RV减速器传动误差特性分析与实验研究

以高精度RV-80E减速器为研究对象,针对其结构特点,利用ADAMS多体动力学仿真软件建立RV减速器刚柔耦合模型,并验证模型的正确性。采用刚柔耦合模型设计了多组不同误差的仿真样机,并通过仿真分析了不同误差因素对整机传动精度的影响。分析不同的误差组合方式,得出正等距和负移距、负等距和正移距的误差组合可以有效地减小传动误差对整机传动精度的影响。通过实验测试,分析了国内外RV减速器传动精度的差异。分析了RV-80E减速器传动误差和误差频谱,确定了二级传输误差为影响传动精度的主要原因。研究结果为减速器批量化生产提供了参考。     

RV减速器传动精度特性分析与实验研究

以高精度RV 80E减速器为研究对象,针对其结构特点,利用ADAMS多体动力学仿真软件建立RV减速器的刚柔耦合模型,并验证了模型的正确性。同时利用刚柔耦合模型设计了几组不同误差的仿真样机,通过仿真分析了不同误差因素对整机传动精度的影响。通过不同的组合误差因素,得出正等距+负偏移距或负等距+正偏移距的误差组合可以有效地减小传动误差对整机传动精度的影响,最后通过实验研究,得出了影响第二级传动误差过大的主要因素,为RV减速器的生产制造提供了一定的理论依据。     

基于线性自抗扰控制的激光通信跟瞄机构机电联合仿真

为分析空间激光通信组网从光端机跟瞄机构的性能、提高跟踪精度,对跟瞄机构的控制与仿真技术展开研究。建立跟瞄机构机械系统模型,设计基于线性自抗扰控制的控制系统;使用ADAMS和Simulink搭建机电联合虚拟样机,完成跟瞄机构跟踪性能的仿真分析。结果表明：基于LADRC的联合仿真控制系统消除了摩擦扰动造成的速度跟踪死区,跟踪精度优于传统PID控制;对频率为0.1 Hz的正弦信号跟踪误差最大值为105μrad,符合跟瞄机构的指标要求,可以作为实物样机研发的参考依据。     

基于ADAMS的多级液压缸系统仿真建模

以多刚体系统动力学理论为基础，以驱动旋转负载为例，讨论了多级液压缸系统的动态模型的建立问题。在ADAMS下，采用定义设计变量、状态变量和状态方程的方法，建立了多级液压缸系统的仿真模型，并与负载模型相耦合，给出了仿真结果。     

RV减速器传动误差分析及ADAMS仿真

以RV减速器为研究对象,分析了零部件的加工、装配误差对RV减速器传动的作用形式,将LIN的平移扭转耦合模型和质量弹簧误差等价原理相结合,建立该系统动力学传动误差的数学模型并进行求解;并以数学模型参数为基础,基于ADAMS动力学仿真软件建立了含有各类误差的三维模型并进行了仿真分析,通过对仿真的RV减速器输入输出速度数据的测试分析得到传动误差为2″～40″,与数学模型计算结果相似;通过对RV减速器数学模型计算的传动误差和ADAMS仿真的传动误差频谱图分析,得出影响传动误差大小的主要因素是二级摆线针轮传动。仿真结果验证了数学模型的准确性。     

数字液压缸联合仿真与试验研究

以航天器转运平台使用的数字液压缸为研究对象,根据其结构特点和内部闭环控制原理,利用三维建模软件和ADAMS软件建立其多体动力学模型,利用AMESim软件建立其液压模型,并通过软件接口将液压模型集成到ADAMS环境中,从而实现了联合仿真。利用仿真模型,重点研究了数字液压缸的定位精度,并通过试验验证了模型的准确性。根据仿真及试验提出了通过调整输入脉冲量提高精度的方法,可以满足转运平台工作时的精度要求。同时还通过仿真发现,供油压力波动会导致活塞杆运行时的抖动,增大定位误差。     

运动学误差模型变体下的机械臂标定精度研究

为进一步提高机械臂运动学标定精度,研究不同D-H建模方式下运动学误差辨识精度的差异,为运动学误差准确建模提供理论依据。围绕SD-H和MD-H运动学误差模型的各种变体形式,量化对比各模型变体的性态水平和线性化误差,并分析二者对运动学标定精度的综合影响。研究结果表明：x-z-y欧拉变换会破坏MD-H运动学误差模型最小性,不适用于运动学标定;其余满秩MD-H模型性态水平优于SD-H模型两个数量级;MD-H建模时引入的线性化误差与SD-H数量级等同;在模型性态水平和线性化误差综合作用下,较强测量噪声环境中的SD-H模型运动学标定精度(0.1%~39.3%)优于MD-H模型(0.1%~71.2%);角度类与位置类的运动学参数误差的辨识精度差异显著。研究成果为机械臂标定的精确建模以及误差类型与辨识方法的合理匹配提供了理论依据。     

挖掘机自动挖掘轨迹规划与动态优化控制

以挖掘机为研究对象,建立挖掘机工作装置运动学和动力学数学模型,通过五次多项式插值方法将运动轨迹离散,采用MATLAB编写离散运动轨迹程序并将其计算结果与ADAMS仿真结果进行对比,最终确定动力学模型参数;其次,建立基于动力学模型的Simulink和ADAMS联合仿真模型,在动态控制中采用PD控制方法,进行轨迹规划联合仿真并试验。结果表明：基于动力学模型的运动轨迹控制方法可以有效避免始末位置和液压缸输出力变化的突变,采用动态控制中的PD控制方法,得到的收敛趋势相较于未优化的要收敛近50%;液压缸输出力变化稳定,其误差在5%附近,提升了自动挖掘运动轨迹控制精度。     

无人机水下发射试验系统弹射性能的仿真研究

为研究无人机水下发射的可行性及其弹射过程动力学性能，对系统主要参数进行影响规律和灵敏度分析。通过研究机械结构和传动系统的耦合特性，建立基于AMESim和ADAMS的水下发射试验系统动力学联合仿真模型，在发射角10°～90°范围内对3种类型无人机进行仿真，得到发射速度随发射角和储气瓶压力的变化规律；利用局部灵敏度分析方法，对储气瓶压力、储气瓶容积、气缸有效面积和行程4个关键参数进行了影响发射速度和加速时间的规律分析。结果表明：在相同压力下，随着发射角的增大和无人机模型质量的减小，其脱离发射架的速度逐渐增大；影响发射速度灵敏度最大的参数为储气瓶压力，随着压力的增大，速度增大的幅度逐渐减小；影响加速过程时间灵敏度最大的参数为储气瓶压力和气缸有效面积。     

水泥混凝土整平机自动升降液压系统仿真研究

水泥混凝土整平机自动升降液压控制技术对于降低人工作业误差、提高平整作业的精度和质量非常关键.为了便于开展进一步的相关研究,进行自动升降液压控制系统仿真.首先运用ADAMS软件建立整平机整平板和激光接收器系统模型并进行仿真,论证了动力学模型可以很好地实现激光接收器与整平板的自动升降功能;然后运用AMESim软件进行整平板...     

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。