Mechanical characteristic and failure mechanism of joint with composite sucker rod

Composite sucker rods are widely used in oil fields because of light weight,high strength,and corrosion resistance.Bonded technology becomes the primary connection method of composites.However,the joints with composite sucker rods are prone to debone and fracture.The connected characteristics are less considered,so the failure mechanism of the joint is still unclear.Based on the cohesive zone model(CZM)and the Johnson-Cook constitutive model,a novel full-scale numerical model of the joint with composite sucker rod was established,and verified by pull-out experiments.The mechanical properties and slip characteristics of the joint were studied,and the damaged procession of the joint was explored.The results showed that:a)the numerical model was in good agreement with the experimental results,and the error is within 5%;b)the von Mises stress,shear stress,and interface stress distributed symmetrically along the circumferential path increased gradually from the fixed end to the loading end;c)the first-bonded interface near the loading end was damaged at first,followed by debonding of the second-bonded interface,leading to the complete shear fracture of the epoxy,and resulted in the debonding of the joint with composite sucker rod,which can provide a theoretical basis for the structural design and optimization of the joint.

Effect of rod-like grain on properties and toughening mechanism of 3Y-TZP/Al_2O_3 ceramics

In-situ rod-like Al2O3 grain was prepared by adding CAS multiphase additives under the sintering condition of 30 MPa, 1 550℃and 1 h.The sintering behaviors,microstructure,toughening mechanism and access of Al2O3 ceramics were investigated by SEM,EDS and WDW omnipotent electronic mechanical testing machine,etc,and the crack propagating model of cylindrical crystal/3Y-TZP composite toughening Al2O3 ceramics was established.The results show that the composite additives prompt the anisotropic growth of Al2O3 grain,which strengthens toughening effect of 3Y-TZP in 3Y-TZP/Al2O3 composite ceramics.Moreover, the experimental material density is near to theoretical density,bending strength is 556.35 MPa,and fracture toughness is 6.73 MPa·m1 /2.The mechanical properties of the materials are obviously improved.

Effect of Cerium on Mechanical Performance and Electrical Conductivity of Aluminum Rod for Electrical Purpose

The effect of rare earth element Ce on mechanical performance and electrical conductivity of aluminum rod for electrical purpose were studied under industrial production condition. Using optical microscope, SEM, TEM, EDS and X-ray diffractometer, the microstructure and phase composition of aluminum rod were measured and analyzed. The results indicate that the content of rare earth element Ce is between 0.05% -0.16% in the aluminum rod for electrical purpose. Its tensile strength is enhanced to some extent. The research also discovers that the tensile strength is enhanced remarkably with impurity element Si content increases. Because influence of Si is big to the conductivity, the Si content should be controlled continuously strictly in the aluminum for electrical purpose. Adding rare earth element Ce reduces the solid solubility of Si in the aluminum matrix, and the negative effect of Si on the aluminum conductor reduces effectively. So the limit of in Si content in aluminum rod for electrical purpose can be relaxed moderately.

Modeling and analysis of nonlinear mechanics of a super-thin elastic rod

Nonlinear mechanics for a super-thin elastic rod with the biological background of DNA super-coiling macromolecules is an interdisciplinary research area of classical mechanics and molecular biology. It is also a subject of dynamics and elasticity because elastic bodies are analyzed via the theory of dynamics. It is in frontiers of general mechanics （dynamics and control）. This dissertation is devoted to model a constrained super-thin elastic rod and analyze its stability in equilibrium. The existing research results are summarized. Analytical mechanics is systematically applied to model the elastic rod. The Schroedinger equation for complex curvatures or complex bending moments is, respectively, extended from the case of circular crosssections to that of non-circular ones. The equilibrium of a rod constrained on a surface is investigated.

A general solution for one dimensional chemo-mechanical coupled hydrogel rod

Smart hydrogels are environmentally sensitive hydrogels, which can produce a sensitive response to external stimuli, and often exhibit the characteristics of multi filed coupling. In this paper, a hydrogel rod under chemomechanical coupling was analytically studied based on a poroelastical model. The already known constitutive and governing equations were simplified into the one dimensional case, then two different boundary conditions were considered. The expressions of concentration, displacement,chemical potential and stress related to time were obtained in a series form. Examples illustrate the interaction mechanism of chemical and mechanical effect. It was found that there was a balance state in the diffusion of concentration and the diffusion process could lead to the expansion or the stress change of the hydrogel rod.

