大流量安全阀动态性能试验台设计及仿真研究

新国家标准对液压支架用安全阀的动态性能的试验要求较旧标准多出了公称流量启溢闭特性试验,而目前大流量安全阀动态性能试验台大多只能对其冲击特性进行试验。因此,设计了以蓄能器快速加载为特点的大流量安全阀试验台,以满足新国家标准的要求,并采用了AMESim软件对试验台液压系统进行仿真,结果表明该试验系统的流量和压力曲线符合新标准要求。     

汽车用塑料燃油箱试验台的设计

阐释汽车塑料燃油箱现行主要标准的检验方法,给出了试验台设计的总体方案,设计了试验台的结构和控制电路,介绍了塑料燃油箱试验台的功能和操作过程,能够完成燃油箱盖的密封性试验、安全阀开启压力试验和耐压试验,能够模拟汽车燃油箱在实际使用时的工作状况。实际应用验证了试验台设计的正确性及其工作的稳定性,达到了预期的效果。     

液压支架用大流量安全阀试验台测试系统的设计

为了满足液压支架用大流量安全阀各主要性能参数自动测试的需求,开发了基于Lab VIEW的测试系统。目前该系统运行在大流量安全阀试验台的测试工作中,实践结果表明:该系统稳定可靠、测试效率高,在实验教学及工业性试验中均取得了一定成果。     

液压支架高压大流量阀综合试验台设计与仿真

针对液压支架高压大流量阀设计以双蓄能器组为辅助动力源的试验台,配合增压缸实现系统的分时快速加载。该试验台可为被试阀提供近乎阶跃的短时大流量高压冲击,模拟液压支架承受严重顶板冲击的工况。基于AMESim软件搭建试验系统的仿真模型,并以FAD100/40型安全阀为试验对象,进行冲击压力安全性和公称流量启溢闭特性仿真分析。结果表明：所设计的安全阀冲击安全性试验系统能在规定时间内达到国家标准规定的阀前冲击压力;公称流量启溢闭特性试验系统提供的被试阀开启压力、流量、压力上升梯度及公称流量溢流时间均满足国家标准,进一步验证了试验台及试验方法的合理性。     

大功率超高压安全阀试验台的研制

本文介绍大功率超高压安全阀试验台的液压系统的工作原理、超高压油源、设计计算及超高压状态下的安全防护等。     

新型柱塞式安全阀设计优化及仿真分析

针对导弹气路系统用安全阀小型化、大流量、高可靠性的发展要求,设计一种新型柱塞式安全阀。绘制安全阀的流场的几何模型,基于Fluent仿真分析平台建立新型柱塞式安全阀流道的数学模型。对其进行详细的流场分析,明确了安全阀气穴气蚀的产生机制和影响因素,并提出流道优化方法。利用AMESim软件分析了优化后柱塞式安全阀动态特性。最后,利用测试系统进行了安全阀的启闭特性试验,试验结果满足设计要求,验证了理论分析和设计方法的正确性。     

多功能液压试验台设计

提出了一种集泵-缸、闭式泵-马达、开式泵-马达、冷却系统于一体,可实现远程无线通信与管理的多功能液压试验台。对试验台的液压系统进行了设计,并对试验数据的检测、采集、远程监控功能进行了分析;将该试验台与传统试验台的设计进行了比较;设计并进行了闭式泵的测试实验,绘制了闭式泵的转速、压力及加载转矩变化曲线。结果表明:该试验台相比传统的更方便、快捷、先进;闭式泵-马达的试验结果符合设计要求,达到了试验台的设计要求。     

一种EHA试验台设计与研究

针对伺服直驱泵控液压系统,研制了一种EHA (电静液作动器)试验台。对试验台数据测试和数据采集系统进行了集成设计,对试验台的组成、技术要求、工作原理以及功能和控制系统进行了设计与研究。该试验台按DDVC系统试验台的要求而设计,能够实现同一试验完成多项测试的目的,具有很好的推广价值。     

直动式安全阀启闭特性分析与优化

针对某安全阀启闭特性影响无法满足设计需求的问题,需要对液流力进行分析。首先进行流场仿真与分析,研究安全阀内部流体的流动特性与液流力作用规律,得到安全阀启闭特性不足的主要原因是安全阀出口结构不合理;基于动力学分析与CFD仿真结果构建AMESim仿真模型并复现实验曲线,通过提高出口位置以及扩大出口直径实现安全阀的结构优化。结果表明该方法可以有效改善安全阀的启闭特性,使其关闭压力达到正常关闭要求。     

液压元件性能试验台控制系统的研究

液压元件性能试验台是进行液压元件质量检测的必要设备,是液压元件质量监控的保障。介绍液压元件测试试验台的系统组成、原理和特点,采用上位机控制下位机的控制方式对液压元件测试试验台控制系统进行了设计,对多试验台共用液压源的控制方法进行了研究,并提出了实用的方案。     

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).     

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.     

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.     

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。