基于Automation Studio铲运机转向液压系统设计

以ACY-6型地下铲运机液压转向系统为研究对象,该系统采用铰接液压转向系统,转向液压系统与工作液压系统采用双泵合流技术,分析该系统的工作原理,并对动作执行机构及所受载荷进行分析,在此基础上,应用Automation Studio仿真软件搭建转向液压系统机械-液压耦合仿真模型,对系统动态工作过程进行仿真,获取了原地转向工况下转向系统与执行机构的特性曲线,为实现该种车辆液压转向系统的优化设计获得理论参考和技术支撑,具有一定的工程应用价值。     

轧机液压厚度控制系统的定量反馈优化设计

结合某2 500 mm中厚板精轧厚度控制系统设计项目,根据实际设备条件,确定合理的轧机液压伺服控制系统模型.考虑执行机构的性能与轧机系统整体稳定性的折衷问题,在PID控制器基础上,设计液压伺服定量反馈QFT控制器.综合分析执行机构的不确定性范围和系统性能指标的要求,实现了轧机液压伺服系统鲁棒控制器的设计.对比仿真结果表明:QFT调整方案能够有效保证系统的稳定性,同时具有较好的控制性能.     

拔秆粉碎机液压系统流量分配特性仿真分析

为了合理分配拔秆粉碎机多个执行机构的流量,提出基于压力补偿原理的多执行机构流量分配方法,并对液压系统的流量分配特性进行了仿真分析。首先,针对拔秆粉碎机执行机构的特点,设计了定差减压阀与梭阀相配合的压力补偿回路,并对此流量分配方法进行了理论研究,然后,采用AMESim建立仿真模型,对液压系统的流量分配和抗流量饱和能力进行了分析。结果表明,该流量分配方法能够在负载大小不同的条件下实现有效的流量分配,具有良好的抗流量饱和能力。     

无凸轮内燃机伺服压电液压执行机构及其控制研究

为解决大部分可变气门控制器无法实现气门的完全可变性,提出一种包含压电和液压部件的伺服压电液压执行机构。采用自适应前馈控制器实现伺服压电液压执行机构的有效控制。构造伺服压电液压执行机构模型,建立伺服压电液压执行机构中压电结构、伺服活塞结构和液压结构的数学模型。设计一种包含2个前馈控制器和1个反馈控制器的自适应前馈控制器。采用MATLAB软件对伺服压电液压执行机构进行仿真,并与传统PI控制器的控制结果进行对比。结果表明:采用自适应前馈控制器的伺服压电液压执行机构的跟踪性能明显提高,跟踪误差减少约50%,控制电压范围也大大减小。该执行机构能很好地实现无凸轮内燃机气门的有效控制。     

基于回流能量调节的液压执行机构运动位移控制仿真研究

为提高液压执行机构控制系统响应速度,从而降低执行机构运动位移输出误差,采用超螺旋滑模控制器,并进行仿真验证。建立回流能量调节的液压执行机构简图,定义差动阀液压流量数学模型,推导出液压执行机构动力学方程式。针对传统滑模控制器进行改进,提出超螺旋滑模控制器。给出液压执行机构超螺旋滑模控制的流程,并分析控制系统的稳定性。为进一步验证超螺旋滑模控制器输出精度,采用MATLAB软件对液压执行机构运动位移进行仿真,并且与传统滑模控制器进行对比。结果表明：采用传统滑模控制器,在空载状态下,液压执行机构运动位移与期望值偏差较小,但是在负载状态下,其偏差较大;采用超螺旋滑模控制器,在空载或者负载状态下,液压执行机构运动位移与期望值偏差都较小,执行机构反应速度较快。采用超螺旋滑模控制器,可以有效降低液压执行机构滑模控制器的抖动幅度,提高运动精度。     

基于AMESim的复合轮式海底车液压驱动系统建模与仿真

以复合轮式海底车液压驱动系统为研究对象,利用AMESim软件建立海底车液压驱动系统仿真模型,模拟深海环境下海底车越障的各种极限工况,通过设置主要系统参数,实现海底车液压驱动系统的动力学仿真。仿真结果表明:液压驱动系统及各液压元件在深海各种越障工况下安全可靠,系统稳定性好,为海底车液压系统的性能评估和优化设计提供了一条新途径。     

可变几何涡轮增压器液控执行机构的建模与仿真

简要介绍可变几何涡轮增压器的结构组成和工作原理,分析作为涡轮增压器核心部件的液控执行机构对涡轮增压器性能的影响。基于液控执行机构工作原理建立该液控执行机构的数学模型,利用Simulink仿真平台对该液压控制系统进行数字仿真,得出该液控系统的时域指标,并分析各结构参数对液控执行机构性能的影响。     

转速感应控制与负载独立流量分配的设计与应用

当运梁车行走液压系统采用转速感应阀控制时,发动机低转速会使负载敏感系统流量不饱和,从而直接导致执行机构速度受负载大小影响。针对此问题,提出使用独立流量分配系统的方法。利用AMESim软件对系统进行建模仿真,通过对比测试与仿真曲线,验证了仿真模型的准确性和系统原理的正确性。仿真结果表明:该系统能够实现发动机在不同转速下、开式液压系统的稳态响应,实现发动机和负载之间的功率匹配,对降低能源消耗具有积极意义。     

自走式蓝莓采摘机行走液压系统的设计与仿真

满足自走式蓝莓采摘机的工作性能要求,设计一种自走式蓝莓采摘机的行走液压系统。简要介绍该机的主要参数、结构、工作原理及工作流程,完成对行走系统主要元件的选型。利用AMESim软件对行走液压系统进行建模与仿真,仿真了左前轮打滑和左侧双轮打滑的两种工况。仿真结果表明：在左前轮打滑工况下,可以实现前侧流量强制分流,从而帮助采摘机脱离打滑状态;在左侧双轮打滑工况下,可以实现整机流量强制分流,从而帮助采摘机脱离打滑状态,符合设计要求,仿真结果为自走式蓝莓采摘机以及其他自走式采摘机械的行走液压系统的防打滑工况设计提供了参考。     

基于功率键合图的轮式装载机工作装置液压系统的建模与仿真

基于ZL60轮式装载机工作装置液压系统的工作原理,采用功率键合图方法建立不同工况下工作装置液压系统的功率键合图.由所建立的功率键合图列写系统动态方程,根据系统动态方程建立在铲斗后倾工况下的Simulink仿真模型.设置液压系统的仿真参数,应用Matlab/Simulink软件,编制M函数文件进行仿真.得到液压系统的性能曲线,结果有利于产品的开发改进、性能评估和优化设计.     

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。