共查询到19条相似文献,搜索用时 218 毫秒
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方钢纵向磁化初瞬间各截面的退磁场和净磁荷 总被引:6,自引:6,他引:0
首先推导出方钢纵向磁化初瞬间的退磁场解析表达式,据此和磁介质的磁化规律可证明,此刻在垂直于磁化场的各截面上将出现不同的净磁荷,从而得出方钢纵向磁化初瞬间的磁荷分布是不稳定的结论. 相似文献
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根据穿棒法产生的磁场分布和磁介质的磁化规律,给出了圆盘边缘柱面上沟槽棱线上磁荷密度和漏磁场的解析表达式,计算了它们的数值并画出其空间分布图,理论分析与磁粉探伤的经典实验基础一致。 相似文献
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磁偶极子链的横向排斥 总被引:8,自引:8,他引:0
由磁荷间的磁力和磁荷体系的相互作用能量推证出,磁化时磁介质内形成的磁偶极子链必有横向排斥,从而使这些磁偶极子链均匀地充满磁介质的横截面积,但每种磁介质单位横截面积所能容纳的磁偶极子链数目是有限的,故工件中不连续性缺陷使工件横截面的减小迫使某些磁偶极子链在工件表面上断开,形成正、负磁极(荷),这样就自然而然地阐明了工件表面下的不连续性在工件表面上方产生漏磁场的原因。 相似文献
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方钢纵向磁化的磁偶极子理论基础 总被引:10,自引:10,他引:0
本文从磁荷间的相互作用力和相互作用能出发,论证了长方体磁介质纵向磁化后磁荷将均匀地分布在所有各条棱线上,从而阐明了长方体纵向磁化后侧棱上出现非相关(杂乱)显示的原因。 相似文献
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方钢纵向磁化时各棱上的磁荷线密度 总被引:8,自引:8,他引:0
根据方钢纵向磁化原理(磁荷将均布于各条棱线上)和磁介质的磁化规律给出了方钢和带有矩形沟槽的方钢纵向磁化后各条棱线上的磁荷线密度近似解析表达式,并得出结论,工件表面沟槽深度与其引起漏磁场间的“直线律”关系仅是近似的。 相似文献
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方钢纵向磁化稳定状态的退磁场强度 总被引:2,自引:2,他引:0
根据方钢纵向磁化稳定状态下的磁荷分布规律(磁荷均布于各条棱线),给出了方钢内任意点退磁场强度的解析表达式和某些典型空间分布曲线,它们与磁化瞬间的对应曲线既有相似之处,也有不同特点,数值计算退磁场既有负值(传统意义的退磁场),也有正值(有效磁场大于磁化场)和零值(有效磁场与磁化场相等)。 相似文献
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工件表面矩形沟槽引起的漏磁场分析 总被引:1,自引:1,他引:0
按照矩形钢件的纵向磁化原理(磁荷必均匀地分布在试件的所有棱线上),给出了工件表面矩形沟槽引起的漏磁场的近似解析表达式,并通过数值计算绘出了沟槽对称轴上的磁场空间分布图。理论曲线与F.Foerster所做的经典试验结果基本相符。 相似文献
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分析了浸液复合磁化探伤装置所产生的合成磁场,结论如下:它是个平面旋转磁场,故与受检工件侧面圆柱面同心的弧状裂纹用穿棒法是检查不出来的,而工件的退磁因子与复合磁化法中所用的磁化方式无关。 相似文献
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20年来中国磁偶极子理论研究进展 总被引:5,自引:0,他引:5
简述20年来中国无损检测中磁偶极子理论研究的概况和进展,主要介绍磁偶极子,有限长磁偶极线和极带,磁粉颗粒的受力,磁化场方向对粉粉显现缺陷的影响,棒料,管材和方钢的纵向磁化,工件表面沟槽深度对其引起漏磁场的影响,周向磁化工时工件底棱上的杂乱显示成因,圆盘边缘柱面上沟槽内外漏磁场的蟹 表达式和针状磁介质对两个点磁荷间磁力的影响等。 相似文献
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漏磁通检测中铁磁材料的磁化状态 总被引:3,自引:3,他引:0
讨论缺陷引起的附加磁场和外磁化场对铁磁材料的磁化作用,引入有效磁导率和平衡磁导率来描述铁磁材料不同区域的磁化状态,建立铁磁材料中的磁化状态及磁偶极子模型中的关荷密度与外磁化场强度、铁磁材料的内禀磁性质以及铁磁材料中磁路和缺陷几何尺寸的关系。 相似文献
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G. Vrtesy I. Tom S. Takahashi S. Kobayashi Y. Kamada H. Kikuchi 《NDT & E International》2008,41(4):252-257
A series of low-carbon steel samples is investigated in the frame of a chain of magnetic non-destructive measurements on round robin samples, organized by the Universal Network for Magnetic Non-Destructive Evaluation. The samples have been plastically deformed by cold rolling to five consecutive stages of deformation. They are examined by the method of magnetic adaptive testing, typical by its low required magnetization of the samples. Results of the non-destructive magnetic tests are compared with the destructive mechanical measurements of Vickers hardness and ductile–brittle transition temperature. Linear, sensitive correlation is found between the magnetic parameters and the two mechanical ones. 相似文献
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Ni0.23Cu0.11Zn0.66Fe2O4 ferrite flakes, with thickness of about 8 μm and average diameter of 20-35 μm, were prepared using a sol-gel bubble method. Morphology, phase evolution, static and dynamic magnetic properties of the flakes and their composites were studied. Magnetic measurements showed that easy magnetization direction of the flaky filler composite was parallel to its sample plane. Composites made of silicone resins and flakes had higher complex permeability, which can be attributed to the reduction in demagnetization factor due to their flaky shapes. This sol-gel bubble method should be also applicable to fabricating flakes of other multi-component oxides. 相似文献
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In a paper, we reported that incorporation of diamond into composite coatings could cause microstructural deteriorations (e.g., roughening the coating surface, coarsening the matrix grain and reducing the mechanical retention of diamond grains in the matrix), and suggested that all the impacts were caused by diamond magnetism resulting from metallic inclusions trapped in it. To confirm this, further microstructural observations were conducted on composites containing diamond particles that experienced different treatments before being planted, i.e., magnetization (strengthening diamond magnetism by a strong magnet) and demagnetization (weakening diamond magnetism by an alternating magnetic field), as well as on composites fabricated in the presence of an external alternating magnetic field in the vicinity of the cathode. It is shown that advance demagnetization treatment reduces the impacts while advance diamond magnetization treatment does the opposite. Moreover, the impacts could be more effectively reduced by superimposition of the external alternating magnetic field which may exert effects not only on demagnetization of the diamond grains, but also on cations' deposition process since the external magnetic field is much stronger than that produced by diamond. 相似文献
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分析了浸液复合磁化探伤装置产生的合成磁场。结果表明,该合成磁场是个平面旋转磁场,故与受检工件侧面圆柱面同心的弧状裂纹无法用穿棒法检出,而工件的退磁因子与复合磁化法中所用的磁化方式无关。 相似文献