基于ANSYS Workbench的八连杆压力机刚柔耦合模型动力学分析

为考虑压力机柔性体部件对机械运动的影响,以八连杆压力机的传动机构为研究对象,使用Pro/E软件对八连杆传动机构进行参数化实体建模,分别应用ANSYS Workbench软件中的Rigid Dynamic模块及Transient Structural模块,在对八连杆压力机的传动机构做刚体运动学仿真的基础上,进行该传动机构的刚柔耦合动力学分析,得到压力机传动机构的运动特性曲线和等效应力曲线及分布图。结果显示,主拉杆最大等效应力高于材料许用应力,将下轴孔尺寸优化为69 mm后,最大等效应力大大降低,符合主拉杆强度要求。这种方法实现了在同一软件平台中进行刚体运动学和刚柔耦合动力学仿真分析,通过两者比较可得出,刚柔耦合模型更能反映出机构的真实运动情况。     

新型激振台的动力学分析与参数优化

提出了一种新型的激振台并研究其动力学特性,基于Sold Works和ADAMS软件建立激振台的虚拟样机模型。利用ADAMS的柔性体模块建立弹簧的柔性体模型,对激振台进行刚柔耦合动力学分析,并进一步分析了固有频率、振型及频率响应。根据分析结果优化弹簧和柔索的刚度,优化后的仿真结果表明:激振台的稳定性和振动情况都得到了提高。     

考虑柔性的货车动力学研究及建模优化

应用柔性多体系统动力学进行货车动力学仿真研究,以货车C70为研究对象,把车体、侧架和摇枕作为柔性体,其余作为刚体,组成刚柔耦合动力学模型进行动力学仿真计算,分别在空、重车情况下与多刚体模型车辆振动响应、动力学性能结果对比,寻找几种模型不同工况下差异,提出最优建模方式。仿真结果表明:研究车辆系统振动响应时可以忽略侧架和摇枕柔性,而车体柔性影响明显;对于车辆运行稳定性和平稳性车体、侧架和摇枕柔性有一定影响但是影响不大,对于曲线通过性能有必要同时考虑车体和侧架柔性影响。     

基于虚拟样机技术的并联机床多柔体系统运动学仿真分析

通过对3-TPT并联机床的运动特性进行分析,得出了其运动学方程,由于并联结构的特点,其考虑杆件柔性的多体系统的运动特性难以用方程求解。因此,本文利用有限元分析软件ANSYS,建立了机床柔性杆件的有限元模型,然后利用多体动力学仿真软件ADAMS形成了机床的多体系统模型,对其进行了运动学仿真,得出了运动学仿真曲线,并分别将刚体和柔性体仿真结果进行对比。结果表明柔性多系统的运动较多刚体系统的运动更为平稳,其运动能更真实、准确地反映出并联机器人的实际运动特性。     

多电机驱动的双辊夹持旋压成形装置的动力学仿真

对双辊夹持旋压成形装置进给驱动系统进行了动力学分析,得到了装置进给驱动系统的动力学模型。利用多体动力学软件ADAMS和有限元软件ANSYS对多电机驱动的双辊夹持旋压成形装置进行了多刚体模型和刚柔耦合模型的动力学仿真,通过比较装置夹具和旋辊头运动轨迹的理论结果和仿真结果验证了所建立模型的正确性。仿真过程充分考虑了滑块与导轨之间的等效阻尼、刚度和摩擦等非线性因素以提高仿真精度。刚柔耦合模型仿真结果显示,旋辊头进给速度波动的幅度为±0. 065%,周期为0. 42 s,夹具进给速度波动的幅度为±0. 4%,周期为0. 71 s,表明丝杠的弹性变形会影响装置进给驱动系统的运动精度。     

基于ADAMS的塔式起重机动力学仿真

主要介绍了ADAMS柔性体基本理论及在ADAMS中调用柔性体的几种方法。着重研究了如何在ADAMS中引入ANSYS模态中性文件,构建机械系统仿真的刚柔耦合动力学模型。以建筑机械产品塔式起重机为例,具体说明ADAMS软件在该实体模型的柔性体运动仿真分析中的实效,并得出了力、力矩等随时间变化的规律。     

基于刚柔耦合建模的6R机器人位置误差分析

由于机器人在工作过程中受运行速度和加速度以及末端负载等因素变化的影响,其连杆和关节产生的形变会引起末端执行器的位置误差,针对这一问题,以FANUC M-6i B机器人为研究对象,采用仿真与试验相结合的方法,对机器人末端位置精度进行研究。运用DH法则建立运动学模型和位置误差模型,分析机器人DH参数发生微小变化对末端位置误差的影响;在ADAMS环境中进行刚柔耦合动力学仿真,在同时考虑关节柔性和连杆柔性的前提下分析运行速度和加速度、末端载荷变化对机器人末端定位精度的影响;通过自主设计的测量装置及变载荷方盒进行试验,试验与仿真结果的对比表明利用刚柔耦合动力学模型模拟计算机器人末端误差具有较好的一致性。     

基于ADAMS和ANSYS的高速冲床执行机构动态仿真分析

在虚拟样机仿真分析可行性得到论证的基础上,介绍了一种基于虚拟样机技术的高速冲床执行机构有限元分析方法;采用SolidWorks、ANSYS和ADAMS联合仿真的关键技术,建立高速冲床执行机构的多刚体及刚柔耦合的虚拟样机模型,对其进行仿真分析,比较了两者的仿真结果,得出刚柔耦合模型更能反映机构的真实运动;根据仿真得到的执...     

某激光切割机悬臂梁的动力学仿真研究

应用LMS.Virtual.lab motion多体动力学仿真工具,以多体动力学理论为基础,建立了包含柔性悬臂梁和柔性丝杠的激光切割机刚柔耦合模型.通过动力学仿真,分析某激光切割机在运动过程中悬臂梁变形与振动情况,为激光切割机悬臂梁的设计提供理论依据.     

基于ADAMS和ANSYS的机械臂刚柔耦合运动学分析

针对机械臂的设计要求,设计了一种由两个铰链四杆机构组成的双自由度机械臂,利用ADAMS建立机械臂的刚性体模型,仿真得到不同时刻的运动参数曲线;利用ANSYS建立指定部件的柔性体模型,得到不同阶数的模态频率和模态振型值;利用ADAMS和ANSYS进行联合仿真后,得到机械臂的刚柔耦合模型,仿真结果表明:柔性体模型在z方向发生了微小位移变化,x、y方向位移波动范围增加了10 mm。利用Altium Designer软件绘制控制电路图并进行了实物制作,实验结果表明该机械臂具有广泛的适用性。     

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。