共查询到18条相似文献,搜索用时 218 毫秒
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涡流脉冲热像技术中,对含裂纹被测试件施加短时高频电流激励,裂纹面因涡流积聚会产生瞬时热量,进而由热传导引起试件表面温度分布的变化。为了分析裂纹传热特性,建立了涡流分布模型和简化传热模型,探索了试件表面温度分布的特点。制作了一系列含不同长度的贯穿疲劳裂纹金属试件,深入研究了裂纹区域热响应和裂纹长度之间的关系。数值模拟和实验结果表明:在特定的检测条件下,裂纹区域热响应与裂纹长度接近线性关系,满足正相关性,从而证明了简化传热模型的正确性。研究成果丰富了涡流脉冲热像技术的传热理论,为该技术的工程实践奠定了理论基础。 相似文献
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针对再制造工程中常见的喷涂层界面结合性能评价问题,采用脉冲红外热像技术对3Cr13合金涂层的界面脱粘缺陷进行检测评估。以信噪比(SNR)为评价标准,对比了两种不同热图序列处理方法在预处理和后处理阶段的效果。结果表明:在预处理阶段,基于表面热信号的多项式拟合算法(PF)将原始热图的信噪比由5.34提升到9.61,其效果优于基于单张图像中值滤波算法(MF);而在后处理阶段,基于单张图像的主成分分析法(PCA)对缺陷特征的表征比基于表面热信号的脉冲相位法(PPT)更加准确,第三主成分重建热图的信噪比达到17.99。综合而言,基于单张图像的热图序列处理方法在再制造喷涂层界面结合性能评价中具有更好的效果。 相似文献
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This paper reports on the use of eddy current pulsed thermography (ECPT) for detection and characterization of rolling contact fatigue (RCF). Detection mechanisms with eddy currents and heat propagation effects were discussed with RCF modeled as a simple angled defect. Two different angled defects were studied through numerical simulations and experimentally by using uniform magnetic field (UMF) excited by Helmholtz coils. Finally, a rail sample with RCF defects was inspected using UMF excitation. It is shown that ECPT with UMF excitation provides an efficient and robust method to detect angled defects, compared with nonuniform magnetic field (NUMF) excitation. 相似文献
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研究了应用超声红外技术检测复合材料试件冲击损伤缺陷。针对红外图像对比度差、缺陷轮廓模糊等特点,采用具有非高斯核函数的LBF模型进行了缺陷的边缘检测,利用缺陷边缘实现了缺陷的定量分析。从试验结果可以看出,LBF模型相对于其它常用的边缘检测方法,能够很好地检测低对比度红外图像的目标边缘,为复合材料缺陷的定量分析奠定了基础。从缺陷的长度和宽度定量计算精度可见,超声红外检测方法对于复合材料的缺陷是一种有效的检测手段,为复合材料的研制提供了强有力的技术支持。 相似文献
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This paper explores the feasibility of eddy current pulsed thermography (ECPT) to detect hidden cracks on corroded metal surface without removing the corrosion layer. The detection mechanisms are analyzed by using electromagnetic and heat conduction theories. Experiments are conducted on a metallic bar with three hidden cracks and the validity of ECPT is verified with the analysis of IR images and thermal responses. In order to further improve the detection sensitivity of ECPT, the principal component analysis (PCA) is applied to enhance the features of hidden cracks in the raw IR images by eliminating the effects of uneven corrosion and non-uniform heating. It is found that ECPT combined with PCA provides a convenient and effective way to detect hidden cracks on corroded metal surface. 相似文献
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航空发动机封严涂层质量检测仍然没有有效的无损检测手段,目前还是采用外观检查及破坏性检测方法完成。针对航空发动机封严涂层无损检测需求,开展脉冲红外热成像技术研究,采用闪光灯激励,实现对试件表面热激励,通过热像仪采集图像数据;为了提高图像的分辨率,采用1阶导(1-D)进行图像处理。在完成对人工制作厚度为1 mm的封严涂层试件实验检测后,发现该方法能够有效检测出试件中的2个缺陷,并可有效提取出缺陷大小信息,与实际缺陷大小基本一致,验证了脉冲红外热成像技术对封严涂层检测的有效性。 相似文献
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简要介绍了超声热成像检测方法的基本原理和特点。该方法利用激励超声波在缺陷处产生机械振动,使缺陷处因热弹效应和滞后效应等原因释放出热量,用红外热像仪对此局部发热过程进行监测,最后对图像进行分析。由于激励信号的频率调制和特殊的图像处理方法,超声热成像检测法优势独特。对某航空碳纤维增强复合材料的检测表明,该方法能有效检测出裂纹、分层或破裂等缺陷,应用前景广阔。 相似文献
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Infrared (IR) thermography is a two-dimensional, non-contact technique which can be usefully employed in non-destructive evaluation of materials. Basically, two different approaches are possible: traditional pulse thermography (PT) and modulated (or lock-in) thermography (MT). The attention of the present work is focused on the peculiar aspects, which characterise the two different techniques. Tests are carried out by considering glass–epoxy specimens and the results obtained, by employing either PT or MT, are compared. The capability of each technique, to detect a defect and give precise information about size, depth and thermal resistance of the defect, is analysed. The advantages and disadvantages of using these techniques are discussed in order to assess the fundamental requirements for the most appropriate choice in quality control processes. 相似文献