用H的棱边有限元法计算三维工程涡流问题

推导了在整个求解区域以Ｈ为变量求解三维稳态线性涡流场的公式。在涡流区采用棱单元离散,在非涡流区从节点元出发,利用节点元与棱单元插值函数的关系,推导出棱单元离散的加权余量公式。在推导过程中,自动消除了交界面处表面积分带来的方程组系数矩阵的非对称性,节省了内存。用此公式求解了ＴＥＡＭ ＷＯＲＫＳＨＯＰ ２１．０问题,对计算结果进行了分析。     

钢管自动涡流探伤系统设计

本文介绍用可编程序控制器设计的钢管自动涡流探伤设备．详述系统的硬件配置和程序设汁。设置探伤和调试两种工作状态．自动、半自动和手动三种工作方式，强化了抗干扰措施和故障检测处理能力。和已有的同类检测设备比较，该系统具有在线修改能力及较高的性能价格比。该设备在西宁钢厂、大连钢管厂等地运行了多年．效果良好。     

钢管自动涡流探伤系统设计

本文介绍用可编程序控制器设计的钢管自动涡流探伤设备,详述系统的硬件配置和程序设计。设置探伤和调试两种工作状态,自动、半自动和手动三种工作方式,强化了抗干扰措施和故障检测处理能力。和已有的同类检测设备比较,该系统具有在线修改能力及较高的性能价格比。该设备在西宁钢厂、大连钢管厂等地运行了多年,效果良好。     

Ultra-high cycle fatigue behavior of high strength steel with carbide-free bainite/martensite complex microstructure

The ultra-high cycle fatigue behavior of a novel high strength steel with carbide-free bainite/martensite (CFB/M) complex microstructure was studied. The ultra-high cycle fatigue properties were measured by ultrasonic fatigue testing equipment at a fre-quency of 20 kHz. It is found that there is no horizontal part in the S-N curve and fatigue fracture occurs when the life of specimens exceeds 107 cycles. In addition, the origination of fatigue cracks tends to transfer from the surface to interior of specimens as the fa-tigue cycle exceeds 107 , and the fatigue crack originations of many specimens are not induced by inclusions, but by some kind of "soft structure". It is shown that the studied high strength steel performs good ultra-high cycle fatigue properties. The ultra-high fa-tigue mechanism was discussed and it is suggested that specific CFB/M complex microstrueture of the studied steel contributes to itssuperior properties.     

A novel hybrid FEM-BEM method for 3D eddy current field calculation using current density J

To solve a large eddy current field is one of the most difficult problems in the numerical computation of electromagnetic field. For this purpose, currently, the FEM and the BEM are widely used. The former is good at dealing with the close regions, nonlinearity and complicated mediums and the latter is fit to solve the problems of open regions and linearity. However, for complicated eddy current field problems in electrical engineering, either the FEM or the BEM is not successful. Therefo…     

Control of magnetic levitation positioning stage with an eddy current damper

To enhance the system damping,a permanent magnet set which served as an eddy current damper was added to the magnetic levitation positioning stage which consists of a moving table,four Halbach permanent magnetic arrays,four stators and displacement sensors.The dynamics model of this stage was a complex nonlinear,strong coupling system which made the control strategy to be a focus research.The nonlinear controller of the system was proposed based on the theory of differential geometry.Both simulation and experimental results show that either the decoupling control of the movement can be realized in horizontal and vertical directions,and the control performance was improved by the damper,verifying the validity and efficiency of this method.     

棱边有限元法在工程涡流问题中的应用研究

结合近年来的科研工作,讨论了若干棱边有限元法在工程涡流分析中的应用问题,如棱单元矢量插值函数的统一导出方法、树规范问题、大型稀疏方程组迭代解法以及电磁场直接求解方法的研究,并比较了棱边有限元法与传统的节点有限元法各自的优劣。最后给出了待解决的问题。     

BP网络在电涡流传感器非线性修正中的应用

为解决电涡流传感器线性测量范围与传感器尺寸限制之间的矛盾，将BP网络用于扩大其线性测量范围．对于线圈直径为40mm的测量头进行实验，结果表明：在0～20mm范围内，未利用BP网络校正时传感器线性度很低，仅为20．44％，而校正后线性度大大提高，为1．58％，此结果说明了神经网络校正法的有效性．     

涡流检测压力管道时特征频率的合理选择

为满足对压力管道进行涡流检测的工程实际要求,提出了检测时特征频率如何选择．     

管道在使用放置式探头检测时的真实涡流特性参数分析

从电磁渗透方程入手,采用平板模型对管道中涡流的涡流密度、电阻、电抗等各种参数进行了求解.     

