门式框架动态特性的有限元分析

本文利用C0SMOS/Works有限元分析软件，对FMC—MJ460柔性加工单元中的门式框架进行了动态特性的有限元分析。透视分析结果，可为门式框架的动态设计提供科学依据。     

压力机门式机身有限元分析与校核方法

在机床改型设计阶段,机身作为主要的零部件,对其强度、刚度的校核非常有必要。依据长期的有限元分析经验,本文以我公司JM36-250机身为例,详细给出了用于门式机身有限元校核的分析方法与相关校核标准。该校核方法及标准,在近两年的生产实践中证明是合理、可行的。     

水电站门式起重机的发展趋势

论述门式起重机的使用前景，发展趋势，主要结构及一些重要零部件的设计改进技术，分析其发展与变化，门式起重机的发展是与水电站的发展同步，由设计思想和设计方法的进步所带动，由经济基础来推动。     

基于BIM-Tekla的钢结构框架梁柱焊接接头残余应力有限元分析

为提升钢结构框架梁柱焊接接头残余应力有限元分析的全面性,提出基于BIM-Tekla的钢结构框架梁柱焊接接头残余应力有限元分析。该方法首先对钢结构框架梁柱有限元建模时的热应力、生热率及屈服强度等参数进行计算;基于BIM-Tekla平台,完成钢结构框架梁柱焊接接头有限元模型的建立;根据建立的有限元模型,确定梁柱焊接接头残余应力值与不同温度、位置、角度、路径、材料参数之间的关系,获取钢结构框架梁柱不同焊接接头残余应力值分布,从而实现对钢结构框架梁柱焊接接头残余应力的有限元分析。试验结果表明,梁柱的焊接接头残余应力值随着板材梁翼缘厚度增大而不断缩减,而钢结构框架梁的焊接接头残余应力值则随着板材梁翼缘厚度增大而不断增大;当焊接接头坡口角度为60°～210°时,残余应力值分布较为均匀,无明显波动变化,而在210°～360°时,接头的残余应力波动幅度较大;焊接接头的残余应力受框架直径比值影响较大。     

32/10 t-15 m门式起重机主体结构设计分析

对32/10 t-15 m门式起重机整机稳定性进行计算,并建立三维模型。基于静态设计-动态补偿计算方法应用Workbench有限元分析软件,对两种危险工况下的起重机主体结构进行受力分析,得到各部分应力云图和变形云图,对该起重机结构的设计方案进行验证,为起重机总体设计提供了可靠依据。     

基于有限元法的燃料电池发动机主框架静力学校核与模态分析

文章建立了一种燃料电池发动机主框架的有限元实体模型，应用有限元法对其进行了静力学分析，分别获得了发动机主框架在承受一定静载荷条件下各节点的变形情况与应力分布情况，在此基础上，应用分块Lanczos法对该发动机主框架进行了模态分析，得到了其低阶固有频率及其对应的振型和振型动画。上述校核与分析不仅满足了实际工程设计需要，而且为燃料电池发动机的结构优化以及进一步深入的动力学分析提供了理论依据。     

《中国重型装备》总第95～98期目次

篇名年—期·设计·300 MN模锻水压机机架的有限元模态分析2008—1……………………………………………1 100 mm平整机组的研制……………2008—1门式起重机柔性体的建模方法研究……2008—1高速高精度数控机床的轨迹控制………2008—1大型金相试样切割机控制系统的设计2008—1     

拉矫机基础框架的优化设计

利用FEA软件对拉矫机基础框架有限元模型进行仿真分析。针对原设计存在的问题进行了优化改进,使新设计的基础框架满足现场工况要求。     

钢框架外环板式节点力学性能变参数分析

该文分析对象为圆管柱钢框架节点,节点加强方式为外环板加强方式,钢框架节点为中柱节点,节点两端钢梁梁高不同。分析手段采用数值分析法,分析软件为有限元分析软件ABAQUS,变量参数为:轴压比、管壁厚、外环板厚度、梁高差值。通过建立3组共9个有限元分析模型,进行节点的受力模拟试验,并通过试验结果数据整理、总结,得出3个变量参数对钢框架节点力学性能的影响规律。     

双梁桁架龙门起重机主梁的优化设计

针对桁架门式起重机的结构特点，建立结构优化设计模型，以起重机金属结构重量最轻为目标函数，以结构的主要梁构件的截面尺寸为设计变量，以强度、刚度为约束条件，完成了桁架门式起重机主梁的优化设计。     

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。