基于ANSYS的高速冲床连杆疲劳可靠性分析

根据疲劳失效准则建立了高速冲床连杆疲劳可靠性分析的极限状态函数;考虑连杆的材料强度、疲劳系数及载荷等参数的随机性,利用ANSYS的概率设计功能,采用蒙特卡洛法对其进行疲劳可靠度计算、灵敏度求解,验证了连杆的疲劳可靠性,得出了影响连杆疲劳可靠性的主要因素,并据此对现有设计提出了改进建议。结果表明:采用ANSYS的概率设计功能对高速冲床连杆进行疲劳可靠性分析是可行的,为连杆的结构可靠性设计提供了新思路。     

基于随机SLD法的车削颤振可靠性研究

针对车削加工颤振预测问题,研究了车削加工系统结构动态特性参数具有随机特性的情况下颤振可靠性建模及求解问题。建立了单自由度车削加工系统动力学理论模型,提出了车削加工颤振系统的随机SLD可靠性模型,采用蒙特卡洛方法进行了可靠度求解。对一台CJ0625车床进行频响函数测试,给出了具有随机参数的车削加工系统频率响应函数和颤振稳定性叶瓣图(SLD)。对设定的16组转速、切宽加工参数进行颤振可靠度计算,其结果与确定性SLD方法分析结果进行比较。     

基于自由漂浮空间机器人的空间焊缝跟踪

空间机器人可以在宇宙空间自由飞行或浮游,协助或代替宇航员完成空间焊接作业.以平面自由漂浮双臂空间机器人为对象,研究了焊枪跟踪空间焊缝的位置与姿态的路径规划问题.在双臂空间机器人运动学模型基础上,对焊枪末端点速度的计算方法进行了深入讨论和分析,进而将空间机器人双臂末端点速度的求解问题定义为一个高维空间搜索问题,并采用遗传算法对其进行了优化计算,最后提出了双臂空间机器人跟踪空间焊缝的运动规划算法,并通过直线与圆弧焊缝跟踪的仿真试验进行了验证和分析.     

基于扩展任务的双臂机器人位姿优化

为了能够在不修改工业机器人控制器的逆解算法的前提下对双机械臂系统进行位姿优化,同时要求以双臂各向同性指标为强化目标,设计出基于扩展任务的双臂姿态优化方法。首先对双臂机器人的协作任务进行了运动学分析与建模,然后基于最近被提出的一种新型的通用冗余机械臂位姿优化方法对双臂位姿优化进行数学描述,并表明了优化指标-双臂各向同性指标的几何和物理意义。再利用蒙特卡洛采样方法和非线性回归拟合出了主机械臂在操作空间的位姿与协作任务的位姿之间的数学关系,即扩展任务的数学模型。最后在ABB Robot Studio机器人仿真软件中对双臂系统进行主从协作运动任务的仿真,结果表明:利用扩展任务的优化方法可以实现以各向同性指标强化为目标的双臂系统的位姿优化,可以使两只机械臂都远离肘关节奇点和肩关节奇点,并且表明本质上还可以减小机械臂的条件数的值。     

采用粒子群算法耦合遗传算法优化双臂机器人模糊逻辑控制研究

为了提高双臂机器人运动轨迹追踪精度,降低运动过程中的抖动幅度,引入混合粒子群算法优化双臂机器人模糊逻辑控制,并对误差和力矩进行仿真。创建双臂机器人平面运动模型简图,建立机械臂运动方程式。分析了模糊逻辑控制规则,引用模糊逻辑控制不同成本函数定义机械臂运动轨迹的平方误差均值、误差的绝对值及控制力参考误差,采用遗传算法耦合粒子群算法优化模糊逻辑控制的成本函数。通过MATLAB对优化模糊逻辑控制的双臂机器人运动轨迹控制力矩进行仿真,并且与模糊逻辑控制仿真结果形成对比。仿真结果显示:受外界环境干扰时,双臂机器人模糊逻辑控制采用遗传算法耦合粒子群算法优化后,不仅运动轨迹追踪误差较小,而且输入力矩值也较小。双臂机器人模糊逻辑控制采用遗传算法耦合粒子群算法优化后,能够提高机器人运动轨迹追踪精度和降低控制系统抖动幅度。     

移动机器人机械臂运动分析及轨迹规划

以自行研制的移动双臂机器人为对象,采用D-H参数建模法建立双臂机器人数学模型,利用MATLAB的Robotics toolbox工具箱建立机器人手臂关节的运动学模型,分析机器人的运动学问题和基于关节空间的轨迹规划问题。通过SolidWorks建立双臂机器人的三维模型并导入Adams仿真软件,对虚拟样机模型进行动力学仿真分析。通过仿真验证了双臂机器人的设计可以满足工作性能的要求,为评价其力学指标和后续的驱动系统的硬件选型提供了重要的理论依据。     

基于CAN总线结构的服务机器人模块化双臂系统构建

针对商品化工业机器人手臂系统封闭、开放性差的问题,采用机器人可重构模块来构建机器人的双臂系统.在分析机器人手臂构成特点的基础上,进行了手臂模块的选型,完成了由模块化关节组成的服务机器人双臂硬件平台的搭建;通过分析手臂功能模块化的特点,设计了手臂的分布式控制系统方案,并通过实验验证了双臂软硬件系统构建的正确性及稳定性.     

基于粒子群算法的拆装机器人逆解研究

为了使连续生产线工件拆装实现自动化,设计了一种满足工业需求的关节型拆装机器人,并对其样机加工装配。采用D-H法将机器人的三维模型转化为连杆坐标系,通过坐标变换求出机器人的运动学正解。由于机器人结构中连杆关联的原因,采用常规的逆变换法和几何法不能求出逆解,因此提出以"目标点位姿误差最小"为目标函数,各关节转角极限为约束条件,利用粒子群优化算法,对机器人的逆解求最优解。最后,通过对机器人位姿点和连续运动轨迹进行逆解求解验证并对其运动过程仿真分析。实验结果表明该方法求逆解速度快、精度高,能够满足规划的路径,克服了传统方法仅适应于特殊构型机器人的逆解的不足,解决了该机器人的逆解求解。     

双臂机器人协调搬运运动的运动学分析

针对双臂机器人协调搬运运动模式,文章提出了一种新的坐标系变换方法。以双SCARA机器人组成的双臂机器人为研究对象,首先运用DH算法推导出单臂SCARA机器人的运动学方程。然后建立双臂机器人协调搬运坐标系,找出搬运工件与双臂机器人的约束关系,根据规划的搬运工件轨迹求出主机械臂末端的运动轨迹,根据主机械臂各个关节的实际关节角度求解出从臂的运动轨迹。最后采用Adams与MATLAB联合仿真实验平台进行仿真验证,实验结果表明双臂机器人可以完成定姿态与变姿态两种运动模式。     

水下机器人柴电动力系统可靠性研究

大型化是未来水下机器人发展的重要趋势,大排水量水下机器人多采用柴油机作为动力系统的动力源。本研究面向水下机器人柴电动力系统在设计过程中选用单套或双套柴油机组技术方案的问题,进行系统可靠性分析,对比单套柴油机组与双套柴油机组在不同工况下的系统可靠度。结果表明:巡航状态下双套柴油机组可靠度较单套柴油机组提高25%以上;高速航行状态下双套柴油机组可靠度较单套柴油机组降低最大可达31.2%;巡航状态与高速航行状态各占全部工作流程一半时,双套机组的系统可靠度与单套机组的系统可靠度相同。     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.