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。     

退火温度对磁控溅射TiN/TiCN薄膜残余应力、结构及耐蚀性能的影响

采用反应磁控溅射在AZ31合金上制备了 TiN/TiCN薄膜,并对沉积后的薄膜进行真空去应力退火.分别采用X射线荧光光谱仪(XRF)、扫描电镜(SEM)、掠入射X射线衍射(GIXRD)和电化学工作站对退火前后的薄膜进行表面化学成分、形貌结构、残余应力以及耐蚀性能分析.结果表明:薄膜由FCC结构的TiCN和TiN组成.退...     

悬臂梁结构Sm-Fe GMFs的磁致伸缩及幅频特性

采用离子束溅射沉积(IBSD)法在聚酰亚胺衬底上沉积不同厚度Sm-FeGMFs;采用磁致伸缩测量仪测试制备态和不同温度真空退火后薄膜悬臂梁结构自由端偏转量;利用赫姆霍兹系统测量制备态和真空退火后薄膜的幅频特性。结果表明:在低频(0～100Hz)范围内,检测到悬臂梁结构Sm-FeGMFs共振现象,薄膜经过200℃真空退火后,其低场磁敏性明显提高,在74.1Hz的频率下发生共振,其振幅可达到300μm,比制备态时提高了约3倍;制备的Sm-FeGMFs显示出优异的幅频特性,振动与驱动电流的响应曲线表现出很好的跟随性。     

某发电厂高压主汽阀阀杆断裂失效分析

对发生断裂的高压主汽阀阀杆进行了宏观检查、断口分析、金相组织检验和力学性能试验。结果表明:阀杆结构存在缺陷,变截面位置无渗氮层,并且断口位置内外两侧均存在结构突变,此种结构不但造成了应力集中,还缩小了承载面积。阀杆在高温高应力环境下运行,变截面位置无渗氮层保护并且应力集中,导致裂纹在此处产生。主裂纹沿着阀杆最薄弱的45°斜面扩展,最终导致阀杆断裂。     

Ag-Cu-Ti钎焊金刚石的界面结构及热应力分析

采用Ag-Cu-Ti钎料对金刚石进行真空钎焊实验,实现了金刚石与钢基体的高强度连接.采用SEM对金刚石与钎料界面、金刚石表面碳化物形貌进行观察分析,采用EDS分析金刚石表面碳化物的成分,利用XRD对焊后金刚石磨料的进行物相分析,采用Raman光谱对焊后的金刚石是否石墨化、残余应力进行分析.结果表明:Ag-Cu-Ti钎料中的Ti元素在界面处发生偏析,并在金刚石表面生成尺寸小于1μm的块状TiC.金刚石在焊接过程的高温下没有发生石墨化.金刚石中的最大拉应力位于磨粒顶部,为60 MPa,最大压应力在底部,为120 MPa.最后在界面上形成了金刚石/TiC/钎料/钢基体的梯度结合层.     

新型先导式无静差水压溢流阀的动静态仿真分析(英文)

设计了一种新型先导式无静差水压溢流阀,介绍了该阀的结构特点。根据局部假设,建立了溢流阀精确的数学模型。通过实际参数,求出了无静差水压溢流阀的静差。借助 Matlab/Simulink软件对新阀结构进行了动静态仿真分析,并对该阀在 31 MPa 工作情况下的进行了动静态和稳定性分析。仿真分析表明,该阀有很好的动静态特性,响应时间可以达到 12sm,幅频宽达到 86Hz,相频宽达到 87.6 Hz。     

基于流固耦合的阀芯旋转式高速开关阀结构优化

在阀芯高速旋转时,阀芯旋转式高速开关阀内部流场会对阀结构强度产生影响。针对此问题,利用 Fluent对阀进行动态流场分析,将流场仿真结果作为压力载荷,通过 Static Structural 进行流固耦合分析,在此基础上,对阀芯旋转式高速开关阀的结构进行优化。结果表明：阀内部应力整体分布规律为:越靠近中心应力越大,越靠近边缘应力越小,阀芯中心圆柱与阀芯台肩的接触面为阀的危险区域;阀套窗口处油液流动速度变化梯度明显,对阀套产生显著压力冲击;通过对阀套窗口进行倒角处理、阀芯细化等优化,使得阀内部应力强度减弱,流体对阀的压力冲击显著降低。     

单腔体压电叠堆泵的结构设计与实验研究

对单腔体压电叠堆泵进行了结构设计,并制作了实验用样机.分析了阀的工作原理,在阀体选择上选用了一种简单的薄膜阀.设计了正弦信号发生器电路,将产生的正弦信号经过电压放大和功率放大后,作为该泵的电源驱动,并对该泵的工作性能进行较为系统的实验测试和研究.实验测试表明:该泵工作性能稳定,其流量的最佳工作频率约为25Hz,输出压力的最佳工作频率约为7Hz.     

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.     

12000吨锻造水压机动梁产生裂纹的原因

本文分析国产万吨锻造水压机动梁产生裂纹的原因,提出压机横梁的最大应力值并不在中截面处(简支梁的危险截面),而是在结构形状发生突变的过渡部位或工艺孔边;论证了用简支梁计算公式对横梁进行强度设计是不合适的,建议采用有限元计算方法。     

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).     

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.     

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.     

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。