同侧两轴连通式油气悬架系统研究

为改善车辆的振动性能,提出车身同侧的两轴连通式油气悬架。介绍了同侧两轴连通式油气悬架的结构和工作原理,并在此基础上建立了其数学模型;对悬架系统的刚性特性和阻尼特性进行了研究,分析了系统的连通特性,并研究了系统参数对悬架性能的影响;分析了悬架系统对激励的响应机制。研究结果表明:相对于独立式悬架系统,同侧两轴连通式悬架系统具有振动更平稳,恢复平衡状态更快,更有利于快速通过复杂路面等优点;同侧两轴连通式悬架的阻尼力不具有连通性,且其大小是由多因素共同决定的;外界激励的频率主要影响悬架的阻尼力,相位差主要影响悬架的刚性力。     

基于AMESim的传统悬架与油气悬架性能对比分析研究

基于AMESim软件建立了1/4车辆传统悬架与油气悬架模型,并基于积分白噪声法建立C级路面不平度模型,通过仿真实验对比分析传统悬架与油气悬架簧上质量与簧下质量垂向振动位移、速度、加速度及加速度均方根值等性能。结果表明:油气悬架较"弹簧+阻尼减振器"结构的传统悬架具有更好的减振效果,能够进一步改善车辆行驶平顺性,为油气悬架车辆行驶平顺性性能改善及设计提供理论指导。     

单气室油气弹簧阻尼特性分析

针对单气室油气弹簧阻尼特性问题,基于薄壁小孔理论和海根-波斯勒公式分别建立了两种阻尼结构的油气弹簧系统阻尼力的数学模型。利用Matlab Simulink软件仿真,研究了油气弹簧系统结构参数和激励参数的变化对其阻尼性能的影响。研究结果表明,油气弹簧系统示功图所围面积随激励参数和环形腔E面积增大而增大,而随阻尼孔节流面积增大而减小;外界激励参数的改变对系统速度特性曲线基本没影响;速度特性的非线性揭示了油气弹簧系统阻尼的非线性。研究结果可以为类似结构设计提供参考。     

基于Simulink的油气特性对油气悬架性能影响分析

油气悬架的特性是由内及外的,内部物质的状态很大程度上决定了悬挂对外界输入的响应。基于油气悬架的结构特点,考虑气体在油液中的溶解和掺混、油液经小孔节流产生的气体和密封圈的摩擦力,建立油气悬架非线性数学模型。基于Simulink搭建分析模型,对油气悬架工作过程进行分析,对不同频率激励的响应、气体压力变化进行对比分析,并对单向阀阻尼孔参数的改变及气体溶解于油液的特性对油气悬架外特性的影响进行分析。分析结果可知:单向阀尺寸的改变对油气悬架在持续正弦激励下的外特性影响较小,而阻尼孔的尺寸对其影响较大;气体溶解于油液的特性会影响油气悬架的外特性,油气不分离式油气悬架的溶解特性可以降低悬架输出力的振动幅度,使得悬架内部状态更平稳,有效提高整个系统的可靠性。     

集成缓冲装置的电静压作动器阻尼特性研究

针对挂架投放机构的稳定作动需要,提出电静压作动系统方案,设计端部闭式缓冲结构结合节流阀的复合阻尼调节方案,建立复合阻尼系统的数学模型,仿真分析投放机构投放物体过程中,复合阻尼结构参数对作动器位移、速度、阻尼力的影响。结果表明：作动器到位缓冲能力与电磁阀及节流阀的节流孔大小成正比,缓冲结构的环形缝隙的偏心程度及闭式容腔的体积对作动器的阻尼性能影响较大,环形缝隙主要影响阻尼力二次峰值,闭式容腔的体积主要影响阻尼力的过程累积能量转化量。     

一种液压阻尼器的结构及阻尼性能分析

介绍了一种在石油井下工具上使用的液压阻尼器的结构与工作原理,对该阻尼器的阻尼性能进行了分析,得出了阻尼性能的计算公式.分析表明,阻尼效果随节流孔直径增大而降低,且节流孔直径越大,阻尼效果降低越显著;阻尼效果随阻尼孔板数量的增多而增大,但孔板数越多,对阻尼效果增大的影响变小.阻尼力的大小与活塞面积、恢复弹簧的刚度和压缩量等参数有关,可以通过改变弹簧的性能,获得需要的阻尼力.该类型的液压阻尼器已在石油井下工具中应用,效果良好.     

非公路车辆油气悬架振动特性的台架试验

利用半实物仿真台架,通过改变油气悬架系统中可调阻尼阀的阀芯转角、蓄能器内氮气的初始体积、激振台正弦激励的频率和幅值,得到了各参数对簧上质量、簧下质量的加速度均方根值和车轮动载荷等振动特性的影响曲线。实验结果表明:簧上质量的振动加速度比簧下质量滞后1/2个周期,安装油气悬架能显著改善非公路车辆动力学性能。     

基于AMESim的重型车辆油气悬架振动特性仿真研究

介绍一种重型车辆油气弹簧的结构,建立油气悬架系统的非线性阻尼数学模型和单轮两自由度振动数学模型.在此基础上,应用AMESim软件建立油气悬架系统的单轮两自由度仿真模型,分析阻尼孔过流面积的变化对车身振动的影响.结果表明:阻尼孔过流面积的大小与车身振动的衰减与冲击关系极为密切,设计出合理的阻尼孔直径,能有效地保持行车的平...     

组合机床调速系统的计算机模拟与动特性分析

一、数学模型的建立为简化数学模型,提出以下假设:(1)不考虑管道动特性对系统特性的影响;(2)不考虑阀腔内油的压缩性;(8)不计液压缸中的液感;(4)不计系统各部的泄漏。主要符号表,风—油液的等效体积模量,Kq—流量增益,p—油液密度多l—长度;必—节流口处射流角;L—液感;A—面积;M—等效质量;b—粘性阻尼系数;断—阀芯质量,B—等效阻尼系数,m:—弹簧质量;c—流量系数;P—压力,C—液容;Q—流量;F—力,R—液阻;k—弹簧刚度;K—等效刚度多K,—压力一流量系数;下角标符号所代表的元件如下:b—背压阀;11—液压缸无杆腔;12—液压缸有杆腔;P—…     

集成式油气悬架建模及车辆振动仿真

根据油气悬架的2种构型分类,说明集成式油气悬架的优势和构造。基于基本假设,通过分析流量与运动量关系、阻尼孔压力与流量关系、管路压力与流量关系和各腔气体压力,推导出集成式油气悬架动态力的显式数学表达。采用滤波白噪声法描述车轮随机路面激励。应用车身和车轮两自由度模型建立集成式油气悬架车辆模型,确定振动响应量。在常用的B级路面和车速60 km/h条件下,对某集成式油气悬架车辆的振动进行仿真。结果表明：所建立的集成式油气悬架及其车辆模型用于车辆的振动仿真是有效的、可行的。     

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。