支架搬运车闭式液压行走系统特性仿真及试验研究（英文）

用于井下煤矿生产的支架搬运车液压行走系统工况条件差、故障模糊性及随机性大、检测维修成本高且路试困难。针对此问题,首先根据A4VG型柱塞泵的机械结构及工作原理,采用参数化建模方法建立了系统联合仿真模型,分析了泵的压力流量特性及其控制回路运行特性;然后设计了系统试验台对柱塞泵及其控制回路特性进行了试验测试。结果表明:采用试验测试与仿真分析相结合的方法能有效地反映泵控回路维修结果,大大提高了维修效率,降低了成本。     

轴向柱塞泵振动噪声诊断分析与研究

对某型轴向柱塞泵的振动异响噪声原因进行了分析与研究。开展了轴向柱塞泵振动测试试验,搭建了振动测试试验台并进行多点振动功率谱测试,进行了柱塞泵的理论输出压力、流量脉动,时域、频域特性分析,以及结构件模态仿真分析。通过试验和仿真结果的对比分析,定位了泵-试验台系统的噪声来源,明确了产生原因,提出了消除噪声的方法。     

泵控液压机蓄能器快锻回路控制特性影响因素研究

针对泵控液压机蓄能器快锻回路控制特性影响因素展开研究,采用功率键合图的方法,通过Matlab/Simulink进行仿真研究,以0.6 MN泵控液压机为平台进行实验研究。搭建了液压缸、管道、蓄能器、比例变量径向柱塞泵、活动横梁的模型,得出回路的功率键合图模型,推导出Matlab/Simulink仿真模型,并在0.6 MN泵控液压机上进行了试验研究。通过仿真和实验分别研究了锻造频率、锻造行程、初始压力变化对泵控液压机蓄能器快锻回路控制特性的影响。研究结果表明:减小锻造行程,在一定范围内提高锻造频率,锻造精度提高;提高蓄能器初始压力,回路响应变快。     

虑及控制机构运动关联的柱塞泵动态特性研究

针对柱塞泵建模过程中因函数简化控制机构及其运动关系而造成的误差大、不精准问题,提出基于控制机构运动关联的非简化建模方法。结合柱塞泵的控制原理,利用AMESim搭建功率-压力-电比例复合控制的柱塞泵仿真模型。通过对压力、电流和转速的组合控制,对柱塞泵的控制特性进行仿真测试,得到与理论研究相吻合的动态特性曲线。进一步通过台架试验对柱塞泵进行测试,试验结果表明：柱塞泵在实际工作中存在响应时间,系统流量在液压系统开启和闭合瞬间存在冲击振荡。对比两种建模思想的仿真结果,非简化模型最大相对误差分别为3.51%和5.08%,平均相对误差分别为1.74%和1.98%,均小于简化模型。柱塞泵建模准确,为实现产品性能优化和系统数字孪生提供了模型支撑。     

基于AMESim液压仿真平台的双联轴向柱塞泵液压系统分析及试验研究

以挖掘机用九柱塞双联轴向柱塞泵为模型,利用AMESim液压仿真平台对泵的液压系统进行仿真分析,得到液压泵的压力、流量和效率等变量特性.根据双联泵系统特性,搭建双联泵液压系统仿真模型,分析不同负载信号下的上述各项变量特性.通过搭建的试验台进行试验验证,分析测试结果.结合仿真结果,对液压系统作出较完善仿真分析,为该泵的进一...     

电液比例斜盘式轴向变量柱塞泵的压力特性仿真

建立了电液比例斜盘式轴向变量柱塞泵的控制模型,以MATLAB/Simulink为工具,对变量柱塞泵的压力控制特性进行了仿真研究,分析了泵的关键参数对其工作特性的影响,为电液比例斜盘式轴向变量柱塞泵的设计、优化提供了简便、实用的计算机辅助设计方法.     

基于流量匹配的泵控挖掘机动臂能耗特性分析

为解决泵控非对称缸两腔所需流量不相等的问题,在轴向对称柱塞泵的基础上,提出一种能够平衡非对称缸流量差的变量非对称泵控缸闭式方案。通过控制变量非对称泵的斜盘角度实现对非对称缸的运动方向与两腔流量的控制,并将其应用于负载敏感液压挖掘机动臂回路中。为分析该方案的可行性,利用AMESim软件建立系统仿真模型。通过仿真分析,对比了变量非对称泵控系统与传统负载敏感阀控系统动臂运行特性和能耗特性。结果显示,采用变量非对称泵控系统动臂运行更加平稳,能耗降低36.9%。     

双压力柱塞泵建模与仿真研究

双压力泵源系统是机载液压系统发展方向之一。分析双压力柱塞泵的工作原理;以AMESim工程软件为平台,建立双压力柱塞泵仿真模型,对双压力柱塞泵的动态特性进行仿真分析。仿真结果符合设计要求,为机载双压力柱塞泵的优化设计提供了依据。     

液压柱塞泵流量脉动测试的试验研究

提出了液压泵流量脉动测试的实用近似方法,对液压柱塞泵流量脉动的测试技术进行了系统的试验研究。并以一台较大排量的轴向柱塞泵为被试泵,建立了流量脉动测试系统,实现了多种压力下被试泵流量脉动的测试。     

工程机械油泵特性分析及其控制机制

针对工程机械所需的高性能液压设备,分析轴向柱塞油泵运用于工程机械的可行性,深入研究直轴式轴向柱塞泵结构及工作特性,并计算了柱塞泵变量机构的排量和输出流量.研究了恒功率变量泵变量控制机制,基于单片机开发了恒功率变量泵控制系统,为高性能工程机械液压系统的设计提供了理论指导.     

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。