A New Type of Continuously Variable Displacement Mechanism Used for Hydraulic Motors

A continuously variable displacement mechanism, which is composed of a hydraulic control valve with mechanical-positional feedback to camshaft, was designed for changing the displacement of traditional camshaft connecting-rod low speed high torque (LSHT) hydraulic motor continuously. The new type of continuously variable displacement mechanism is simple and easy to be made. The structure and principle of a continuously variable displacement mechanism was introduced. The mathematic model of the continuously variable displacement mechanism was set up and its static and dynamic characteristics were analyzed with the help of computer simulation. It can be seen that the cam ring on camshaft of the traditional LSHT hydraulic motor can stop at any position between minimum and maximum eccentricity, according to an input fluid pressure signal. And it can also stay anywhere stably through self-adjusting. Besides, it can work stabilized when load impact or oil leakage exists.

Bi/Bi_(3)Se_(4) nanoparticles embedded in hollow porous carbon nanorod:High rate capability material for potassium-ion batteries

Considering their superior theoretical capacity and low voltage plateau,bismuth(Bi)-based materials are being widely explored for application in potassium-ion batteries(PIBs).Unfortunately,pure Bi and Bibased compounds suffer from severe electrochemical polarization,agglomeration,and dramatic volume fluctuations.To develop an advanced bismuth-based anode material with high reactivity and durability,in this work,the pyrolysis of Bi-based metal-organic frameworks and in-situ selenization techniques have been successfully used to produce a Bi-based composite with high capacity and unique structure,in which Bi/Bi_(3)Se_(4)nanoparticles are encapsulated in carbon nanorods(Bi/Bi_(3)Se_(4)@CNR).Applied as the anode material of PIBs,the Bi/Bi_(3)Se_(4)@CNR displays fast potassium storage capability with 307.5 m A h g^(-1)at 20 A g^(-1)and durable cycle performance of 2000 cycles at 5 A g^(-1).Notably,the Bi/Bi_(3)Se_(4)@CNR also showed long cycle stability over 1600 cycles when working in a full cell system with potassium vanadate as the cathode material,which further demonstrates its promising potential in the field of PIBs.Additionally,the dual potassium storage mechanism of the Bi/Bi_(3)Se_(4)@CNR based on conversion and alloying reaction has also been revealed by in-situ X-ray diffraction.

Study of the axial density/impedance gradient composite long rod hypervelocity penetration into a four-layer Q345 target

Based on the dynamic shock response of the material and structure,the hypervelocity impact processes and mechanisms of long composite rods with axial density/impedance gradients penetration into fourlayer targets were studied through experiments and numerical simulation methods.The propagation law of the shock waves,together with the structural responses of the projectiles and targets,the formation and evolution of the fragment groups formed during the processes and their distributions were described.The damage of each target plate was quantitatively analysed by comparing the results of the experiment and numerical simulation.The results showed that the axial density/impedance gradient projectiles could decrease the impact pressure to a certain extent,and the degree of damage to the target plate decreased layer by layer when the head density/impedance of the projectile was high.When the head density/impedance of the projectile was low,the degree of target damage first increased layer by layer until the projectile was completely eroded and then it decreased.The results can provide a reference for the design and application of long rods with axial composite structure for velocities ranging from 6 to 10 Ma or greater.

铸态下Sn-Bi二元共晶焊料合金的组织特征及其力学性能

研究了四种不同Bi含量(45%、50%、55%、60%)的Sn-Bi二元共晶合金自由凝固下的组织特征和力学性能,探讨了Sn-Bi二元共晶合金的晶体生长机制以及Bi元素含量对合金显微组织的影响。结果表明:Sn-Bi二元亚共晶合金铸态下的金相组织为初生Sn固溶体相和Sn/Bi共晶层片集群构成,随着Bi含量的增加,呈树枝晶形态生长的初生Sn相数量减少,形态长大。初生Sn固溶体相内部脱溶析出大量的杆状或点状Bi相,形成杆状共晶结构;Sn-Bi二元过共晶合金铸态下的金相组织为初生Bi相和Sn/Bi共晶层片集群构成,初生Bi相中基本不固溶Sn元素,呈小平面方式生长,并在在初生Bi相周围包裹生长一层Sn晕圈相。在室温下,Sn-Bi二元共晶合金的硬度和强度随着Bi含量的增加而上升,延伸率随着Bi含量的增加先上升后下降。

