domain summation and database strategy is developed to simulate the heat flow generated by the laser spot source and to investigate the relationship between crack size and temperature distribution.First,the feasibility of the new method is validated through comparison with a conventional method for both the time and the spatial domains.Second,suitable characteristic parameters are introduced,and a reconstruction algorithm based on a deterministic inversion method is developed.Finally,an infrared thermography testing system is established,and LST signals of surface cracks in a plate specimen are measured.The feasibility of the inversion method is validated by the accurate reconstruction result of crack size.