共查询到20条相似文献,搜索用时 204 毫秒
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智能材料的概念出现于 80年代末 ,由于它集感应功能和驱动功能于一身 ,很快就引起了全世界的注意。形状记忆合金 (SMA)能够在温度或载荷的一定范围内变化时产生热弹性马氏体相变 ,由此改变应力状态和其他性质 ,所以SMA可作为智能材料中的感应和驱动单元。可以把 SMA作成颗粒状、丝状或带状嵌入母相基体 ,如聚合物、金属或陶瓷中。通过控制 SMA热循环时的马氏体转变进程来提高或改变材料性能。比如嵌入的预应变 SMA在加热过程中产生马氏体相变 ,对周围母相产生压应力 ,可强化材料 ,提高材料抗冲击和减振性能 ,或改变材料固有振动频率 ,… 相似文献
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一、钢管的焊接方法的发展近几年来,世界各国在钢管焊接工艺上有了重大的改革。普遍在原低频焊管的基础上发展为100~450仟周/秒的高频电阻接触焊和感应焊。这种焊接工艺的特点是:金属在加热时电能的高度集中,用1/10甚至~1/100秒就可以使金属加热到焊接温度(1300~1350℃)。由于高频电流的集肤效应和邻近效应,焊接电流将沿管坯边缘很薄的一层通过,因此,热影响区窄,加热时间短,从而生成的氧化物减少,这就为提高焊接质量创造了有利条件。实践证明,采用频率为450仟周/秒的高频电流焊管同低频焊管比较具有许多优点: 相似文献
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在天津大无缝钢管厂生产中,为了实现钢管涂漆后烘于的目的,采用了中频感应加热方式取代传统的燃气加热炉加热方式,既达到了均匀加热钢管的目的又实现了节能降耗。主要介绍了应用感应加热原理进行钢管涂漆烘于的技术特点,重点分析了该设备所装备的IGBT全固态中频感应电源的组成结构和工作原理,并结合使用实例,分析了与传统加热相比的优越性。 相似文献
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利用商业软件ANSYS对电炉熔体部分进行了模拟计算,并研究了恒功率下不同的电极插入深度对熔体的焦耳热场和温度场的影响.结果表明:随着电极插入深度的变化,靠近电极区域的焦耳热有明显的变化,而远离电极区域的焦耳热变化相对较小;温度与焦耳热分布类似,电极插入越深,熔体底部温度升高,顶部温度减小,并且靠近电极区域的温度变化更加明显. 相似文献
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Finite Element Analysis of 3-D Electromagnetic Field in Bloom Continuous Casting Mold 总被引:2,自引:0,他引:2
Three-dimensional finite element model of electromagnetic stirrer was built to predict magnetic field in a bloom continuous casting mold for steel during operation.The effects of current intensity,current frequency,and mold copper plate thickness on the magnetic field distribution in the mold were investigated.The results show that the magnetic induction intensity increases linearly with the increase in current intensity and decreases with the increase in current frequency.Increasing current intensity and frequency is available in increasing the electromagnetic force.The Joule heat decreases gradually from surface to center of bloom,and a maximum Joule heat can be found on corner of bloom.The prediction of magnetic induction intensity is in good agreement with the measured values. 相似文献
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Baokuan Li Bo Wang Fumitaka Tsukihashi 《Metallurgical and Materials Transactions B》2014,45(3):1122-1132
A three-dimensional finite-element model has been developed to understand the electromagnetic field and liquid metal pool shape in an electroslag remelting (ESR) process with two series-connected electrodes. The magnetic vector potential is introduced into the Maxwell’s equations, and the nodal-based method is used to solve a three-dimensional harmonic electromagnetic field. The heat transfer of the solidifying processes of ingot is modeled by a source-based enthalpy method, and the Joule heating is included in an inner source. The results show the main part of the current flows through the slag cap and a little enters into ingot in a two-series-connected electrode ESR system. As the interaction of self-induced and mutual-induced of two electrodes occurs, the skin effect is significantly suppressed by the neighbor effect. A symmetrical pattern of magnetic flux density in a two-series-connected electrode ESR system is displayed. The magnetic flux density between two electrodes is reinforced and reduced at the outside of two electrodes. The maximum Joule heat power density is located at the interface of slag and electrodes, and it decreases with an increase of the electrode immersion depth. The averaged Joule heat power density increases when slag cap thickness is reduced. With the increase of ingot height, the liquid metal pool shape changes from arc shaped to “V” shaped. When the ingot height is more than the diameter in the ESR processes, the liquid metal pool shape is constant. 相似文献