岩爆机制及其控制

随着岩体工程向深部发展,开挖引发的围岩大变形和强冲击诱发的动力破坏日益严峻。岩爆作为深部地下工程中常见的一种强动力灾害,被称为岩土工程界的“癌症”,其具有突发性特点,难以有效预报及防治,严重地威胁着施工人员的安全和设备的正常运行。通过对比岩石在真三轴卸荷和单轴压缩这2种应力路径下的储能差异,对岩爆多余能量机制进行探讨。首先,根据岩爆诱发机制的不同,将岩爆分为由应力集中导致的应变型岩爆和扰动诱发的冲击岩爆。然后,模拟开挖诱发的不同类型岩爆的应力路径进而在室内再现各种岩爆现象,并对其机制进行研究,自主研发3套真三轴岩爆模拟试验系统:第1代应变岩爆试验系统、第2代应变岩爆试验系统、冲击岩爆试验系统。同时,在实验室内成功模拟不同类型的岩爆:巷道应变岩爆、巷道交叉点应变岩爆、3个临空面矿柱应变岩爆、矿柱应变岩爆以及动荷载诱发的冲击岩爆。最后,为有效控制岩爆灾害,提出开挖补偿法,并研发具有负泊松比效应的宏观和微观NPR锚杆/索。工程实践证明,NPR锚杆/索能提供高预应力来补偿开挖造成的应力损失,同时具备良好的延展性和吸能效果,可为岩爆灾害的防治提供有效途径。

一种杆长可调的多功能铰链四杆机构模型的设计

设计出一款多功能铰链四杆机构,可使不同机构类型在同一模型上实现。阐述了设计原理,完成了杆长调节机构、限位装置、杆长锁紧装置、机架、多功能连接装置、铅笔固定滑块机构的设计,通过数字化模型呈现其功能。

基于机理仿真的抽油机有杆泵举升系统生产参数优化设计

基于传统经验法和预测模型法的抽油机有杆泵举升系统设计方法在实际应用中要么过于简单要么过于复杂,设计方案的可靠性还有待提升。因此,应用大数据驱动技术从海量抽油机井举升系统设计方案中探索规律,推荐以提高产量和节能降耗为目标的抽汲参数优化设计最优方案,将提升抽油机井举升系统设计方法的科学性和可操作性。文章分析了抽油机井产量主控因素,将软件仿真和现场获取的抽油机井举升系统设计样本进行聚类分析融合得到新的样本库,建立了抽油机井举升系统设计方案的深度学习模型,研究了基于匹配算法的方案相似度模型,开发了抽油机井有杆泵举升系统生产参数设计推荐系统。根据实例计算验证,该系统能够根据待设计井的地质特征和开发特征,从海量样本中匹配到与地质油藏条件相似度高且运行效果良好的举升设计方案,推荐方案的举升参数及举升效果与原有方案相比有较大的提升,证明了计算模型的实际可行性,为抽油机举升系统优化设计提供了新思路及方法。

示范快堆非能动棒驱动机构可靠性指标验证研究

示范快堆非能动棒驱动机构是非能动停堆机构的组成部分之一,用于在反应堆启动时提升非能动棒。非能动棒驱动机构的可靠性验证采用定数试验的方法。由于相关标准在适应性方面存在部分问题,基于相关概率统计理论,推导得出非能动棒驱动机构可靠性验证的统计试验方案,并且制定适宜的试验剖面。试验统计结果满足验证方案的接收准则,设备可靠性水平高于指标要求的置信度为70.3%。

基于数字孪生的航天发射塔摆杆机构故障诊断研究

针对因历史故障数据不足,缺少规范的故障数据收集机制和成熟的质量监测管理技术手段,大型复杂机电液系统性能状态难以准确评估的问题,以发射塔电缆摆杆作为典型机构,研究并提出了一种基于数字孪生技术的故障诊断方法。该方法以数字孪生系统“五维模型”理论为基础,构建了摆杆系统数字孪生架构体系;运用UG软件,通过几何运动学和动力学建模,建立了虚拟仿真模型,设计了基于ADAMS和Matlab联合仿真的数字孪生系统。该系统通过仿真信号与实测信号的对比,表明其对于物理实体的模拟仿真精度可达96%。最后,通过典型喘行故障试验,修改虚拟模型有关参数进行仿真,验证基于数字孪生体对摆杆机构故障诊断的有效性,以及利用其论证维修改进方案的可行性。

使用工况条件下核用18Ni(300)钢拉杆的力学性能

研究了由时效热处理18Ni(300)钢制作拉杆的显微组织,以及使用工况条件下拉杆的室温循环加载力学性能和断口形貌,分析了拉杆的断裂模式。结果表明:经过固溶处理的18Ni(300)钢呈现淬火马氏体组织,原奥氏体晶粒尺寸约为24μm,残余奥氏体面积分数约为0.26%;时效处理后,原奥氏体晶粒尺寸约为26μm,未观察到残余奥氏体;18Ni(300)钢马氏体发生回复,(Ni,Co,Fe)3Ti相在位错上析出。模拟安装使用工况条件下,室温循环加载后拉杆试样的循环断裂周次均大于480次,断裂部位主要分布在拉杆螺纹根部;断口由塑性变形区和脆性变形区组成,塑性变形区居中;断面以拉伸断裂特征为主,以疲劳断裂特征为辅,由此推断拉杆主要受轴向拉伸的作用。

基于有限元的行程可调液压油缸活塞杆断裂力学性能测试

设计基于有限元的行程可调液压油缸活塞杆断裂力学性能测试方法。以行程可调液压油缸断裂的活塞杆为研究对象,采用有限元分析软件构建液压油缸活塞杆有限元模型。从宏观形貌、拉伸性能、硬度及粗糙度等方面,测试了行程可调液压油缸活塞杆的断裂力学性能。结果表明:经过拉伸和硬度测试发现,试件的弹塑性较差;粗糙度变大是导致行程可调液压油缸活塞杆发生断裂的主要原因;断裂试件的纵向残余应力变化较大,断裂后为504 MPa。

埋弧焊丝用H08Mn钢盘条氧化铁皮研究及其轧制工艺

H08Mn钢盘条多用于制作埋弧焊丝,其表面的氧化铁皮对拉拔前机械除鳞效果有明显影响。介绍了盘条氧化铁皮的形成机制、氧化铁皮的种类和构成;采用不同的工艺参数,包括始轧温度、精轧温度、吐丝温度和首道辊速度,轧制了H08Mn钢盘条,随后检测了盘条氧化铁皮的厚度、盘条的晶粒度和抗拉强度。结果表明:采用这样的工艺参数即880℃的精轧温度、900℃的吐丝温度和18 m/min(按5%递增)的首段辊道速度轧制的H08Mn钢盘条,其氧化铁皮厚度小于20μm且易剥落,晶粒度和抗拉强度均有利于后续拉拔加工。

肥料装车机凸轮连杆式码包机构的优化设计

针对目前袋装肥料装车机中存在码包过程丢包倾斜、溜包等问题,提出了一种凸轮连杆组合式码包机构。首先建立运动数学模型,对其进行了运动学特性分析,并根据码包机构的运动数学模型建立相应的ADAMS参数化模型,通过改变优化模型中设计变量的参数,得到设计变量对码包机构工作效果的影响规律,最后利用MATLAB中的遗传算法对码包机构设计变量进行优化设计,求解得出一组最优尺寸参数。通过对比优化前后码包机构的仿真曲线以及制作样机试验,验证优化后的码包机构作业时同步性和平稳性均达到设计要求。

矿井锚杆腐蚀研究综述:因素、机理及防腐技术

锚杆是巷道支护体系中最基本的组成部分,其力学特性易受矿井环境影响。为保障巷道支护安全,减缓锚杆腐蚀失效进程,有必要对矿井腐蚀环境下的锚杆腐蚀因素、腐蚀机理及防腐技术进行研究。采用典型调研、数据统计、理论分析等手段剖析了矿井腐蚀环境下锚杆腐蚀主要影响因素,阐述了锚杆电化学腐蚀机理、点蚀形核生长机理以及应力腐蚀开裂机理,介绍了原材料防腐技术、表面防腐技术和防腐支护体系特点,指出单因素分析向多因素分析、宏观研究向微观研究、理论型向实用型转变是锚杆防腐技术研究的重要发展方向。