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利用脉冲红外热成像技术对碳纤维复合材料试件内部的模拟脱黏缺陷的深度进行测量,研究在被测物热属性参数未知情况下,碳纤维增强塑料中缺陷深度的测量方法.分析了平板材料在脉冲热源激励下的一维热传导模型;给出了内部缺陷深度的红外测量原理;选用对数温度二阶微分峰值时刻作为特征时间测量缺陷深度;考虑单点标定测量深度可能产生较大的随机误差,提出利用最小二乘法多项式拟合建立阶梯件中阶梯深度与其对应的对数温度时间二阶微分曲线峰值时间两者之间的标定关系式的方法,选择在相对误差平方和最小情形下的拟合关系式作为脱黏缺陷深度测量的标定关系式.实验结果表明,利用该方法测量脱黏缺陷深度的精度优于单点法标定测量结果,实现了在被检测材料热属性参数未知的情况下仍能较准确地测量脱黏缺陷深度.
The depth of simulated debonding defects in carbon fiber composite specimens was measured by pulsed infrared thermography, and the method of measuring the depth of defects in carbon fiber reinforced plastics under the condition of unknown thermal parameters was studied. One-dimensional heat conduction model under the pulse heat excitation is given. The infrared measurement principle of the internal defect depth is given. The second-order differential peak time of logarithmic temperature is selected as the feature time to measure the defect depth. Considering the single point calibration measurement depth, large random errors may occur , The least squares polynomial fitting method is proposed to establish the calibration relation between the step depth in the ladder and its corresponding second-order differential curve peak time in temperature. As the calibration relation of the depth measurement of the debonding defects.The experimental results show that the accuracy of the depth of the debonding defects measured by the method is better than that of the single point calibration method and realized that when the thermal property parameters of the tested materials are unknown Still can more accurately measure the depth of debonding defects.