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钢管缺陷漏磁场及影响漏磁信号因素的分析 总被引:6,自引:0,他引:6
介绍了钢管检测中常见的缺陷漏磁场模型和漏磁场分布,以及对凹坑缺陷漏磁场进行的模拟研究。比较了两种缺陷漏磁检测信号的时频特性,讨论了缺陷深度、励磁电流、检测探头纵向旋转速度等对矩形槽缺陷漏磁感应电压信号的影响。研究发现,缺陷深度和漏磁感应信号峰值约呈线性关系,这可作为钢管缺陷检测的应用基础。 相似文献
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《Baosteel Technical Research》2012,6(2):44-48
In the production of pipes by hot extrusion method,billets should be heated to a certain temperature before hot extrusion by induction heating. The segmented liners in the induction furnace can possibly affect the circumferential Joule heat generation,thus leading to an uneven temperature field. The commonly used magnetic flux concentrators ( MFC) can increase the temperature on both ends of the billet. In this paper,the possible effect of liners and the factors affecting the utilization of the MFC,including the permeability,dimension and position,are all numerically studied and determined. 相似文献
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以特殊钢圆坯连铸为研究对象, 建立了研究凝固末端电磁搅拌作用效果的三维耦合数值模型.利用分段计算模型获得末端电磁搅拌区域钢液流动与凝固的实际状态, 并采用达西源项法处理凝固末端钢液在糊状区的流动, 研究了不同电磁搅拌工艺参数下的电磁场分布及钢液的流动与传热特征.通过测量搅拌器中心线磁感应强度和铸坯表面温度验证了模型的准确性.研究结果表明: 电流强度每增加100 A, 搅拌器中心磁感应强度增加19.05 mT, 电磁力随着电流强度的增加显著增大.在20~40 Hz范围, 随着电流频率的提高, 中心磁感应强度略微下降, 但电磁力仍有所增加.在搅拌器区域, 液相穴内的钢液在切向电磁力的作用下旋转流动, 其切向速度随着电流强度和频率的增加而变大.末端电磁搅拌可促进钢液在圆坯径向的换热, 随着电流强度和频率的提高, 铸坯中心轴线上的钢液温度降低, 同时末端搅拌位置处的中心固相分率增加. 相似文献
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随着节能减排的生态发展理念深入人心,如何最大限度地提高能源的利用率,成为时下研究的热点.文中以多头螺旋管为研究对象,并以当量直径的光管作为基准管,运用有限元分析软件ANSYS对模型的传热过程进行数值模拟,得出了换热过程中温度场与流场的分布状况,而后结合传热学中的边界层理论和协同场理论对结果进行综合分析.结果表明:在等热流的情况下,多头螺旋管的换热性能明显优于光管,相对光管,多头管内流体的出口温升相对提高了2.6倍,出口速度相对下降50%;其特殊的内外凸筋结构,是强化传热的主要原因,同时,凸筋造成流体的有涡流动,也使得多头螺旋管管壁不易结垢. 相似文献
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Zhen-guo YANG Bao WANG Xiao-feng ZHANG Ya-tao WANG Hong-biao DONG Qing LIU 《钢铁研究学报(英文版)》2014,21(12):1095-1103
The effect of electromagnetic stirring on molten steel flow and heat transfer in a 260 mm× 300 mm bloom mold was investigated by using a method combining both finite element method and finite volume method. The simu lation results related to magnetic fields were consistent with the onsite measured data. The magnetic flux density in creased with increasing the current intensity but decreased with increasing the current frequency. Electromagnetic stirring caused molten steel to flow with rotation on a horizontal section and two sets of recirculation regions with opposite fellow directions in a longitudinal section formed. The maximum tangential velocity increased with increasing the current intensity and frequency. Furthermore, the superheat degree of the molten steel on the outlet cross section of the mold decreased with increasing the current intensity. growth zone of solidified shell in the effective stirring zone. bearing steel, the appropriate values of current intensity and to be 300 A and 3 Hz, respectively. Electromagnetic stirring caused the emergence of a zero For the 260 mm N 300 mm bloom continuous caster of current frequency of electromagnetic stirring were found 相似文献
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利用有限元分析软件ANSYS求得稳定电渣重熔过程电极、渣池和钢锭系统电磁场和焦耳热场分布,并通过计算流体力学软件FLUENT模拟分析了耦合电磁场和焦耳热场的三维电渣重熔过程电极填充比0.3~0.7对电渣重熔系统温度场、速度场和电磁场的影响。结果表明,随着电极填充比的增加,速度最大值和湍动能最大值逐渐增加,但变化速率随填充比增加而下降;填充比0.3和0.5之间的最大湍动能差值约为填充比0.5和0.7之间湍动能的2倍;温度最大值随填充比不是单调变化的。 相似文献