基于有限元的焊缝缺陷红外热像检测研究

Infrared Thermal Imaging Detection of Weld Defects Based on Finite Element Method

研究用红外热成像法分析和评价焊缝材料内部缺陷的可能性。利用ANSYS Workbench建立金属焊缝气孔缺陷的红外热像检测瞬态热分析有限元模型,通过分别施加脉冲激励热载荷、不同频率的周期热载荷,模拟脉冲热成像和锁相热成像两种方法用的热源。针对焊缝缺陷深度评估精度,将脉冲热成像与锁相热成像两种方法进行对比研究。记录缺陷表面的温度场响应,并采用傅立叶变换对仿真数据进行处理,求得不同深度缺陷的相位差,运用多项式拟合方法求得相位差与焊缝缺陷深度之间的定量关系。从结果总结出不同深度范围内焊缝缺陷检测的热源激励方式以及频率参数的选取,达到了较为满意的预测精度,为工程检测中焊缝缺陷热像检测的参数优化提供了参考,减少了参数重复设置而导致的时间浪费。

The possibilities of analyzing and evaluating the internal defects of weld materials using infrared thermal imaging were investigated.The finite element model for transient thermal analysis of metal weld defects by infrared thermal imaging was established by using ANSYS Workbench.The pulse excited heat load and periodic heat load with different frequencies were used to simulate the heat source of pulsed thermography and lock-in thermography respectively.A comparative study of the valuation precision of weld defect depth between pulsed thermography (PT) and lock-in thermography (LIT) was carried out.The temperature field response of the defect surface was recorded, then Fourier transform was used to process the simulated data and the phase difference corresponding to defect with different depth was calculated.The phase difference was correlated with the defect depth by Polynomial fitting method.The selection of heat source excitation mode and frequency parameters for weld defects detection in different depths was summarized to achieve satisfactory prediction accuracy, which provides a reference for parameter optimization of thermal imaging detection of weld defect in engineering and reduces time wastage caused by repeated parameter settings.