磁流变液阻尼器阻尼通道内部塞流区边界位置的分析

磁流变液阻尼器阻尼通道内部磁流变液运动时塞流区边界位置与输出阻尼力之间存在着密切联系。为了得到塞流区边界位置的具体数值和变化规律,基于RD-8041-1型磁流变液阻尼器,对阻尼通道内部磁流变液的剪切应力和流动状态进行了分析,并得到了塞流区边界位置与活塞运动速度之间的函数关系。为了验证所得函数关系的正确性,在推导出磁流变液阻尼器输出阻尼力数学表达式的基础上,根据塞流区边界位置与活塞速度之间的函数关系得到了磁流变液阻尼器在输入电流为1 A时的输出阻尼力,并将计算得到的阻尼力与实际试验测试值进行了对比。对比结果表明:根据塞流区边界位置与活塞速度之间的函数关系计算得到的阻尼力与实测值保持了一致,从而验证了塞流区边界位置与活塞速度之间函数关系的正确性。     

磁流变液在阻尼通道处的流变特性分析

研究了磁流变液在阻尼通道处的流变特性,利用COMSOL、Fluent软件对阻尼通道进行了流体仿真,分析了阻尼通道处磁流变液的速度、压力分布情况。结果表明:环形槽可以有效提高阻尼器的阻尼力,当深度为0.55 mm、宽度为2.2 mm,间隙为1.4 mm时,可使阻尼器的阻尼力达到最大,同时也证明了该理论模型的正确性。     

泡沫金属磁流变液阻尼器的半主动控制特性研究

设计了一种新型的泡沫金属磁流变液阻尼器。在磁场的作用下,磁流变液从泡沫金属中抽出进入到间隙,并产生可控阻尼力。针对泡沫金属磁流变阻尼器,搭建测试系统,通过激振器产生激励并施加给被控对象;采用激光位移传感器采集振动信号,采集卡将信号输入到计算机中;利用PID控制处理信号并输出电流,从而调节泡沫金属磁流变液阻尼器输出的阻尼力,控制外界结构的振动。实验结果表明,泡沫金属磁流变液阻尼器的可控阻尼性能良好,进一步验证了泡沫金属磁流变液阻尼器的半主动控制效果。     

高冲击下电流变阻尼器多物理场建模与仿真

针对将电流变阻尼器应用于冲击载荷下的火炮反后坐装置,阻尼器采用固定电极板式结构,利用COMSOL Multiphysics多物理场软件,建立电流变阻尼器的二维轴对称几何模型,根据计算流体动力学模块,得到不可压缩的电流变流体层流仿真。分析高速冲击下电流变流体在环形间隙的流动情况,并且在变化的电场耦合作用下,仿真计算出电流变阻尼器输出阻尼力的大小,同时也研究阻尼器结构参数对输出阻尼力的影响。仿真结果表明:在1~5 k V范围内增加极板电压,环形通道流体速度降低1.03 m/s,总输出阻尼力提高375.9 N;在电场强度为5 k V/mm情况下,阻尼通道有效长度增加25mm,阻尼力由828.2 N增大至1 950.8 N;保持阻尼通道长度不变,环形间隙增大1.5 mm,阻尼力下降至113.3 N。     

温度对磁流变液阻尼器力学性能的影响

设计并搭建一套磁流变液阻尼器力学性能测试系统,用该测试系统对所制作的磁流变阻尼器的力学性能进行实验研究。利用LabVIEW编写数据采集平台对温度和压力传感器的电压信号进行采集,并利用MATLAB对数据进行分析。探究磁流变液阻尼器在不同温度下施加不同电流时的阻尼力特性,并初步探讨磁流变液的黏温性能。实验结果表明:磁流变液阻尼器输出阻尼力在20～40℃之间受温度的影响较大,且随着温度的升高,阻尼力呈下降趋势。     

磁流变阻尼器的多目标优化设计与实验研究

针对现有磁流变阻尼器功耗大、输出阻尼力低的问题，以磁流变阻尼器的低功耗化及轻量化为优化目标，建立磁流变阻尼器结构参数与优化目标之间的关系模型；采用多目标遗传算法对其结构参数进行优化，得出最优解；对优化后的磁流变阻尼器进行试验研究，验证所选参数的合理性。研究结果表明：优化后磁流变阻尼器的平均功耗降低了46%、最大阻尼力增加了30%；磁流变阻尼器的功耗与阻尼力之间存在相互平衡关系，为磁流变阻尼器的参数设计提供了理论和实验依据。     

冲击载荷下磁流变阻尼器控制系统仿真研究

应用于火炮反后坐装置中的磁流变阻尼器可代替制退机提供后坐阻力.为得到理想的后坐阻力动态特性,要求其阻尼力控制系统响应快速,以实现阻尼力的输出跟踪控制.对所设计长行程磁流变阻尼器进行了冲击试验,测试其输出阻力的动态响应时间.由于试验结果并不理想,因此利用非线性逆系统方法对磁流变阻尼器跟踪控制系统进行了设计校正.最后,对校正后的磁流变阻尼器控制系统及后坐阻力动态特性进行了仿真分析,结果表明,改进设计后的磁流变阻尼器控制系统具有良好的跟踪性能,后坐阻力动态特性令人满意.     

垂直磁场圆孔型阻尼器的实验研究

根据磁流变液的流变特性，设计了一种垂直磁场圆孔型阻尼器，其外加磁场方向垂直于磁流变液的流动方向。对该阻尼器的阻尼特性进行了实验研究，测试了阻尼力与外加磁场、振幅、频率的关系，收到了良好的实验效果。如果不加磁场，又可以作为普通流体阻尼器使用。     

磁流变阻尼器的力学模型

利用磁流变液制成的磁流变阻尼器具有相应速度快、阻尼连续可调、功耗小、阻尼力大、动态范围广、频响高、适应面大等特点，本文从参数建模和非参数建模两个方面对磁流变阻尼器的力学模型进行讨论分析，着重对8种参数模型进行了分析，指出不同的设计应采用不同的模型方案，以发挥各自的优势。     

磁流变阻尼器非线性动力学行为的实验研究

磁流变阻尼器具有阻尼力大范围高度可控且耗能功率小的优点,在结构的半主动控制中有广泛的应用。磁流变流体及其元器件的动力学行为因其磁流变现象而存在滞回效应,对这种滞回效应的研究是其相关应用的基础。对磁流变阻尼器在多种激励电流与加载频率下的滞回动力学行为进行了实验研究,并进行了数学建模与参数识别。结果表明:磁流变阻尼器的阻尼力大小由激励电流控制,其非线性滞回特性具有频率依赖性;实验数据与模型仿真值的比较显示,模型可以准确模拟磁流变阻尼器滞回阻尼特性。     

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