基于热成像的材料热扩散率测量方法研究

Research on Measurement Method of Thermal Diffusivity of Materials Based on Thermography

将一种基于热成像的薄片材料热扩散率测量方法的理论模型由二维拓展到三维,以适用于更大厚度材料的热扩散率测量。指出该方法适用的特征条件为:Z向空间导数值与材料表面和周围环境的温度差值为线性关系。仿真分析了传热距离与激励时间对特征条件的影响以及相关的信噪比问题,并在304不锈钢材料实测实验中依照仿真分析设置传热距离和激励时间以满足特征条件,结果显示厚度为1 mm和2mm的不锈钢材料测量偏差均在3.0%以内,厚度为5 mm的不锈钢材料测量的偏差为4.1%,从而扩大了该测量方法的适用范围。

The thermal diffusivity measurement method of the thin specimens based on thermography technology is researched and improved, and the theoretical model is developed from two-dimensional model to three-dimensional model, so that the materials with bigger thickness can be measured by this method. The characteristic condition, which must be satisfied when this measurement method can be used, is that the relationship between the spatial derivatives of temperature in Z-direction and temperature difference between the surface temperature of material and environmental temperature is a linear relation. The effects of conducting distance and excitation time on the characteristic condition are analyzed, and the relevant problems of signal to noise ratio by the simulation experiment are also studied. Setting the conducting distance and excitation time according to the simulation analysis when measure the thermal diffusivity of 304 stainless steel, the results show that the deviation of the measurement for the stainless steel with thickness of I mm and 2 mm is less than 3.0%, and the deviation of the measurement for the stainless steel with thickness of 5 ram is 4. 1%, so the range of application of the measuring method is expand,