共查询到19条相似文献,搜索用时 698 毫秒
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利用有限元方法,对涡流检测中的电磁场问题进行数值计算,有助于涡流检测线圈的优化设计、检测缺陷的识别与定量,从而提高涡流检测的效果与精度。为验证有限元数值计算结果的有效性,对TEAM(Testing Electromagnetic Analysis Methods)组织提出的Workshop问题(Problem 15)进行了求解与分析。利用解析方法计算了空芯线圈的阻抗,然后通过二维有限元模型进行了阻抗求解,对比结果有较好的一致性。针对厚板上裂纹的涡流检测,建立了三维有限元计算模型,对影响计算结果的因素进行了分析,得到了比较好的数值模拟结果。 相似文献
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针对轧辊表面缺陷检测方法的选择,以及涡流检测原理和涡流检测时遇到的各种问题,着重分析涡流检测灵敏度设定以及轧辊材质对涡流探伤的影响,并利用其它检测方法来校验涡流的检测结果,对实际缺陷的当量、形状和缺陷的种类进行分析,完成轧辊的质量控制。 相似文献
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核电是公认的清洁能源,但核电安全问题日益引起人们的高度关注。采用有限元仿真的方法研究了核电站蒸汽发生器传热管缺陷特征与涡流阻抗信号之间的关系。利用内穿式差动Bobbin线圈对传热管缺陷进行了数值模拟检测。研究了缺陷形状结构对缺陷信号特征的影响,分析了检测频率、裂纹宽度和裂纹深度对缺陷信号特征的影响。通过对仿真试验结果的分析,发现不同缺陷结构、不同缺陷宽度、不同缺陷深度及不同检测频率对涡流阻抗信号影响具有各自明显的规律。该研究成果对核电站在役管道的涡流无损检测具有重要的实用价值和理论意义。 相似文献
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为了有效利用脉冲涡流信号的低频成分检测钢板内部裂纹缺陷,提出了脉冲涡流同步采样方法。介绍了该方法的工作原理;采用在钢板上加工不同规格矩形槽的方法模拟钢板的裂纹缺陷;设计了由激励线圈和检测线圈构成的传感器,实现脉冲涡流信号的提取;采用数据采集卡采集信号,以Labview为平台,实现同步采样方法的软件设计。对钢板缺陷的检测和试验数据的分析,证明了脉冲涡流同步采样方法在钢板内部裂纹缺陷检测中具有较高的灵敏度,可以有效识别钢板内部裂纹缺陷。 相似文献
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This paper describes a new scheme for the fast evaluation of eddy current testing (ECT) signals by using databases and formulation of the A−φ method. As the calculation of flaw signals is localized around the flaw region, substantial computational work can be reduced comparing with the conventional FEM–BEM code even for a conductor with complex geometry. Unlike the approach proposed by Badics et al. (Rapid flaw reconstruction scheme for 3-d inverse in eddy current NDE. In Studies in Applied Electromagnetics and Mechanics, Vol. 12, eds T. Takagi et al., IOS Press, 1997, pp. 303–309), the new scheme can predict ECT signals due to a large and complex-shaped crack rapidly because of its higher order interpolation and the newly introduced special element, say, an element with different media. The efficiency of the new method is verified by comparing its numerical results with the measured impedance for several bench-mark problems. The fast and accurate features make this new forward approach especially feasible in the reconstruction of flaw shapes by combining with the conventional optimization method. 相似文献
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针对单一神经网络在涡流无损检测中存在识别精度低、训练时间长和识别范围小的缺点,提出了一种适用于实时在线检测的神经网络结构——层次式多子网神经网络。该网络包括一个总网和各层子网,可以将一个复杂的任务分成多个小任务去完成,能快速识别出缺陷有无、走向以及大小。由于每个网络采用改进的径向基神经网络优化隐含节点数,利用小波多尺度边缘检测方法提取输入信号的特征值以简化输入节点数,网络结构得到极大简化。结果表明,层次式多子网神经网络适用于实时在线检测。 相似文献
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This study proposes the construction of the probability of detection (POD) as a function of both the depth and length of a flaw. In addition, this study discusses how to censor signals in constructing the POD. The general effects of the flaw parameters on signals are evaluated by numerical simulations, and the scattering of signals, which is critical to the POD, is estimated by signals obtained in experiments. A new likelihood function is introduced, and the proposed method is demonstrated using eddy current signals caused by various artificial flaws on a flat type 316L stainless steel plate obtained in a laboratory test. The demonstration confirms that the proposed method can provide a reasonable POD with a small amount of experimental signals, and reveals that proper censoring significantly decreases the detrimental effect of noise on the POD. 相似文献
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连续运动薄板横向磁通感应加热耦合场分析新方法 总被引:5,自引:1,他引:4
通过沿薄板运动反方向以单元格的形式平移薄板中的热源来取代薄板的连续运动,使得温度场的每次计算可以采用相同的热源分布,无需重新计算涡流场,大大减少了横向磁通感应加热耦合场数值仿真的时间。利用有限元数值计算结果作为神经网络的训练样本,分别建立了横向磁通感应加热装置出口处平均温度及其平均相对误差的预测模型。检验样本的结果表明所训练的神经网络具有很高的准确性。利用神经网络分析了频率和电流对平均温度及其平均相对误差的影响,并应用模拟退火法对频率和电流进行了优化以获得给定温度下的最小平均相对误差。 相似文献
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This paper proposes a generalization for the solutions of an inversion method developed by the authors. The method is based upon an artificial neural network that simulates mapping between eddy current signals and crack profiles. One of the biggest advantages of the approach is that it can deal with conductive cracks, which is necessary to reconstruct natural cracks. However, it has one significant disadvantage: the reliability of reconstructed profiles was unknown. This paper also proposes a novel parameter that provides an index for assessment of the crack profile and overcomes this disadvantage. After the parameter is validated by reconstruction of simulated cracks, it is applied to reconstruction of natural cracks that occurred in steam generator tubes of a pressurized water reactor. It is shown that the parameter is applicable to not only simulated cracks but also real (natural) ones. 相似文献