基于磁路法的液压换向阀用磁流变阻尼器研究

以双线圈内绕型剪切阀式磁流变阻尼器为研究对象,根据其磁场自封闭性,采用磁路法建立磁路数学模型。通过关键结构参数进行定性分析,得到活塞台阶间隙处磁感应强度近似化的结构优化依据。利用Ansoft Maxwell有限元仿真软件进行验证,结果表明：对于双线圈甚至多级线圈的内绕型剪切阀式磁流变阻尼器,采用磁路法进行初期设计计算有效且精确。     

基于APDL的磁流变阻尼器磁路结构的优化设计

磁路结构设计的优劣决定了磁流变(MR)阻尼器的性能品质。应用ANSYS的参数化编程语言(APDL)对MR阻尼器的磁路结构进行参数化建模。通过设置磁路结构各尺寸为设计变量、以模型中最大磁感应强度值为约束条件、以阻尼通道间的最大磁感应强度值为目标函数,进行优化分析。分析结果表明:优化后的磁路结构在阻尼通道处的磁感应强度提高了0.32倍,且分布更加均匀;优化后磁路结构的体积减小了7%,使磁路结构更加紧凑。说明APDL优化分析是一种设计磁路结构的切实高效的方法。     

磁流变减振器的优化设计与实验研究

磁流变减振器的磁路结构是磁流变减振器设计的重要环节,该结构的好坏将直接影响到减振器的工作性能的优良。采取参数化仿真的方法,分析得到了磁路的关键结构参数对间隙磁路的磁感应强度的影响,针对设计目标,选取设计变量,建立磁路的仿真模型。在磁流变减振器的设计中引入有限元分析的优化设计过程,采用参数化语言编程对模型结构参数进行优化。加工磁流变减振器样机,实验验证优化效果。仿真分析及实验结果均表明:运用参数化语言编程对磁流变减振器的磁路结构进行优化设计后,间隙处的磁感应强度得到明显改善,能够满足设计目标,磁场分布更加合理,是一种有效的磁路优化方法。     

并联式磁流变阻尼器磁场分布分析

为了更好地利用长行程磁流变阻尼器阻尼通道内磁场有效面积及控制的灵活性,实现对冲击力和位移的平稳控制,对阻尼器进行了磁场有限元仿真与分析,给出了4个线圈输入电流不同时阻尼通道内有效长度上的磁感应强度分布的非参数化模型。结合冲击载荷下控制目标,为控制算法的设计奠定了基础。     

两种磁流变阻尼器的结构设计与性能分析

针对传统磁流变(MR)阻尼器阻尼通道利用率低的问题,提出了两种磁路结构的优化设计方案。运用ANSYS软件对这两种MR阻尼器的磁路结构进行二维电磁场有限元仿真,分析结果表明两种MR阻尼器磁路结构设计切实可行。采用Bingham模型对两种阻尼器输出力进行预估并得到不同工作状态下的力-速度曲线,结果表明:由于增加了阻尼通道的有效长度,两种改进的阻尼器比活塞尺寸相同的传统阻尼器的最大出力提高1倍以上。     

基于磁场及动态响应的磁流变阻尼器结构分析

根据阻尼力理论数学模型分析减振器结构设计,并基于有限元仿真建立磁路结构模型,深入剖析不同磁路结构对磁场分布特性的影响以及对动态响应的影响。结果表明：小的阻尼间隙有利于增加磁感应强度并减小响应时间,活塞有效长度的增加在减少响应时间的同时也减小磁感应强度,磁极形状对二者的影响都较小。综合考虑磁场分布及响应时间,给出活塞头合理结构参数区间,为磁流变减振器的结构设计与优化提供参考。     

