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脉冲热像法作为红外热像检测中具有定量分析能力的方法,其主要检测模型温差函数法在薄壁试件的缺陷深度检测时存在失效问题.为找出建模过程中的缺陷,以理想脉冲激励下一维有限形式的解析解替代原温差函数模型中的近似解,在温差曲线和温差导数曲线中,对模型中的核心参数峰值温差时间和峰值斜率时间的使用特性进行了比较分析.结果显示:峰值温差时间由参考点决定,而不由测试点决定,峰值温差时间不具备对缺陷深度的定量检测能力;峰值斜率时间的适用范围受到测试点与参考点实际深度之比的限制,根据给出的适用性判据公式求得该比值的上限在0.5附近,判据公式可作为使用峰值斜率时间的理论依据.
As a method of quantitative analysis in infrared thermal image detection, pulsed thermography has the main problem of failure detection when the model temperature difference function method is used to detect the defect depth of thin-walled specimens.In order to find the defects in the modeling process, By using the one-dimensional finite form analytical solution under pulse excitation, the approximate solution of the original temperature difference function model is replaced. In the temperature difference curve and the temperature difference derivative curve, the characteristics of peak temperature difference time and peak slope time in the model are compared and analyzed. The results show that the peak temperature difference time is decided by the reference point, not by the test point, and the peak temperature difference time does not have the quantitative detection ability to the defect depth. The application range of the peak slope time is limited by the ratio of the actual depth of the test point to the reference point. The formula of applicability criterion is given and the upper bound of this ratio is around 0.5. The criterion formula can be used as the theoretical basis for using peak slope time.