船舶靠泊防撞液压缓冲系统研究

给出船舶靠泊防撞装置及液压缓冲系统,详细阐述其工作原理,对系统元件进行选型,建立船舶撞击防撞装置的系统数学模型,基于Simulink进行系统仿真研究,得到船舶位移速度变化曲线和缓冲油缸工作腔压力流量变化曲线,最后研究溢流阀预压缩量和船舶等效质量对系统缓冲性能的影响。仿真结果表明:溢流阀弹簧预压缩量和船舶等效质量对系统动态性能均有较大影响,弹簧预压缩量增大,船舶位移和缓冲时间均减小,缓冲油缸工作腔压力增大,弹簧预压缩量对工作腔流量没有影响;船舶等效质量增大,船舶位移和缓冲时间均增大,船舶等效质量对缓冲油缸工作腔最大压力和最大流量也没有影响。     

液压油缸圆柱形缓冲装置缓冲过程仿真与参数优化研究

研究了液压油缸缓冲装置的工作机理,建立了液压油缸圆柱形缓冲装置缓冲过程的数学模型和Simulink仿真模型;针对缓冲装置的结构参数对活塞末速度和缓冲腔最大压力的影响,建立了优化目标函数,进行了结构参数寻优。研究成果可用于液压油缸圆柱形缓冲装置的设计和结构优化。     

封闭式多孔形液压缓冲缸仿真与研究

基于液压缸缓冲套的工作原理,提出了一种封闭式多孔形液压缓冲缸。活塞在运行过程中通过不断改变缸套总节流面积,使得速度快速平稳下降,从而起到缓冲作用。并建立了数学仿真模型,用AMESim软件对缓冲缸工作过程进行了仿真,得出了活塞的位移和速度曲线,以及缓冲腔的压力曲线。仿真结果证明了该缓冲缸能很好地满足实际应用要求。     

冲击气缸的数学建模与动态仿真

以冲击气缸为研究对象,运用变质量气体热力学理论建立了该气缸工作过程的数学模型;在该模型基础上,利用四阶定步长龙格-库塔算法求解方程,得到了冲击气缸内冲击活塞速度、位移以及各腔室压力随时间的变化曲线,并对曲线的变化趋势进行了理论分析.通过仿真计算还可以得出冲击气缸的运动特性,以选取最佳行程获得最大冲击功.     

无人机液压弹射装置能源系统仿真研究

基于功率键合图理论建立了无人机液压弹射装置能源系统的动态数学模型,应用Simulink对其工作过程进行了仿真研究,得到了无人机发射过程中液压系统的压力、流量特性以及液压缸活塞的速度、位移随时间的变化规律,同时给出了同一弹射装置在不同工作压力下发射不同质量无人机时的起飞速度.由于液压缸活塞是通过压缩油液缓冲减速,因此笔者通过改变油液体积弹性模量,分析了打开卸荷阀液压缸活塞的震荡情况,为无人机液压弹射装置的研制及改进提供了参考.     

加工番茄自动分选装置弹齿气缸的仿真研究

为研究气缸缸体上开有小孔的新型弹齿气缸的工作特性,建立气缸工作行程的数学模型,运用热力学第一定律和牛顿第二运动定律建立气缸内部腔体动态特性微分方程组,利用M atlab中的四阶龙格-库塔法求解方程,得出气缸工作过程中腔室压力以及活塞位移、速度、驱动力随时间变化的动态曲线,并对曲线变化趋势进行理论分析。结果表明:开孔位置取在气缸行程15 mm处的新型气缸在行程结束时进气腔压力趋近于大气压,且动能较小,对减小活塞冲击、快速复位、减少响应时间有明显作用。     

液气锤冲击振动及对基础影响的研究

阐述了液气锤的组成、工作原理及工作过程,通过对液气锤工作过程中的力学特性分析,建立了设备工作过程中的数学模型;利用MATLAB软件构建SIMULINK模型对锤体系统的振动过程以及对基础产生的激励进行仿真,得到了不同工作腔气体压力、支撑缸气体压力和等效刚度系数下液气锤锤体的振动曲线以及基础振动曲线;分析了工作腔气体压力、支撑缸气体压力和等效刚度系数对锤体系统的振动特性及对基础产生激励的影响,为设备优化设计提供依据。     

基于Automation Studio的双吊点式液压启闭机液压系统仿真分析

以某典型双吊点液压启闭机液压系统为例,介绍双吊点液压启闭机液压系统组成,分析工作原理及系统特性。应用Automation Studio软件搭建启闭机液压系统模型,设置各元件的结构参数和工作参数,并对液压启闭机启门和闭门两个工作过程进行仿真,获得油泵出口压力曲线、油缸工作腔压力曲线以及活塞速度、位移曲线。计算启门和闭门时间,并对同步系统在两油缸位移差为18 mm的条件下进行仿真,获得系统的调整时间。     

新型高压电-气比例阀缓冲气控腔性能分析

针对某控制装置中新型高压电-气比例阀提出了大容积缓冲气控腔的设计结构,以满足该阀高压力、大流量、工作范围宽的工作需求.建立了高压电-气比例阀的数学模型,分析了缓冲气控腔对该阀动态性能的影响,结果表明,增加缓冲气控腔容积,可提高高压电-气比例阀输出气体流量稳定性,减弱控制装置负载加速度的振荡.此外,采用数值模拟计算的方法,对缓冲气控腔流场特性进行了研究.结果表明:该腔压力呈环状分布,腔内存在涡流;缓冲气控腔气体入口位置接近该腔压力输出平面时,其流场特性要优于气体入口远离输出压力平面的情况.     

车用液压缓冲器动态特性研究

为研究履带车辆平衡肘限位液压缓冲器的工作特性,在分析液压缓冲器缓冲机制的基础上,建立了缓冲过程的数学模型.采用四阶龙格-库塔数值计算方法,运用MATLAB编程进行仿真计算,得出缓冲器动态特性曲线.对影响液压缓冲器缓冲特性的因素进行了分析.研究结果表明:合理选择活塞与缸壁的缝隙、节流孔的大小及位置对缓冲器的缓冲性能非常重要;冲击载荷的初速度对缓冲器的最大缓冲力影响很大,而冲击质量对最大缓冲力影响很小.     

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.