共查询到19条相似文献,搜索用时 78 毫秒
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研究交变磁场下的焊缝裂纹磁化规律,针对碳钢(Q235)焊缝裂纹,进行交变电磁场励磁下焊缝磁光成像无损检测的仿真和试验. 基于交变励磁下焊缝励磁规律的仿真模型,研究裂纹间隙分别为0.03,0.05,0.07和0.1 mm的焊缝表面磁通密度(磁感应强度)模曲线分布差异. 钢板对接间隙分别限定为0.03,0.05,0.07和0.1 mm后,通过激光焊接钢板两端来模拟仿真试验中的裂纹. 进行磁光成像无损检测试验,并将试验结果与仿真结果进行对比. 结果表明,在仿真试验与工艺试验中,焊接裂纹感应磁场的变化规律基本相同,磁感应强度不会因采样起始点不同出现较大的差异. 相似文献
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利用ANSYS有限元软件模拟了3种不同缺陷形状在不同参数下对于漏磁场的影响。分析了漏磁场径向分量以及轴向分量在不同参数下的变化曲线,根据其变化趋势选取了合适的特征值,为实现智能化识别缺陷提供了基础。分别建立了矩形凹槽、平滑凹坑和穿孔3种不同缺陷的漏磁场三维ANSYS模型,分别改变其磁化装置的气隙高度、缺陷宽度和缺陷深度3种参数,得到3种不同缺陷的漏磁场轴向曲线与径向曲线,分析研究了3种参数对于漏磁场的影响,根据其变化趋势选取了4种不同的特征值,通过t-SNE算法对4种不同特征值进行降维可视化,将其从高维空间降维至二维空间,验证了所选取的4种特征值能够明显地区分不同的缺陷类型,为通过计算机实现智能化识别缺陷类型提供了基础。 相似文献
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以压力容器等焊接设备对接焊缝为对象,提出了一种基于数值模拟的焊缝缺陷漏磁场的分析方法。通过仿真分析,对比分析了不同焊接工艺(单面焊和双面焊)无缺陷、焊道上分布矩形槽缺陷及热影响区分布矩形槽缺陷时的漏磁场特征,评述了单面焊同时分布两个矩形槽缺陷对漏磁场分布的影响规律。数值模拟结果表明:双面焊这种结构对于焊道上分布矩形槽时的漏磁场的影响更大;两个缺陷同时存在时,缺陷之间的距离是影响缺陷漏磁场分布的主要因素。 相似文献
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由磁偶极子理论证明,表面开口缺陷引起的漏磁场H正比于(d/2-kδ),其中d是缺陷深度,而δ是取决于工件和缺陷横截面的形状与尺寸的一较小长度,k是一个系数,它取决于缺陷侧壁上的磁荷分水岭。从而可以得出结论,当d很小时,H与d间近似为线性关系;而d增大时,它们之间则呈非线性关系。 相似文献
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平行钢丝束作为缆索桥梁的关键受力构件,直接影响桥梁结构的安全。基于漏磁检测原理,利用柔性桥索检测传感器对平行钢丝束典型缺陷进行检测。采用点检测和线扫查两种检测方式,研究了圆形和扇形两种排布方式下不同平行钢丝束的填充状态对表层缺陷漏磁场的影响。针对观察到的平行钢丝束填充会减小表层缺陷漏磁场强度的现象,提出了一种用于预测该弱化规律的模型,在缺陷钢丝周围有、无平行钢丝束填充的两种状态下研究了不同位置表层缺陷的漏磁场分布,得出了两种填充状态下缺陷漏磁场与缺陷位置的关系。 相似文献
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磁场复合电解加工间隙磁场的有限元分析 总被引:2,自引:0,他引:2
为了研究永磁体不同设置对磁场复合电解加工间隙磁场分布的影响,建立了磁场复合电解加工间隙磁场分析的数学模型和有限元模型,采用ANSYS软件对其进行了分析。结果表明:当永磁体置于阳极下方且磁化方向垂直于阳极时,磁场对电解加工几乎无影响;而当永磁体置于阳极下方且磁化方向平行于阳极时,间隙中的磁场强度较为均匀且磁场方向与电场方向垂直,有利于提高电解加工的效率和型面的加工精度。分析结果与试验结果一致。 相似文献
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Numerical analysis of external magnetic field for mitigating backward flow momentum in weld pool 下载免费PDF全文
The external magnetic field is applied to mitigating backward flow jet of molten metal in weld pool so that humping bead may be suppressed during high speed gas metal arc welding(GMAW). Therefore, the external magnetic field distribution in workpiece is critical to understand the interaction mechanisms of the external magnetic field with molten metal flow. In this study, the steady state external magnetic field induced by excitation device is numerically analyzed by using the the finite element software ANSYS and the three dimensional static magnetic scalar method. The distribution of external transverse magnetic field By in workpiece and arc area is calculated, and the influence of excitation current and air-gap distance on the distribution of transverse magnetic field By has been discussed. The magnetic field distribution in workpiece is measured by using a Tesla-Meter and compared with the simulated result. It is found that both are in good agreement. 相似文献