涡流检测中探头运动速度对检测信号的影响分析

主要从理论和实验两个方面对涡流检测时的探头运动速度对检测信号的影响进行了分析和研究,研究的结果对实际的检测具有很重要的指导意义.     

不锈钢管内壁腐蚀层厚度的涡流检测仿真

针对耐热奥氏体不锈钢内壁腐蚀层厚度测量难的问题,建立了典型腐蚀状态下奥氏体不锈钢结构的有限元仿真模型,提出了采用低频涡流检测内壁腐蚀层厚度,并用高频涡流测量外壁氧化层厚度以对低频检测结果进行修正的检测方法.结果表明,腐蚀层厚度增加会引起低频涡流检测信号幅值和阻抗模的增加,而外壁存在的氧化层会对检测信号造成干扰.腐蚀层厚度和氧化层厚度对涡流检测信号影响的变化规律与仿真结果具有一致性.     

永磁同步电机转子永磁体内涡流损耗密度的计算

针对钕铁硼永磁材料提出了一个计算永磁同步电机转子永磁体内涡流损耗密度的公式.通过三维电磁场有限元方法，求解了电机内的磁场并计算出了永磁体内的涡流损耗，验证了公式的正确性.在分析计算中考虑了电机复杂三维结构的特点，同时根据对称性，取电机的一个极范围作为分析的简化模型.为了能很好地分析和画出精确的涡流波形，对每一个周期取100个时间子步作瞬态分析，并且在划分有限元单元时考虑了磁场的透入深度.最后根据计算结果的比较得出影响永磁体内涡流损耗的因素.     

换热器不锈钢管的涡流检测

介绍双频涡流检测传感器的工作原理、设计和制作 ,验证了根据阻抗图幅度和相位分析判定缺陷技术优点     

高压直流换流站阀厅穿墙套管封堵材料的涡流损耗和屏蔽效能分析

基于麦克斯韦方程,推导获得了高压直流换流站阀厅穿墙套管封堵材料的涡流分布的解析解,并对影响封堵材料涡流损耗和屏蔽效能的有关因素,如谐波频率、材料厚度等进行了分析。结合500 kV直流换流站阀厅穿墙套管封堵材料的具体几何尺寸,对材料参数、工频和各次谐波电流等因素,分析了材料厚度与集肤深度、温升之间的关系。结果可为高压换流站阀厅穿墙套管封堵材料的开发和工程设计提供参考。     

钕铁硼永磁电机永磁体涡流发热退磁研究

为了研究永磁体涡流损耗发热对永磁体磁性的影响,应用有限元分析软件对一台发生退磁的500 kW永磁同步电动机的永磁体进行涡流损耗分析.在600 kW永磁同步电机的研制过程中,采取了一些结构改进措施,并对样机永磁体进行了涡流损耗分析和稳态温度场计算.仿真结果表明,涡流损耗发热会导致永磁体退磁,而采取的结构改进措施能够有效减小涡流损耗.样机实验结果表明,新结构永磁同步电动机运行可靠,可为相关电机的设计提供经验.     

Comparison and analysis of dislocation density, morphology and evolution in microstructure of low-carbon steel produced using different technologies

Three kinds of specimens were produced from hot strips of similar composition and same thickness （nominal gauge 4.0 mm） but produced using different technologies, and the dislocation density of these strips was quantitatively measured by positron annihilation technique test. The dislocation morphology and evolution in microstructure of each pass for producing the 1.9 mm hot strip using CSP （compact strip production） technology were observed under an H-800 transmission electron microscope; its density was also quantitatively measured using the positron annihilation technique test, and the factors influencing the dislocation density during the production process were analyzed. The experimental results show that the dislocation density in the microstructure produced using CSP technology is higher than that in the microstructure produced using conventional technology. This result was discussed and confirmed on the basis of the finite element simulation and the theory relevant to dislocations.