飞机液压系统低温研究

以某飞机液压系统为对象,研究液压系统工作介质在低温环境下对系统性能的影响。在AMESim平台上建立液压系统模型,仿真不同温度下液压油黏度对液压系统性能的影响。通过仿真分析及优化,提出系统改进方案,并进行系统性能试验。试验结果验证了仿真模型的正确性及改进方案的可行性。     

基于AMESim的某型飞机液压系统仿真研究

以某型飞机液压系统为研究对象,采用AMESim4.0通用液压分析软件对液压系统建模仿真.分析了液压系统改装前后系统压力及动作筒行程的变化.该文的仿真曲线与真实的液压系统工作曲线基本吻合,从而证明了建模的合理性,所进行的数字仿真也为飞机液压系统的改进提供了一定的理论依据.     

液气锤液压系统的数学建模及仿真研究

针对沈阳某厂40 tm液气锤的液压系统进行了改进,改用大流量插装阀集成的液压系统,并对此系统打击完成后回程的工作过程进行了分析.根据液压系统工作原理建造液气锤液压系统打击后回程过程拓扑结构流程图,应用“灰箱”建模法对液气锤液压系统动态特性建立了数学模型.基于AMEsim仿真软件建立了系统模型,并得出了仿真结果,为系统改进提供了理论依据,也为今后设计锻造设备液压系统提供理论上的补充和指导.     

飞机垃圾接收车液压系统的改进

介绍国内机场普遍使用的飞机垃圾接收车的现状;根据使用过程中出现的问题,对接收车的液压系统进行了故障分析,并对整车的液压系统进行了改进,然后对改进后的液压系统进行仿真,验证了改进的效果。     

应用计算机仿真技术改进地下液压破管机系统设计

阐述了地下液压破管机系统的工作原理。应用液压系统仿真软件对该系统作出了动态仿真、分析和行之有效的设计改进。     

推移机构液压控制系统设计及动态特性仿真研究

分析推移机构液压系统的工作原理,在此基础上设计了推移机构液压控制系统。根据液压原理图,介绍推移机构液压控制系统的工作过程及主要执行部件。在AMSim中建立分析模型,运行仿真得到液压系统的动态特性。依据仿真结果,提出改进现有系统动态性能的措施,弥补了原有设计的不足。     

新型开槽机液压系统的动态特性仿真研究

在分析了新型开槽机原有液压系统存在的问题的基础上,指出了运用数字仿真法对其进行改进的必要性。采用新的建模方法———功率键合图法,建立了开槽机送料液压系统的动态数学模型,并用MATLAB软件对其进行了动态特性数字仿真研究。分析了各种技术参数对系统动态特性的影响规律,确立了改进后的送料液压系统。     

掘进机电液比例摆动控制仿真研究

基于对AM-50掘进机悬臂摆动液压控制系统的分析，提出了电液比例改进方案，对改进后的悬臂摆动液压控制系统建立了数学模型，利用Matlab软件对该系统进行了开环控制与PID控制仿真分析。仿真结果表明，该系统具有良好的控制特性。     

基于AMESim的起重机伸缩臂液压系统节能优化设计

针对随车起重机伸缩臂液压系统中存在的能耗损失大、液压系统效率不高等问题,利用AMESim等软件对随车起重机伸缩臂液压系统进行仿真研究,并根据结果提出相应的改进措施,以达到大吨位随车起重机液压系统的节能目的,对液压系统的能耗应用和AMESim仿真具有借鉴意义。     

断带抓捕液压系统的液压冲击研究

考虑断带抓捕液压系统的冲击问题,通过引入溢流阀改进原有的全断面楔形断带抓捕液压系统,描述整个系统的工作原理,基于AMESim软件建立系统仿真模型并进行仿真分析,得到楔形断带抓捕系统在抓捕状态下的液压缸活塞速度和位移动态性能曲线。结果表明:溢流阀的引入使活塞运行一半行程时活塞做减速运动,当活塞位移达到最大值3.0 m时速度降为0。改进的楔形断带抓捕液压系统减小了液压缸末端的液压冲击。     

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。