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Experiment and simulation study of 3D magnetic field sensing for magnetic flux leakage defect characterisation 总被引:1,自引:0,他引:1
Magnetic flux leakage (MFL) testing is widely used to detect and characterise defects in pipelines, rail tracks and other structures. The measurement of the two field components perpendicular to the test surface and parallel to the applied field in MFL systems is well established. However, it is rarely effective when the shapes of the specimens and defects with respect to the applied field are arbitrary. In order to overcome the pitfalls of traditional MFL measurement, measurement of the three-dimensional (3D) magnetic field is proposed. The study is undertaken using extensive finite element analysis (FEA) focussing on the 3D distribution of magnetic fields for defect characterisation and employing a high sensitivity 3-axis magnetic field sensor in experimental study. Several MFL tests were undertaken on steel samples, including a section of rail track. The experimental and FEA test results show that data from not only the x- and z-axes but also y-axis can give comprehensive positional information about defects in terms of shape and orientation, being especially advantageous where the defect is aligned close to parallel to the applied field. The work concludes that 3D magnetic field sensing could be used to improve the defect characterisation capabilities of existing MFL systems, especially where defects have irregular geometries. 相似文献
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This paper describes analytical expressions for the magnetic leakage field of two types of internal defects: two dimensional rectangular and elliptical defects as functions of the applied magnetic field strength, the defect size and the distance below the surface. In this study, the magnetic image effects from the spatial boundary and the defect boundary are taken into consideration. That is, the leakage field of rectangular-like defects or elliptically shaped defects ‘below the surface’ are derived by using the modified dipole model and image theory. The profiles and strengths of leakage fields calculated from the proposed analytical forms are presented under various conditions and compared with experimentally measured ones. 相似文献
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为了实现对焊缝表面缺陷的自动检测与分类,研究一种有效识别焊缝表面缺陷的激光视觉检测方法. 通过激光视觉传感器采集焊缝图像并进行预处理,包括图像分割,灰度化,平滑去噪以及焊缝轮廓提取. 采用方向梯度直方图(Histogram of Oriented Gradient, HOG)提取焊缝激光条纹轮廓图像的特征向量. 其次,基于5折-交叉验证网格搜索方法进行模型参数寻优,最终建立了支持向量机(Support Vector Machine, SVM)智能模型识别与分类焊缝表面缺陷. 通过调整焊缝轮廓提取算法、HOG特征维度得到不同特征数据并进行对比、分析焊缝缺陷的识别效果. 在相同试验条件下,发现支持向量机比随机森林分类器、K最近邻分类器以及朴素贝叶斯分类器的识别率更高,达到97.86%. 基于HOG-SVM的焊缝表面缺陷智能识别方法可有效提高焊缝缺陷(气孔、凹陷、咬边)及无缺陷的分类精度. 相似文献
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磁场分布是影响磁粒研磨加工的重要因素之一,研究磁场分布的主要方法是数值计算法,本文介绍了旋转磁场磁粒研磨加工的基本原理,并用有限元法对旋转电磁场进行了计算,得到了一些重要结论。 相似文献