基于锁相法的涂层缺陷检测识别的仿真研究

Simulation on detection and recognition of coating defect based on lock-in thermography

针对涂层脱粘缺陷不易检测识别的问题,建立了涂层脱粘缺陷的三维非稳态导热模型,对模型受热过程进行了仿真计算。在不同涂层厚度与加载频率下,沿缺陷半径方向均匀取点,提取涂层表面温度变化相位,并对相位变化曲线进行一阶差分。研究结果表明:锁相法对涂层缺陷具有很好的检测效果,涂层较厚时适合低频加载,涂层较薄时适合高频加载,在合适的加载频率下,通过相位一阶差分曲线可有效对缺陷进行定量识别。

As the debonding defect of coating isn , t easy to detect and recognize, the 3D unsteady heat conduction model of coating debonding defect was established and the heating process of coating defect model was calculated nu-merically. The points were selected along the defect radius direction, and the phases of temperature changes on coating surface were extracted under different coating thicknesses and loading frequencies, and then first order difference was carried out for phase changing curve. The result show that thicker coating is suitable for low frequency loading and thinner coating is suitable for high frequency loading, and coating defect could quantitatively be recognized under a suitable frequency after the first order difference of phase, so lock-in thermography has good detection effect for coating defect.