共查询到19条相似文献,搜索用时 109 毫秒
1.
导出了广义洛仑兹力的具体表达式,建立了壳体的非线性轴对称磁弹性方程,并讨论了广义洛仑兹力对磁场和机械场共同作用下载流薄圆柱壳体的力学及电磁效应的影响. 相似文献
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静磁场在材料生产过程中的应用研究评述 总被引:15,自引:0,他引:15
在材料电磁过程研究中,静磁场尤其是强磁场材料科学是当今世界的研究热点。本文从静磁场作用下生成的洛仑兹力和磁化力两个角度系统地归纳总结了静磁场技术在材料生产领域的应用原理和实践。对静磁场下的洛仑兹力,主要介绍了流体流动、波动和对流控制、电磁振动及电磁超声波等方面的研究现状;对强磁场下的磁化力,主要介绍了其在相变、结晶配向、磁悬浮、磁对流等方面的研究进展。最后对强磁场材料科学的研究趋势和发展前景做了展望。 相似文献
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《材料保护》1990,(7)
9007001 铝上锌合金浸渍膜的结构——Monteiro F.J.Metal Finishing,1989,87(10):49(英文) 在铝上电镀之前进行的二次锌酸盐处理之间加上一个用50%(体积)硝酸+2%(体积)HF处理的工序可提高铝上电镀层的结合力。浸酸处理后,并不能将第一次锌酸盐处理所生成的膜完全除去,而一个薄的、含铜量高的浸锌层仍存在于铝的表面,从而促进了第二次浸锌合金膜的多相成核过程,而此第二次生成的膜由较薄的、较细的和更致密的微晶组成,因此提高了铝上电镀的结合力。 9007002 在热浸锌时化学预处理对锌的消耗的影响——Riohard P.K.Metal Finishing,1989,87(10):37(英文) 相似文献
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本文通过中性盐雾试验以及电化学分析技术研究了铜铝/镍石墨封严涂层的腐蚀行为和腐蚀机制,中性盐雾腐蚀后铜铝/镍石墨显示出明显的腐蚀迹象,表面形成大量的腐蚀产物。通过对涂层的宏观形貌、显微组织、结合强度等性能进行测试分析,掌握了铜铝/镍石墨封严涂层盐雾腐蚀后的性能衰变特征。利用高速刮擦试验机模拟高压压气机叶片与封严涂层的刮擦行为,研究了喷涂态以及腐蚀态的铜铝/镍石墨封严涂层与高温合金模拟叶片试件的磨损行为。结果表明:在高速刮削条件下,喷涂态以及腐蚀态的铜铝/镍石墨封严涂层与高温合金叶片的磨损机制为涂层剥落和叶片氧化磨损机制。高温合金叶片与腐蚀态的铜铝/镍石墨封严涂层对磨后,涂层表面状态恶化,涂层更容易剥落,叶片磨损情况变化不大。 相似文献
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用磁场的协同作用改善Cu2+的扩散性能和强化铜电解的自净化过程,使阴极铜的质量提高。从离子磁性和离子水合作用的角度,进行不同流速下强磁场磁化铜电解液的实验,研究了洛伦兹力和磁场梯度力对Cu2+扩散性能、杂质离子浓度和阴极铜表观质量的影响,分析了垂直取向磁场和水平取向磁场强化铜电解的机理。结果表明:磁场能强化对流、减弱氢键缔合程度、降低离子水合作用、提高体系能量、促进Cu2+扩散性能和砷锑铋等杂质离子的沉降速度,从而提高电解液的清晰度和增强阴极铜表观质量;但是,磁场增加微气泡和溶解氧量并随着循环流速的提高而增大,使电解液表面张力增大而导致磁场的协同作用失效。在磁化铜电解过程中,存在一个提高阴极铜质量的最佳循环流速。 相似文献
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Minxian Liu Yiyun Lu Guangtong Ma Suyu Wang 《Journal of Superconductivity and Novel Magnetism》2011,24(4):1339-1344
In the present High Temperature Superconducting (HTS) maglev vehicle system, the nonuniformity of the magnetic field along
the movement direction above the NdFeB guideway is inevitable due to the assembly error and inhomogeneity of the material
property of the NdFeB magnet. In order to investigate the influence of the nonuniformity on the levitation performance of
the HTS bulk, the experiment involved an electromagnet, which is supplying AC current to simulate the nonuniformity of the
external magnetic field. The levitation force of the HTS bulk is measured when applying AC current on the electromagnet coils.
