基于红外热像偏振观测的金属疲劳表面显微结构演化与损伤评估方法研究

Metallic materials have been widely used in the fields of architecture, bridge, large mechanical equipment and so on. It is of great scientific significance to study the fatigue process of Ferromagnetic metallic materials. Quantitative infrared thermography can quickly detect the performance of metal fatigue, while it cannot give an explicit description, for the main reason is that the interaction mechanism between the surface microstructure and infrared thermal radiation has not been established. Therefore, to make clear the characteristic of the surface microstructure in the process of fatigue is the scientific problem that needs to be solved urgently in the development of the infrared thermal imaging detection technology. The project is aimed to investigate the mechanism of surface microstructure evolution and the relation model between thermal polarization characteristics and surface microstructure, as well as the thermal polarization characteristics of rough surface in fatigue damage process, and to solve the scientific problems of quantitative relationship between surface microstructure and thermal radiation and that between surface microstructure and fatigue damage, which will provide theoretical support for effectively quantitative assessment to detect metal fatigue damage using infrared thermography.

金属材料在建筑、桥梁、大型机械装备等方面有着广泛的应用，研究其疲劳过程具有重要的科学意义。定量红外热像法能够快速检测金属疲劳性能，但还不能给出精确描述，主要是由于没有建立表面显微结构与红外热辐射之间的作用机制。因此，明确疲劳过程中金属表面显微结构与热辐射特性是红外热像探测技术发展亟需解决的科学问题。本项目通过探索表面显微结构的演化机理，建立热像偏振特征与表面显微结构的关系模型，研究疲劳损伤过程粗糙表面热偏振特性，解决表面显微结构与热辐射、表面显微结构演化与疲劳损伤间的定量关系等科学问题，为疲劳损伤的定量化评估提供新的方法和理论支撑。

本项目研究了金属构件表面粗糙度、纹理特征在疲劳损伤过程中的演化规律，探索了表面形貌与疲劳损伤状况之间存在的关联性；基于微面元模型，提出了一种改进的六参量pBRDF模型，研究了金属粗糙表面反射偏振特性与自发辐射传输；利用热力学熵表征低周疲劳损伤程度，分析了加载幅值与加载频率的影响，建立了基于热力学熵的疲劳寿命预测模型；针对传统单幅图像分割算法不足，提出了基于Tsallis熵的红外偏振热像分割算法；通过低周疲劳实验，分析了金属疲劳过程红外偏振热像特征，给出了一种基于表面红外偏振热像特征的金属疲劳损伤评估方法。