基于数字散斑技术的炭/炭复合材料高温应变测量

Strain measurement of carbon / carbon composites at high temperatures by digital speckle correlation method

主要介绍了炭/炭(C/C)复合材料在高温下(最高至2 600℃)利用数字散斑技术进行的应变测量。试样表面喷涂钨粉作为目标散斑。在试验环境箱中将试样升温至试验温度。在拉伸过程中,对C/C复合材料试样及喷涂其上的钨粉散斑进行窄带滤光,并对滤除炭纤维发出光线后的图像进行采集,对图像中的散斑点进行计算区域的选取,通过散斑点的位移来确定试样在散斑喷涂区域内材料的变形,进而得到在2 600℃温度条件下试样有效段的应变。测量结果表明,该方法可直观准确地反映出C/C复合材料试样在2 600℃应变状态,对于需要测量的关键点可实现重点跟踪,动态测量出该点在任意时刻任意位移的应变。该测试方法精度高,并可应用到不同受力方向的应变测试场合。

A method of strain measurement at high temperatures （ up to 2 600 ℃） for carbon/carbon composites by digital speckles was introduced. The samples in the test were sprayed with tungsten powder as the target speckles. Then the samples were heated to the test temperature. The samples emitted bright light by carbon/carbon composites and tungsten. After the narrowband fil-tered the light in the tension test, the light by carbon fiber was filtered and the light by tungsten was reserved. Then the image ac-quisition was performed. It is found that the image processing can reflect the strain state, reconstruct the profile of the specimen sur-faces vividly and reproduce the deformation field of the strain field. For critical points, the image processing can also track their trajectory and calculate their strain at any time and arbitrary displacement. It also shows that the digital speckle correlation method is an accuracy measurement. Furthermore the method can be utilized to various mechanical sites.