The results indicate that the levitation force abruptly changes and oscillates after applying AC external magnetic field.
The effect of the amplitude of the AC magnetic field on the levitation force is studied; the result shows that the oscillation
amplitude of the levitation force increases with the amplitude of the AC external magnetic field and is independent of the
Field Cooling Height (FCH) of the bulk. 相似文献
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Minxian Liu Suyu Wang Jiasu Wang Guangtong Ma 《Journal of Low Temperature Physics》2009,155(3-4):169-176
In the present High Temperature Superconducting (HTS) maglev vehicle system, the nonuniformity of the magnetic field along the movement direction above the NdFeB guideway is inevitable due to the assembly error and inhomogeneous of the material property of the NdFeB magnet. In order to investigate the influence of the nonuniformity on the levitation performance of the HTS bulk, an electromagnet supplied by AC current is used to simulate the nonuniformity of the external magnetic field. The levitation force of the HTS bulk is measured when applying AC currents to the electromagnet coils. Experimental results indicate that the levitation force changes abruptly and then oscillates after applying AC external magnetic field, and the levitation force is attenuated by the AC magnetic field after withdrawing the AC field. Moreover, the oscillation amplitude and the attenuation rate of the levitation force increase with the amplitude of the AC external magnetic field. 相似文献
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Minxian Liu Yiyun Lu Suyu Wang Guangtong Ma 《Journal of Superconductivity and Novel Magnetism》2011,24(5):1559-1562
The levitation force of the YBCO bulk over an NdFeB guideway used in the high-temperature superconducting (HTS) maglev vehicle
system is oscillated by the application of the AC external magnetic field. In our previous work, we interpreted that the oscillation
is due to the shielding current fluctuation caused by fluctuant external magnetic field. In this paper, based on the Bean
model, an analytical model is adopted to evaluate the levitation force. Comparing with the experimental results, the calculated
results show good matching. The model can reveal the oscillation characteristics of the levitation force of HTS bulk which
is being exposed to AC external magnetic field. Therefore, the levitation force oscillation of the HTS bulk in the maglev
vehicle system can be evaluated by this numerical method. 相似文献
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磁流体浸没物磁场力分析及磁浮特性 总被引:1,自引:1,他引:1
物体浸没于磁流体中表现出磁浮特性,对其受力状态分析是准确描述其悬浮状态的前提和基础。基于非线性磁流体应力张量模型和稳态Bernoulli方程,建立磁流体中浸没物受力模型。借助非磁性体受力模型的简化计算方法以及磁性体与磁流体之间的多场效应关系,分别对非磁性体、磁性体两类浸没物在磁流体中所受磁浮力进行分析,结果表明非磁性浸没物在磁流体中仅受到外加磁场贡献的一次磁浮力,而磁性浸没物除受到一次磁浮力外,还受到其自身激发磁场贡献的二次磁浮力.永磁体在磁流体中位置决定的磁浮力满足一定条件时,永磁体能够自悬浮于磁流体中。 相似文献
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Minxian Liu Yiyun Lu Suyu Wang Guangtong Ma 《Journal of Superconductivity and Novel Magnetism》2011,24(5):1809-1813
In the present High-Temperature Superconducting (HTS) maglev vehicle system, the air gaps between the adjacent permanent magnets
make the magnetic fields above the NdFeB guideway non-uniform. So one is required to study the characteristics of levitation
force of the HTS bulk influenced by non-uniform fields. In this paper, we have studied the characteristics of the levitation
force relaxation by an experiment in which the AC external magnetic field generated by an electromagnet is used to simulate
the time-varying external magnetic field caused by the inhomogeneity of the NdFeB guideway. From the experiment results, it
is found that the levitation force is attenuated with the application of the AC external magnetic field, and the decay is
increased with the amplitude of the AC magnetic field, but the decay is almost independent of the frequency of the AC magnetic
field. 相似文献
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Huan Huang Jun Zheng Botian Zheng Nan Qian Haitao Li Jipeng Li Zigang Deng 《Journal of Low Temperature Physics》2017,189(1-2):42-52
