基于有限元的组合式臂架等效惯性矩计算方法研究

提出基于有限元的组合式臂架等效惯性矩的计算方法,将变刚度组合构件的稳定性计算转化成等刚度构件的等效计算,由此推算出组合构件的等效欧拉临界载荷,得出的屈曲稳定性系数理论数值与有限元屈曲分析得出的屈曲系数相一致,并通过现场试验测试,验证本计算方法的正确性。     

套管柱载荷数学模型分析

通过对特殊螺纹套管现场下井监督指导、跟踪调查,获得了四川地区套管的主要受力情况。对套管柱井内载荷计算数学模型的对比分析,指出适合西南油气田不同井可以采用不同的载荷数学模型进行套管强度设计,从而为不同区块施工井提供相配套的套管,降低套管失效事故的发生。     

低温环境下波纹管的轴向刚度计算

应用有限元软件Ansys建立波纹管的有限元分析模型,又通过对U型波纹管轴向刚度计算经验公式的温度修正,计算室温和低温(直到-253 ℃)状态下波纹管的轴向刚度,并对波纹管刚度与壁厚、波高、波距等波形参数之间的相关性进行数值计算.波纹管的性能与结构设计的波形参数密切相关,对不同用途或不同控制因素的波纹管,波形参数的确定应有侧重点,且需综合考虑.通过与文献中的实验结果对比得知,用材料弹性模量温度系数对经验公式进行修正是有效的.     

金属磁记忆检测在钻具评价中的应用

在钻井过程中,钻具在井下承受着复杂的交变应力的作用,经过一段时间的使用后则会产生破坏,这给钻井生产带来巨大的经济损失.因此开展钻具适用性评价方法研究不仅具有理论意义,而且有重大的实际意义.本文主要讨论的是利用无损检测技术,提出一种适合于钻井现场使用的钻具适用性评价方法,用以评价在役钻具的使用状况,检测出不能继续使用的钻具,从而有效避免井下钻具事故的发生.为此本文将磁记忆检测用于钻具的失效分析,通过理论推导与现场实验建立了钻具磁记忆检测信号与应力集中系数的实验关系.利用R.E.Peterson提出的疲劳缺口系数公式对钻具的无损评价进行了初步尝试,现场实验表明该方法对钻具的评价具有指导意义.     

周向均布拉杆转子接触段刚度特性研究

为了研究存在大量轮盘结合面的燃气轮机拉杆转子的刚度特性,以轮盘间通过粗糙平面连接的周向均布拉杆转子为研究对象,建立其整体刚度的理论计算模型并定义了结合面刚度无量纲因子;运用三维有限元法对转子接触段进行考虑非线性接触的静力分析,计算了接触段刚度修正系数、接触应力分布状态、拉杆刚度比例系数以及拉杆应力随刚度无量纲因子的变化关系,计算结果表明刚度无量纲因子λ=1是转子整体应力应变状态保持稳定的临界值。研究可为周向拉杆转子预紧力的确定提供参考。     

基于有限元的碟簧静刚度研究

提出一种基于有限元技术的组合碟簧的静刚度研究方法。针对一种碟簧的组合建立有限元模型并用此种碟簧组合的实验测试数据对模型进行修正,从而得到正确可用的有限元模型。将正确的有限元模型应用于不同的碟簧组合形式并进行仿真计算得到碟簧在不同的组合形式下的静刚度曲线。     

上扣扭矩对储气井疲劳性能的影响

储气井是一种受交变压力载荷的高压储气设施,其分段的套管通过螺纹和接箍连接,这种螺纹连接的上扣扭矩影响螺纹结构的应力,进而影响储气井的疲劳寿命.建立了储气井套管和接箍螺纹连接的有限元模型,讨论了储气井上扣扭矩的计算方法及其对储气井疲劳性能的影响,并得出以下结论:上扣扭矩对于储气井内部应力分布具有较大影响,计算中不能被简单忽略;预紧力作用下,储气井套管内整体应力水平高于外部接箍,但最大应力却发生在接箍上;对于套管和接箍结构,最易发生疲劳破坏点是套管第一个整螺纹齿齿根或套管与接箍贴合处的螺纹齿齿根部;上扣扭矩没有改变套管和接箍处应力集中点的应力幅值,对储气井的疲劳特性影响较小.     

