疲劳损伤过程金属表面偏振热像纹理特征实验研究

Texture Characteristics of Polarized Thermal Images on Metal Surfaces in Fatigue Damage Process

红外热像法是检测金属疲劳损伤状况有效的方法,但是忽略了疲劳损伤过程中表面显微结构对自发辐射的影响,难以从微观角度对红外热像特征进行完整解释。金属疲劳是一个复杂的能量耗散过程,自发辐射具有偏振特性。在红外热像法中引入偏振探测,不仅能够获取温度场信息,而且能够获得包含发射率变化的表面纹理信息。基于此,搭建拉伸疲劳实验平台和偏振热像采集平台,以Q235低碳钢材料为研究对象,获取循环载荷作用下金属材料表面的热红外偏振图像,利用灰度共生矩阵(GLCM)提取偏振方位角、偏振度以及斯托克斯(Stokes)参量等热像纹理信息,分析金属疲劳损伤过程中金属材料的表面形貌的演化过程。实验结果表明,金属构件偏振热像纹理特征随着疲劳损伤周次不断变化,共生矩阵统计量呈现一定规律性。

Infrared thermography is an effective method for the detection of metal fatigue damage conditions.However, it does not consider the effect of surface microstructure on spontaneous emission in the fatigue damage process;thus, interpreting the infrared thermal image characteristics from a microcosmic perspective is difficult.Metal fatigue is a complex energy dissipation process, and spontaneous emission has polarization properties. By incorporating polarization detection into infrared thermography, besides temperature field information, surface texture information including emissivity change can also be obtained. Based on the foregoing, this paper obtained the thermal infrared polarization images of the metal material surface under cyclic load using Q235 low carbon steel as the research object by constructing a tensile fatigue test platform and a polarization thermal image acquisition platform. We investigated the evolution processes of surface morphology of metal materials during metal fatigue damage by using the gray level co-occurrence matrix(GLCM) to extract the thermal image texture information, such as polarization azimuth, polarization degree, and Stokes parameters. The results of the experiments show that the texture features of polarized thermal images of metal components change with fatigue damage cycles, and the cooccurrence matrix statistics exhibit some regularity with cycles.