In order to clarify the correlations between magnetic flux and levitation force of the high-temperature superconducting (HTS) bulk, we measured the magnetic flux density on bottom and top surfaces of a bulk superconductor while vertically moving above a permanent magnet guideway (PMG). The levitation force of the bulk superconductor was measured simultaneously. In this study, the HTS bulk was moved down and up for three times between field-cooling position and working position above the PMG, followed by a relaxation measurement of 300 s at the minimum height position. During the whole processes, the magnetic flux density and levitation force of the bulk superconductor were recorded and collected by a multipoint magnetic field measurement platform and a self-developed maglev measurement system, respectively. The magnetic flux density on the bottom surface reflected the induced field in the superconductor bulk, while on the top, it reveals the penetrated magnetic flux. The results show that the magnetic flux density and levitation force of the bulk superconductor are in direct correlation from the viewpoint of inner supercurrent. In general, this work is instructive for understanding the connection of the magnetic flux density, the inner current density and the levitation behavior of HTS bulk employed in a maglev system. Meanwhile, this magnetic flux density measurement method has enriched present experimental evaluation methods of maglev system. 相似文献
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Minxian Liu Suyu Wang Jiasu Wang Guangtong Ma 《Journal of Superconductivity and Novel Magnetism》2008,21(7):431-435
For the permanent magnet guideway (PMG) of the high temperature superconducting (HTS) magnetic levitation (Maglev) vehicle
system, there should be many air gaps between two adjacent permanent magnets by connecting, which may fluctuate magnetic field
in the propulsion direction of the vehicle. A three-dimensional (3D) model of a PMG is built up using FLUX 3D software. The
magnetic field density of an NdFeB PMG is measured and simulated by 3D and 2D models. Comparison among their results indicate
that the simulation results of the 3D model agree better with the measuring results than that of the 2D model, and thus the
3D model is more suitable to describe the PMG. By the model, the influence of the air gap on the uneven of the magnetic field
density in the propulsion direction is studied. It is found that the magnetic field 15 mm above the PMG is roughly even in
the propulsion direction, although the magnetic field at 2 mm is not even. Since the working height 15 mm is a sensitivity
parameter for the onboard high temperature superconductor (HTSC), the levitation force at working height 15 mm above PMG is
measured, which indicates that the influence of the air gap on the levitation force is very small so as to be ignored in the
quasi-static state. 相似文献
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The superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a system, the nonuniformity of the magnetic field along the movement direction above the NdFeB guideway is inevitable due to the assembly error and inhomogeneity of the material property of the NdFeB magnet. So it is required to study the characteristics of levitation force of the bulks affected by the non-uniform applied magnetic fields along the moving direction. In this paper, we will study the characteristics of the levitation force relaxation between the HTS bulk and the NdFeB guideway by an experiment in which AC external magnetic field generated by an electromagnet is used to simulate the time-varying external magnetic field caused by the inhomogeneity of the guideway. From the experimental results, it has found that the levitation force is decreasing with the application of the AC external magnetic field, and the decay increasing with the amplitude of the applied magnetic field and is almost independent of the frequency. 相似文献
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S. T. Pan S. Y. Wang D. H. Jiang J. S. Wang 《Journal of Superconductivity and Novel Magnetism》2011,24(5):1677-1681
In the application of high temperature superconducting (HTS) magnetic levitation (maglev) system under vertical inclination
of permanent magnetic guideway (PMG), the component of the total weight of levitation body above the PMG will be changed.
Therefore, the influence of the vertical inclination of PMG on levitation characteristics of HTS maglev system cannot be ignored,
such as the levitation gap, the levitation force, guidance force and driving force of the linear motor. In order to investigate
the influence of the vertical inclination angle on levitation characteristics of the HTS maglev system, a HTS maglev launch
platform has been designed and fabricated for the investigation the influence of vertical inclination angle between the range
of 0° and 18° on the levitation and guidance and driving force parameters of the HTS maglev launch platform. Experimental
results show that the levitation gap was the main levitation characteristic for HTS maglev system under vertical inclination
of PMG, which increased with increment of the vertical inclination angle. However, the levitation force, and the driving force
of the linear motor decreased. The guidance force could not be influenced by the increment of levitation gap. The experimental
results are helpful toward improving the running performance of the HTS Maglev launch system. 相似文献