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利用在三维针刺C/SiC复合材料板上设计不同直径和深度的盲孔作为试样,模拟材料表面下的孔洞缺陷。采用红外热成像技术对试样盲孔缺陷进行检测,获得盲孔缺陷信息,通过最大温差法和lnT-lnt曲线二阶导数最大值法两种分析方法测量盲孔的深度并分析所产生的误差。结果表明:两种方法都可以实现对盲孔缺陷深度的定量测量,但产生的测量误差存在差异;当径深比为1～4.4时,采用最大温差法的误差明显小于lnT-lnt曲线二阶导数最大值法,而lnT-lnt曲线二阶导数最大值法的测量精度虽然稍低,但该方法所适用的径深比范围较宽,并且测量误差随着盲孔径深比的增大而减小。
A blind hole with different diameters and depths was designed on the three-dimensional acupuncture C / SiC composite plate to simulate the hole defects under the surface of the material. Blind hole defects were detected by infrared thermography, blind hole defect information was obtained. The maximum temperature difference method and the second derivative maximum value method of lnT-lnt curve were used to measure the depth of the blind hole and analyze the error . The results show that both methods can achieve the quantitative measurement of the depth of blind hole defects, but the measurement errors are different. When the aspect ratio is 1 ~ 4.4, the error of the maximum temperature difference method is obviously less than the second order of lnT-lnt curve Although the measurement accuracy of the second derivative maximum value method of lnT-lnt curve is slightly lower, the range of depth-to-diameter ratio applicable to this method is wider and the measurement error decreases with the increase of the ratio of the depth of blind hole small.