基于激光散斑数字图像相关法的热应变测量

为了解决常规数字图像相关法应用于高温工况下热应变测量时，人工制作的散斑受高热载荷冲击容易出现变色、熔化、脱落的问题，采用激光散斑作为数字图像相关法特征纹理的方法，计算温度变化前后散斑图像相关性来测量金属热应变，进行了非真空环境下加热试件的实验，以及在管式加热炉中分别对铝试件和钨试件进行人工散斑和激光散斑的真空加热实验对比，取得了相应的散斑图像，并计算出平均应变曲线数据。结果表明，在非真空环境下，由于热流扰动导致激光散斑图像抖动较大，测量出的热应变曲线存在较大的干扰噪声；铝从室温升至450℃和钨从室温升至800℃的热应变与人工散斑结果相对一致；激光散斑数字图像相关法在类似聚变堆偏滤器高真空、高热流条件下，可以有效地测出金属壁面的动态热应变。该研究为聚变堆偏滤器第一壁材料的损伤诊断提供了新思路。

Thermal strain measurement based on laser speckle digital image correlation method

In order to solve the problem of discoloration, melting and falling off of artificial speckles when the conventional digital image correlation method is applied to thermal strain measurement under high temperature conditions, the laser speckle was used as the characteristic texture method of the digital image correlation method. The correlation of speckle images before and after temperature change to measure metal thermal strain was calculated, experiments of heating specimens in a non-vacuum environment were carried out, the artificial speckle and laser tests on aluminum and tungsten specimens in a tubular heating furnace respectively vacuum heating experimental comparison of speckle were conducted.The corresponding speckle images were obtained and the mean strain curve data were calculated. The results show that in the non-vacuum environment, the laser speckle image jitters greatly due to the disturbance of heat flow, and the measured thermal strain curve has large interference noise. The thermal strain of aluminum with the temperature increases from room temperature to 450 ℃ and the thermal strain of tungsten with the temperature increases from room temperature to 800 ℃ is respectively consistent with the artificial speckle results. This study shows that the laser speckle digital image correlation method can effectively measure the dynamic thermal strain of the metal wall under the conditions of high vacuum and high heat flow similar to the fusion reactor divertor, which provides a new idea for the damage diagnosis of the first wall material of the fusion reactor divertor.