国家严查汽车超载对金属市场的影响

据了解,国家自12月1日起再次掀起严禁公路超载的行动,与以往不同,各交通检查部门不再采用以前简单的罚款了事的办法,而是要求超载车辆立即卸货。车辆超载已是社会的一个普遍现象,经过几次国家轰轰烈烈的严查,沿路各关卡罚款剧增,汽车运输成本负担沉重,加之运输市场竞争激烈,超载现象也愈加严重,通常汽车的实际承运量均在其限定的载重量的3倍以上。汽车超载引起的车祸、路面损坏问题已令国家十分重视,此次再次严查超载事先经过了广泛宣传,在司机的心理上造成了很大压力,但我们也知道,前几次严查的结果不但是不了了之,而且车量超载更加变本加…     

发动机传动轴断裂模式分析

发动机在外场服役过程中传动轴发生断裂故障,其他多台发动机传动轴在检查中也发现了掉齿和裂纹现象。利用宏微观分析手段对传动轴的裂纹及断口进行分析研究,对其断裂模式进行模拟试验和有限元分析。结果表明:传动轴断裂性质为弯-扭复合疲劳,传动轴裂纹呈现螺旋型扩展是由于传动轴载承受正常扭转载荷下叠加了弯曲载荷,此外,弯矩的存在还改变了传动轴花键上的应力分布。     

重型货车双后桥传动轴扭转断裂的失效分析

本文对重型货车双后桥传动轴的扭转断裂进行了宏观断口、表面感应加热淬硬层与基体的金相组织、场发射扫描电镜断口形貌观察和显微硬度等分析。结果表明,不同结构传动轴的扭转断裂方式不同,其断裂原因与原材料质量、热处理工艺、微观组织以及结构形状有关。通过优化材质、热处理工艺和改进双后桥传动轴的结构设计,可以明显改善其性能指标,满足产品的技术要求。     

“十五”期间我国载货汽车需求预测

重型载货汽车“十五”期间,我国重型汽车市场需求将会有一个显著增长态势。公路和高速公路的快速发展将促进重型货车的发展和公路运输结构向重型化发展,燃油税的实施对高技术性能的重型车辆运输促进较大,对车辆超载运输的抑制也会促进重型车的需求,这一切将会对重型汽车市场的需求带来一个较好的促进。参照国外经验,货车市场改装车占货车市场需求量的50%～55%,而我国目前这一比例仅为15%～20%。改装车是货车市场需求潜在增长的产品,     

发动机曲轴摩擦转矩监控系统优化

针对人工判定发动机曲轴摩擦转矩存在可信度低的问题,文章设计了曲轴摩擦转矩的监控系统,包括设备与发动机配合的夹持适配机构、监测硬件和程序。通过对曲轴摩擦转矩进行分段监测,同时基于6 Sigma原则来设定和优化摩擦转矩监控阈值,实现对摩擦转矩的准确监测,摩擦转矩真实反映摩擦副的配合状态。通过异物试验验证优化后的摩擦转矩检测系统对异常发动机筛选的合理性和有效性。试验表明,夹持适配机构使摩擦转矩监控系统工作稳定,监测程序分为2个阶段设置,且基于6 Sigma原则来优化摩擦监控阈值能够很好满足使用要求。     

车辆轮荷动态测试系统研究

为了获取车辆行驶时车轮的动态垂直载荷,设计一种车辆轮荷动态测试系统,详细介绍该系统的硬件和软件,并在特定试验路面上进行了测试,解决了因传感器无法安装在车轮上动态获取实时车轮载荷的难题.     

在铁路货车行业推行欧洲标准EN15085"轨道车辆及其零部件的焊接"

论述了推行欧洲标准EN15085<轨道车辆及其零部件的焊接>的意义及重要性、阐述了EN15085标准涉及的内容和关联的欧洲标准、国际标准.该标准对焊接制造商的质量要求和认证、设计要求、生产要求、检验、试验与文件等方面均做出了详细规定.在铁路货车行业推行EN15085"轨道车辆及其零部件的焊接"标准,可以促使货车行业全面提升焊接结构设计水平和焊接工艺制造水平.     

在铁路货车行业推行欧洲标准ENl5085“轨道车辆及其零部件的焊接"

论述了推行欧洲标准EN15085《轨道车辆及其零部件的焊接》的意义及重要性、阐述了EN15085标准涉及的内容和关联的欧洲标准、国际标准。该标准对焊接制造商的质量要求和认证、设计要求、生产要求、检验、试验与文件等方面均做出了详细规定。在铁路货车行业推行EN15085"轨道车辆及其零部件的焊接"标准。可以促使货车行业全面提升焊接结构设计水平和焊接工艺制造水平。     

摩托车万向节的抗应力研究

万向节是正三轮摩托车传递动力的关键装置,在车辆动力传递系统中起着非常重要的作用,保证传动系统传动轴之间的夹角和距离发生变化的情况下,仍能可靠地传递动力。万向节经过处理后,它的力学性能直接影响着摩托车载货能力以及摩托车整车的安全,对摩托车整车的质量产生根本的影响。     

传动轴多工位锻造过程数值模拟及工艺优化

传动轴属于车用关键零部件,其锻造质量直接影响到车辆的行驶安全。本文利用Deform-2D软件分别对汽车传动轴锻造的两种不同工艺方案进行数值模拟,对模拟得到的应力、应变、载荷和损伤值等参数进行分析与比较;通过优化目标使挤压过程中每个工位的模具承受载荷较小、且分布均匀。模拟分析和试验验证表明,采用试验工艺的第2种方案生产出的零件无裂纹缺陷,零件表面质量好,单个工位变形量小,这种工艺方法可适用于大批量生产。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.