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脉冲红外热波检测是一种新兴的无损检测技术,通常采用反射型激励方式。针对反射法缺陷深度检测误差大的不足,系统分析了透射法的红外脉冲热波定量检测缺陷深度。通过分析材料在脉冲热激励下的一维热传导模型,探讨了缺陷深度的红外测量原理。利用表面温度一阶微分峰值时间法建立特征时间与缺陷深度的关系,实现对缺陷深度的定量检测。以PVC板人工楔形槽缺陷为例,采用透射法与反射法对比实验分析缺陷深度的测量误差。结果表明,反射法在对缺陷进行定量计算时需要选取参考区域,而透射法对数据的处理不依赖参考区域,避免参考区域所带来的误差。透射法直接加热缺陷面,响应时间短,通过求解缺陷处的特征时间计算缺陷深度,检测精度得到大幅度提高。
Pulsed infrared thermal wave detection is a new nondestructive testing technology, usually using reflective excitation. Aiming at the deficiency of large detection error of reflection defect, the depth of defect was quantitatively analyzed by infrared pulse heat wave transmission method. By analyzing the one-dimensional thermal conductivity model under the pulse thermal excitation, the infrared measurement principle of defect depth is discussed. The relationship between characteristic time and defect depth was established by first derivative differential surface time of surface temperature to realize the quantitative detection of defect depth. Taking the artificial wedge groove defect of PVC plate as an example, the measurement error of defect depth was analyzed by contrast experiment of transmission method and reflection method. The results show that the reflection method needs to select the reference area when calculating the defect quantitatively, while the transmission method does not rely on the reference area to process the data and avoids the error caused by the reference area. The transmission method directly heats the defect surface, and the response time is short. By calculating the characteristic time of the defect, the defect depth is calculated and the detection accuracy is greatly improved.