LG-730冷轧管机结构力学分析

LG-730冷轧管机是国内最大规格伺服控制型两辊轧机,本文建立了其机架装配应力应变有限元模型,分析了LG-730机架装配在最大载荷下的变形和应力分布,在此基础上,对轧机结构进行了优化:两边机架底座宽度各减小了10 mm,机架筋板厚度由原来的120 mm减小到100 mm,机架两边厚度各减小了20 mm。优化后机架重量降低了,机架的刚度和强度分布更加均匀合理。研究结果对LG-730机架结构设计具有指导意义。     

基于有限元的轧机机架的机械性能分析

在对板簧轧机机架的结构形式进行深入分析的基础上,建立了轧机机架的三维模型.以ANSYS11.1有限元软件作为分析工具,对两种不同形式的轧机机架进行三维模型的有限元模拟,计算了机架的应力和位移,得到了机架的应力图与位移图,得出机架各单元和各节点的位移量及应力值.分析结果表明,有中间横梁机架的Y向位移明显小于无中间横梁的机架结构,且设备刚度提高了18.77%,为轧机机架的设计、改造、以及提高轧制精度提了供理论依据和参考数据.     

连轧管机架三维仿真设计及有限元分析

本文就φ１８０ｍｍ连轧管机机架的三维仿真设计和该机架的有限元分析作一浅析。应用ＵＧ／Ａｓｓｅｍｂｌｉｅｓ模块对机困进行三维仿真设计,并应用有限单元法,对连轧管机架进行了静力有限元分析。对同一载荷不同边界条件下六种力学模型进行了分析比较。探讨了该机架结构的应力分布规律,结构刚度和强度特性,为优化产品结构提供了理论依据,本文仅提供六种力学模型中其中最佳一种计算过程和三维仿真设计。     

中厚板轧机组合式机架的力学行为

根据某钢铁公司2600mm中厚板轧机组合式机架的参数,利用Pro/E对机架进行三维建模,将其导入ANSYS中进行有限元分析。利用预紧力单元法,通过控制机架拉杆预紧力,得出影响机架最大等效应力和变形的规律,从而获得理想的拉杆预紧力。分析了在理想预紧力情况下,机架各组件的应力与变形情况,确定了机架受力危险点的位置,并对机架进行了强度与刚度校核,为组合式机架的设计和改进提供理论依据。     

JCL-3×1800液压剪板机机架的有限元分析及结构改进

采用有限元软件ANSYS对JCL-3×1800液压剪板机机架施加移动载荷,分析机架在各个载荷步下的变形、等效应力、等效应变,结果表明机架危险截面的最大等效应力在30~50 MPa之间,而机架屈服极限为235 MPa,因此机架结构满足强度要求。以有限元分析的结果为基础,提出4种结构改进方案,并分别进行分析,得到较优的方案,为机架的结构改进提供依据。     

快锻液压机机架静动态数值模拟

采用三维十节点实体单元对12.5 MN双柱下拉式快锻液压机进行了静动态有限元计算,得到了液压机机身在给定工况下的静动态应力位移分布规律.快速锻造液压机已成为重要锻造设备之一.本文建立了12.5 MN双柱下拉式快锻液压机机架三维有限元模型,对其应力及位移分布进行了静动态分析.研究表明:机架四角为危险截面;静态和动态下,应力和位移的分布趋势基本一致;机架在动态载荷冲击下,危险截面的最大应力将会增加40%左右;偏移载荷将会使机架危险截面的最大应力增加20%左右.     

新型6300kN模锻液压机结构有限元分析及优化

利用ANSYS软件中的APDL语言对6300kN液压机组合机架进行三维几何建模,并根据机架的力学模型建立有限元模型,进行组合机架的有限元分析及侧梁结构化设计。对组合机架进行静态有限元分析,得到机架的应力和位移分布规律,对机架的刚度和强度进行了校核。通过对组合机架进行模态分析,得到机架的前10阶的固有频率与相应振型,确保机架的动态特征符合设计要求。根据有限元分析结果,编制相关程序对侧梁结构进行优化,获得理想的结构参数,达到轻量化的目标。     

12.5 MN双柱快锻液压机机架的有限元分析

快速锻造液压机已成为目前重要的锻造设备之一.本文建立了12.5 MN双柱快锻液压机的整体三维有限元模型.针对其预紧组合机架的结构形式,对机架整体刚度的主要影响因素进行分析.根据偏载工况得到了预紧系数、拉杆与立柱强度等因素之间的关系,为机架整体设计提供了理论依据.对压机进行静态有限元分析,得到了机架主要部件的应力和位移的分布规律,并提出改进方案,确保机架的刚度和强度以及整体性指标达到使用要求.     

皮尔格钢管轧机机架的有限元分析

本文采用Ｉ－ＤＥＡＳ软件对皮尔格轧机机架进行了有限元强度分析，精确计算出机架应力、变形分布及应力集中，为机架的改进设计提供了准确可靠的强度依据。     

基于有限元法的四辊卷板机机架优化设计

机架作为四辊卷板机的主要承力部件,其强度、刚度及动力学特性不仅影响主机的使用寿命,同时很大程度上制约了产品的卷制精度。因此,以四辊卷板机的高机架为研究对象,应用有限元分析方法校核其刚度、强度,为机架的设计优化提供理论依据。同时对其关键部位处筋板应用实验点设计法,求得最优筋板尺寸,使机架的位移大幅降低,应力分布更为合理。最后,对机架进行模态分析,为之后机架动力学特性的研究提供参考依据。该研究提供了机架关键位置的优化设计方案,使机架等效应力分布更为均匀,并大大提升了机架的刚度,为卷板机高精度运行提供了保障。     

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。