旋转型行波超声电机定转子机电耦合有限元分析

以旋转型行波超声电机定转子为研究对象,运用动态子结构法和有限元法对定转子进行了机电耦合分析,构建了机电耦合模型,并通过建立定转子机电耦合有限元模型,对压电陶瓷逆压电效应进行研究,得到电信号激励下各阶响应振型和幅频特性;探讨了定子弹性体厚度、齿深,压电陶瓷片厚度、分区方式以及定子弹性体与压电陶瓷片粘接位置对超声电机谐振频率和振幅的影响,为该类型电机的结构优化设计提供了依据。     

压电驱动精密流量阀流场分析

为实现对流量的精密控制,利用压电陶瓷的逆压电效应来驱动阀芯运动,建立压电陶瓷驱动精密流量阀和内部流场三维模型,利用Fluent软件分析了阀内部的流场特性,取得了阀稳态时的内部压力场、速度场的分布规律和内部流体的迹线规律。分析结果表明:阀芯节流口处压力损失较大,并形成局部负压,流体在此处速度达到最大且以喷射流形式流入低压腔,阀芯与阀体接触处应采用抗冲刷及高强度材料;阀出口处进行倒圆角处理,可有效消除负压并使流体迹线稳定。     

超声行波马达环形定子的振动模式

利用傅立叶变换对由环形压电陶瓷片激励的超声行波马达环形定子的振动模式作了分析,说明了在保持为某一振动模式设计的压电陶瓷片塗银电极图形不变的情形下,改变激励电源的频率到某些值时,也能激发起其它一些的振动模式.并实验验证了部分结果.     

基于压电驱动的数字化微喷射技术的研究

介绍了一种基于压电驱动的数字化微喷射技术。利用逆压电效应,对压电驱动器施加周期性电场,使与之固连的微管道固壁产生周期性运动,固壁边界层内的流体随管壁一起运动,并通过粘性力将运动传递,带动微管内部流体一起运动,实现了微流体的驱动。以粘性不可压缩流体运动的纳维-斯托克斯方程为基础,得到了压电驱动微管道内流体的运动控制方程及其解;在此基础上分析了形成微喷射的原理。对微喷射进行了实验研究,喷出的液体量微小、可控,且适用不同流体的喷射。     

无铅压电陶瓷及其应用研究

随着社会可持续发展战略的实施和人们环境意识的加强，无铅压电陶瓷及其应用已成为了当前铁电压电材料及其应用研究的热点。本文根据近期国内外有关无铅压电陶瓷的发展，结合本课题组肖定全教授等近年在无铅压电陶瓷的研究，对无铅压电陶瓷的研究进展及应用现状进行了综述，重点介绍了BaTiO3基、Bi1／2Na1／2TiO3基、碱金属铌酸盐基、钨青铜结构和铋层状结构五大体系无铅压电陶瓷的性能、本课题组主要发明的无铅压电陶瓷体系以及BNT基无铅压电陶瓷在滤波器上的应用和发展前景。     

高性能压电材料制备技术及其应用

本项目在研究压电材料各向异性和微结构相图基础上,针对钙钛矿结构压电陶瓷和有机压电聚合物,采用独特工艺,制备了高性能低成本压电陶瓷,实现了新型陶瓷成分设计、微结构表征和性能优化;结合第一性原理密度泛函方法,建立了高性能有机压电聚合物的组织设计、结构调控、性能分析的理论和准则。该制各技术获国家发明专利2项。     

微驱动电极进给机构的设计

根据微细电火花加工对伺服进给系统的要求,以蠕动式进给机构作为微驱动机构,以实现高精度高频响。详细分析了柔性铰链及压电陶瓷的原理和特点,指出压电陶瓷-柔性铰链机构在微进给中具有高响应频率、高精度和无间隙等优点。在此基础上,将压电陶瓷与整体式柔性铰链相结合,设计出一种能满足微细电火花加工要求的压电驱动蠕动式微进给机构。     

气中连续放电辅助加工中的控制系统设计

以压电陶瓷微位移驱动原理为基础，对精密驱动技术在气中连续放电辅助加工控制系统中的应用进行了研究。设计了一个包括单片机、压电陶瓷驱动电源、信号检测及处理电路组成的气中连续放电辅助加工控制系统。该系统能根据加工时两电极间电压的变化自动寻找最佳放电间隙，并维持辅助加工中的连续放电,可应用于一些高硬度、难切削材料的辅助加工领域。     

纳米电机Nanomotion推出

根据压电陶瓷所具有的超声波驻波原理，Nanomotion推出了极为先进的电机。它的工作方式和直线伺服电机类似，但却具有压电执行机构特有的高分辨率和动态性能。它结构紧凑，没有行程限制，对于直线运动和圆周运动具有无可匹敌的精度。     

压电陶瓷传感器二维微量进给机构的试验研究

通过试验对压电陶瓷传感器（PZT）驱动的二维微量进给机构进行了研究，并给出了压电陶瓷传感器驱动电源及微量进给机构的设计方案和性能。切削实验表明，采用二维微量进给机构能有效提高加工精度。     

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。