多级调压型磁流变阀结构优化设计

根据磁流变液在磁场作用下的可控可逆特性,在传统磁流变阀阀芯上缠绕三组励磁线圈,与阀体一起组成4个可变阻尼间隙,形成一种外侧圆环阻尼间隙多级调压型磁流变阀。采用ANSYS有限元仿真软件对多级调压型磁流变阀进行了磁场仿真,得出了磁力线分布和磁感应强度大小。基于仿真后处理数据对磁流变阀进行了结构优化,得出了该磁流变阀的最佳结构参数,并对结构优化前后阻尼间隙处的磁感应强度以及进出口阀压差进行了对比分析。相关优化设计方法和思路对磁流变阀设计具有一定的理论指导意义。     

应用于某型飞机起落架的双通道磁流变减震器结构设计与磁路优化

针对某型飞机起落架减震要求,设计了一种双阻尼通道式磁流变减震器,双阻尼通道增大了磁流变液流经环形间隙时的黏滞阻尼力以及库仑力的调节范围,磁流变减震器的可控性更高。根据电磁场理论对磁路进行了初步设计计算,并采用ANSYS有限元分析软件对磁流变减震器结构参数进行了进一步优化。通过优化分析得到了最有利于发挥减震器性能的结构参数,减震器结构更加紧凑,磁场分布更加合理,磁场利用率比初始设计提高了1倍多。     

双线圈磁流变阀压降特性分析

利用磁流变液体的可控特性,基于传统单线圈磁流变阀结构,设计一种双线圈圆环阻尼间隙磁流变阀。采用Maxwell电磁场仿真软件对双线圈磁流变阀进行磁场仿真,得出外加电流与阻尼间隙处磁感应强度大小的关系。建立双线圈磁流变阀压降数学模型,采用MATLAB数值仿真软件对磁流变阀压降特性进行仿真分析,初步得到了磁流变阀结构参数对压降的影响规律,从而为双线圈磁流变阀多级调压提供了一定的理论参考。     

磁流变阻尼器动态响应分析

磁流变阻尼器的动态响应决定了其实时控制效果,为了增加磁流变阻尼器响应速度和减小响应时间,对其动态响应影响因素进行分析。针对某型号磁流变阻尼器,定义其响应时间的组成,建立时滞模型。建立了两级线圈同向串联、反向串联、同向并联、反向并联的电流及磁场响应模型,分析磁流变液两阶段的流变响应模型,得到反向串联与反向并联的电磁响应时间较小,且流变响应仅与间隙与动力黏度有关。并基于瞬态有限元磁场分析,从平均有效剪切屈服强度的角度来衡量阻尼器的动态响应过程,得到了不同磁路结构对阻尼器响应时间的影响及其影响原因。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

The 15th Global Foundry Sourcing Conference 2014held in Qingdao China

Organized by Suppliers China Co., Ltd and co-organized by the National Technical Committee 54 on Foundry of Standardization Administration of China, the 15th Global Foundry Sourcing Conference 2014 （hereinafter referred to as FSC 2014） was successfully held on Sep. 23rd in Grand Regency Hotel, Qingdao. More than 500 delegates from home and abroad attended this conference, including over 130 purchasers from 20 countries and 380 domestic and foreign suppliers.     

Secondary Recrystallization Behaviors of Grain-Oriented 6.5 wt% Silicon Steel Sheets Produced by Rolling and Nitriding Processes

By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 k Hz were lower than that of the grain-oriented 3 wt% silicon steel with the same thickness by 16.6–35.8%. The secondary recrystallization behavior was investigated by scanning electron microscopy, energy-dispersive spectroscopy, and electron backscattered diffraction. The results show that the secondary recrystallization in high-silicon steel sheets develops more completely as the nitrogen content increases after nitriding, secondary recrystallized grain sizes become larger, and the sharpness of Goss texture increases. Because more {110}116 grains in the subsurface and the central layer of the sheets have a lot of 20°–45° high-energy boundaries in addition to Goss grains, {110}116 can be the main component through selective growth during secondary recrystallization when the inhibitor quantity is not enough and inhibitor intensity is weaker. The increases in nitrogen content can increase the inhibitor intensity and hinder abnormal growth of a mount of {110}116 grains and therefore enhance the sharpness of Goss texture.     

Laser Cladded TiCN Coatings on the Surface of Titanium

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80?滋m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

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正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis