橡胶O形圈密封结构老化状态的模态分析

为避免机械装置因橡胶O形圈老化而导致的失效与故障问题，研究橡胶密封结构老化状态的无损、在线、定量检测方法是工程实际的迫切需要。基于ANSYS软件建立了橡胶O形圈密封结构的有限元模型，使用输入不同参数的方法达到了等效模型不同老化状态的目的，完成了压缩率为20%情况下的橡胶O形圈密封结构老化状态模态分析，建立了老化状态和固有频率之间的变化关系。研究结果表明：建立的有限元模型能够反映橡胶O形圈密封结构老化状态特性的变化情况，为研究橡胶密封结构老化状态的无损、在线、定量检测方法提供了先验性知识。     

基于薄板搭接的互感式焊缝跟踪传感器的分析

采用双矩形截面圆柱线圈互感式传感器作为焊缝跟踪传感器,实现了薄板搭接的焊缝跟踪.利用等效圆形回路法计算了轴线相交的矩形截面圆柱线圈之间的互感系数.使用Ansys有限元分析软件,建立了传感器的三维模型,对传感器线圈的参数进行了优化设计,分析了线圈轴线夹角对于传感器输出的影响,确定了适合于焊缝跟踪的互感式传感器结构.最后进行了互感式焊缝跟踪传感器的焊缝跟踪具体试验,传感器输出线性度良好,跟踪精度达到要求,为薄板搭接的自动焊缝跟踪技术提供了新的方法.     

零件小孔感应淬火工艺研究

研究了零件Ф8 mm小孔感应淬火工艺,包括设备选型、感应线圈和导磁体制作、零件定位夹具设计。结果表明:选用晶体管加热电源和通用数控淬火机床,磨制圆棒型导磁体,制作适当的线圈和定位夹具,采用合适的工艺参数,硬度达到技术要求。该方法操作简单、质量稳定,适合于批量生产。     

高精度数控螺纹橡胶轧辊磨床简介

介绍了一种高精度数控螺纹橡胶轧辊磨床的基本布局和主要参数,对有关橡胶材料磨削的特殊部件的结构、橡胶材料螺纹的测量原理和磨削工艺等进行了重点介绍。     

橡胶O形圈密封结构老化状态的随机振动分析

为研究橡胶密封结构老化状态的无损、在线、定量检测方法，基于有限元法建立橡胶O形圈密封结构的有限元模型，使用输入材料参数的方式达到了等效模型不同老化状态的目的，通过模态分析总结固有频率与老化状态间的变化规律，采用脉冲激励试验证明有限元模型的正确性。随后，基于模态分析完成了压缩率为14.3%的随机振动分析，总结了响应功率谱与老化状态间的变化规律。研究结果表明：建立的有限元模型能揭示结构老化状态响应特性的变化情况，为研究其老化状态的无损、在线、定量检测方法提供了先验性知识。     

传导冷却无绝缘高温超导二极磁体的研制

本文研制了一台中心磁场为1.5T的传导冷却型的无绝缘高温超导二极磁体,它主要由常温铁芯、高温超导双饼线圈以及低温恒温器等组成。铁芯的极头采用圆柱形结构,极头之间的距离为120mm。其中,每个线圈匝数为176匝,磁体的运行电流为286A。线圈冷体由一台GM制冷机进行冷却,运行温度小于20K。本文主要介绍高温超导磁体的设计以及所使用高温超导带材的载流性能,并对无绝缘线圈在装入铁芯前和装入铁芯后的充电和放电特性进行了测试研究。通过测试得到了该磁体充电延迟时间常数,并且测试结果表明,在励磁电流为286A时,中心磁场强度达到了设计要求。     

回火对金属橡胶材料疲劳特性影响分析

对回火和未回火圆盘形金属橡胶试件进行了疲劳加载试验。通过割线刚度和等效粘性阻尼系数两个疲劳损伤参数对金属橡胶材料的承载能力和阻尼耗能能力进行了分析。结果表明:回火处理有助于消除金属丝线的应力,稳定试件尺寸,可以在较大程度上提高其承载和耗能能力,并延长其疲劳寿命。     

散热环境对高温超导带材失超传播速度的影响

对Bi2223/Ag高温超导带材在制冷机环境下的失超传播特性进行测量,主要研究横向散热介质对纵向失超传播速度的影响。在样品带材的两个侧面贴敷不同的散热介质,由热电偶监测样品带在不同传输电流和工作温度时的失超温度轨迹,进而得到超导带材的纵向失超传播速度变化规律。结果表明,超导带材的横向散热环境越好,纵向失超传播速度越慢,通过改善超导体横向散热结构可以大幅提高超导体稳定性。这对超导磁体的饼式线圈设计和高温超导体的稳定性研究有重要意义。     

1.5T MgB_2超导实验磁体的设计和研制

采用Fe、Ni复合基底、矩形截面的MgB2超导带材,设计了一个孔径为100mm的实验磁体,以该磁体为基础,进行了中心磁场可达1.5T的制冷机传导冷却MgB2超导MRI磁体系统研究,提出了采用MgB2超导接头制作持续电流开关及改善磁体温度均匀性的技术途径,绕制并实验了其中心螺管线圈,该线圈在105A工作电流下,产生的中心磁场为0.74T。     

基于斜螺线管型超导Gantry二极磁体设计

为了解决当前Gantry治疗装置面临的难题—磁体重量庞大,运行成本昂贵,本文提出了一种新型的斜螺线管型线圈结构。目前,我们已经完成了一台2.5 T用于重离子Gantry的NbTi超导磁体样机设计,与质子Gantry相比,其有效缩减了磁体的尺寸和重量。该磁体由10层斜螺线管线圈组成,工作电流为1000A。线圈孔径为176mm,其中好场区达到孔径的2/3。由于线圈形状的特殊性,其端部结构无需优化,各高阶谐波量沿轴向积分为零。磁体采用传导冷却的方式,保证其在旋转的情况下安全稳定运行。本文从斜螺线管线圈的概念出发,详细介绍斜螺线管型超导二极磁体的磁场设计,借助于ANSYS有限元分析软件,仿真了超导磁体和冷屏的空间温度场,得到磁体低温系统的热分布,最后简要介绍磁体的加工情况。     

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。