电液伺服阀用超磁致伸缩转换器的建模与动态仿真研究

介绍电液伺服阀用超磁致伸缩转换器(GMA)的结构和工作原理;在建立转换器数学模型的基础上,构建转换器的AMESim仿真模型,分析阻尼系数、等效质量、驱动频率和GMM棒刚度系数等不同参数对转换器动态特性和输出位移的影响。仿真结果表明:增大阻尼系数,减小等效质量,可以提高转换器的动态特性;减小驱动频率和GMM棒刚度系数,可以增加转换器的输出位移。仿真结果为电液伺服阀用超磁致伸缩转换器的结构参数优化提供了理论依据。     

超磁致伸缩驱动器及其微位移特性研究

基于超磁致伸缩材料的磁致伸缩效应,研制一种具有可控微位移功能的超磁致伸缩驱动器,并对外加预压力下该驱动器的微位移特性进行了实验研究。采用位移传感器、数据采集卡、驱动电源等,搭建超磁致伸缩驱动器的微位移性能测试台,实验研究在外加电流、预压力下,超磁致伸缩驱动器的输出位移与外加电流的关系。研究结果表明:在外加预压力为0~300 N时,驱动器的输出位移随外加电流的增加而增加;而在外加预压力为300~400 N时,超磁致伸缩驱动器的输出位移随输入电流的增大而减小。     

超磁致伸缩材料的性能测试及应用

测试了Terfenol-D磁致伸缩棒的磁致伸缩性能,并利用此性能在机械构件上推广应用。取Terfenol-D磁致伸缩棒放在测试仪上,对测试仪进行加压、通电、标定等进行初始化,然后给测试仪线圈传送变化的电流值,不同的电流会引起磁致伸缩棒周围按照一定规律变化,最后观察传送回的应变位移数据,通过这些数据进行计算、总结、图表分析。Terfenol-D磁致伸缩棒磁致伸缩系数在磁场强度增加初期增长率较小,当驱动磁场强度继续增加时,磁致伸缩系数增加得很快并且线性较好,当磁场强度再持续增加时,磁致伸缩系数增长开始变缓,并逐渐趋于饱和状态。Terfenol-D磁致伸缩棒的磁致伸缩性能优于其他材料,并可以对位移进行更加精确地控制。     

伺服阀用超磁致伸缩驱动器的相变温控研究

设计一种伺服阀用超磁致伸缩材料驱动器(GMA),采用相变材料对超磁致伸缩材料(GMM)的温度进行控制,理论分析了驱动器的热量来源及所填充的相变材料的潜热,并用ANSYS对驱动器的热特性进行研究,分析恒定电流下相变材料对GMM棒温度变化的稳定作用。     

基于超磁致伸缩致动器的再生型车削颤振抑制系统实验研究

切削颤振是金属加工时刀具和工件之间的一种复杂且有害的强烈相对振动。分析了再生型颤振的机制,建立了超磁致伸缩致动器(GMA)颤振系统的动力学模型,并阐述了超磁致伸缩微致动器颤振系统的稳定性。最后通过对比切削颤振实验和颤振抑制实验的振动信号数据结果,验证了基于GMA的颤振抑制系统抑制切削颤振的可行性。     

基于GMA再生型车削颤振抑制系统实验研究

切削颤振是金属加工时刀具和工件之间的一种复杂且有害的强烈相对振动。文章从理论上分析了再生型颤振的机理,建立超磁致伸缩致动器( GMA)颤振系统动力学模型,并阐述了超磁致伸缩微致动器颤振系统的稳定性,最终通过对比切削颤振实验和颤振抑制实验的振动信号数据结果,验证了基于GMA的颤振抑制系统抑制切削颤振的可行性。     

基于超磁致伸缩驱动的输液泵设计及可行性研究

针对传统机械式输液泵的输液精度低、输液不平稳等问题,提出一种基于超磁致伸缩微驱动的输液泵的概念设计。介绍该新型输液泵概念结构和工作原理;对输液泵的超磁致伸缩驱动器装置进行初步的可行性研究。结果表明:在外加电流为0～2 A时,超磁致伸缩驱动器的输出力达到470 N、输出位移达到58μm,可控性能优异,验证了超磁致伸缩微驱动输液泵设计的可行性。     

多Terfenol—D棒磁致伸缩作动器结构优化设计

设计了一种包含3根Terfenol-D棒的磁致伸缩作动器,并根据电磁学原理,在对磁致伸缩作动器内部磁路分析的基础上推导出了作动器输出位移与Terfenol-D棒的长度以及上下端盖的尺寸之间的关系,以此为根据对作动器进行结构优化以使其结构更加紧凑.通过ANSYS仿真表明:由于螺线管和上下端盖组成了闭合磁路,大大改善了螺线管端部的磁场分布情况,同时由于采用热膨胀抵消补偿法克服了温度对作动器输出位移的影响,从而最大限度地消除了作动器输出的非线性.     

基于超磁致伸缩执行器等效电路的自感知方法研究

为了使超磁致伸缩执行器(GMA)同时作为执行器和传感器,可以在GMA驱动过程中提取出感知信号实现自感知执行器.分析了超磁致伸缩自感知机理,以此设计了直动型GMA,并利用压磁方程和弹性力学建立了直动型GMA的动力学等效电路模型,在此基础上,提出了优化GMA结构设计的准则,并将力学量转化为电学量,通过测量电流i来实现输出力与速度的感知.最后,在研制的基于labview的测控平台系统上,验证了上述力与速度感知方法的有效性.     

相变温控及其在超磁致伸缩致动器中的应用

文章分析了超磁致伸缩致动器的热特性,提出了采用相变材料控制超磁致伸缩棒温升的抑制方法。试验结果表明相变温控装置能将超磁致伸缩棒的温度控制在45±0．5℃,此时因工作温度变化引起的位移输出误差不超过0．1μm,超磁致伸缩致动器相应的输出精度达到0．5μm。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。