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粉末冶金导杆类产品缺陷的EMT有限元仿真

EMT Finite Element Simulation of Defects in Powder Metallurgy Guide Rod Products

  • 摘要: 本文利用有限元仿真分析方法,采用COMSOL Multiphysics仿真软件建立了粉末冶金导杆类零件中常见的缺口、夹杂缺陷模型,研究了激励频率、缺陷位置对电磁层析成像(electromagnetic tomography,EMT)系统接收线圈输出电压的影响规律;同时,利用LBP、Tikhonov正则化两种图像重建算法,重建了粉末冶金导杆类产品缺陷分布图像,并针对两种算法的成像精度进行对比分析。结果表明,EMT系统接收线圈输出电压值随着激励频率的增加而逐渐增加,且EMT系统激励频率与接收线圈输出电压的虚部值呈现更明显的线性关系,因此,选取线圈电压的虚部值表征接收线圈输出电压变化趋势更有优势。此外,被测零件中缺陷位置越靠近接收线圈或激励线圈,EMT系统输出电压的虚部值变化越明显;当激励频率为10 kHz时,更容易识别出粉末冶金导杆类零件中不同位置的缺陷。对比分析LBP和Tikhonov算法的成像质量,Tikhonov算法的重建效果较好,图像中缺口、夹杂缺陷更接近原始模型分布,因此,Tikhonov算法更适用于重建粉末冶金导杆类零件的缺陷图像。本研究旨在为提升EMT系统检测粉末冶金导杆类产品缺陷的准确性和缺陷成像质量提供参考依据。

     

    Abstract: In this study, finite element simulations were conducted using COMSOL Multiphysics software to model common defects, such as notches and inclusions, in powder metallurgy (PM) guide rod components. The effects of excitation frequency and defect location on the output voltage of the receiving coils in the electromagnetic tomography (EMT) system were systematically investigated. Furthermore, two image reconstruction algorithms, namely linear back projection (LBP) and Tikhonov regularization, were employed to reconstruct defect distribution images, and their imaging accuracy was comparatively analyzed. The results show that the output voltage of the receiving coils increases with excitation frequency, and a clear linear relationship was observed between the frequency and the imaginary part of the output voltage. Therefore, the imaginary part of the coil voltage is more suitable for characterizing the variation trend of the output voltage. In addition, the variation in the imaginary part of the output voltage becomes more significant when the defect is closer to either the receiving or excitation coil. Specifically, at an excitation frequency of 10 kHz, defects at different positions in the PM guide rod components can be more readily identified. A comparison of imaging quality indicates that the Tikhonov regularization algorithm provides superior reconstruction performance, as the notches and inclusions in the reconstructed images align more closely with the original model distributions. Hence, the Tikhonov regularization algorithm is more suitable for defect image reconstruction in PM guide rod components. This study provides a theoretical and methodological reference for enhancing the defect detection accuracy and imaging quality of EMT systems for PM guide rod products.

     

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