基于拉力带参数的IST-LEJ设计与分析

提出了一种新型结构柔性铰链,命名为平面折展抗拉压倒置扭转铰链(Inverted stripe-type torsional lamina emergent joint,IST-LEJ),设计了该铰链的结构形式,推导了其弯曲等效刚度计算公式,提出了基于拉力带特征参数的修正系数。通过实例的理论计算和有限元仿真分析,验证了基于修正系数的弯曲等效刚度公式的正确性。通过不同拉力带尺寸的实例计算,进一步验证了等效刚度理论公式的正确性和修正系数的有效性。建立了与IST-LEJ设计实例外形尺寸和特征参数相同的平面折展倒置扭转铰链(Inverted torsional lamina emergent joint,IT-LEJ)铰链的有限元模型,比较了IST-LEJ与IT-LEJ铰链的弯曲性能和抗拉压性能。最后,对聚丙烯和铍青铜材料的这两种铰链进行了失效分析,得出了不同材料铰链各自的弯曲变形范围。     

含弹性杆件的并联机器人刚度分析

通过分析包含弹性杆件的并联机器人的刚度系数的性质,计算了机器人在各方向上的刚度,绘制了最小刚度系数的变化曲线,研究了刚度与奇异位形、机器人的固有频率及弹性振动振幅的关系.计算实例表明,刚度系数和奇异位形、机器人的固有频率有密切的联系,可用于预测含弹性杆件的并联机器人的弹性动力学特性和响应,不需要进行弹性动力学计算,计算时间节省94%.     

微结构参数对静压气体导轨节流系数和转动刚度的影响

小型复合节流静压气体导轨是保证光刻机高速运动和精确定位的关键部件.为提升导轨的承载力及刚度,在工作面常增加浅腔和沟道等微结构,但微结构对导轨的力学特性、特别是转动刚度的影响一直不清晰.采用网络自适应方法研究了微结构的四个主要参数的影响,以此为依据归纳拟合出修正节流系数,建立了带有修正节流系数的导轨性能半解析模型,揭示了微结构参数微米量级变化对导轨性能的影响规律.以转动刚度最优、兼顾承载力和刚度为原则,归纳了各微结构参数的选取表达式,用于指导同类型静压气体导轨的设计.以光刻机可变狭缝系统为例,采用提出的修正节流系数及微结构选取方法对下层导轨进行设计.试验表明,转动刚度达到10.3× 103N·m/rad,可以满足高速可变光阑加速扫描运动的需求,验证了方法的准确有效性.     

锥蜗杆副装配条件的探讨

通过锥蜗杆传动副的啮合分析,用当量圆柱蜗杆副的分析方法,得出阿基米德锥蜗杆副的装配条件。     

随钻扩眼工具的研究与优化

随钻扩眼技术在处理井下复杂情况、降低钻井综合成本、提高固井质量等方面具有显著的优势,随钻扩眼工具正逐渐成为一种重要的石油钻井配套工具.基于随钻扩眼技术优势的分析,本文介绍了双心扩眼钻头和偏心式、同心式随钻扩眼工具的结构原理、性能特点和应用情况,同时也对近年来国外新型井下扩眼工具的一些先进技术进行了分析.文章提出应加强现有工具的适应性和匹配性研究,发掘各类工具的优势.优化执行机构、扩眼总成和水力机构,重视底部钻具组合力学特性的分析是今后发展和完善随钻扩眼工具及技术的几个重要内容.     

井下水力涡轮的研究现状及发展

石油开采过程中,井下水力涡轮作为动力单元在各种先进钻采设备、仪器、工具中得到了广泛应用并迅速发展。介绍了井下水力涡轮的常见型式与特征,总结了常用的设计方法及特点,重点介绍了水力涡轮在井下动力钻具和井下泥浆涡轮发电机的应用现状,并对水力涡轮的制造作了概述。最后指出,努力实现技术自主创新,打破国外技术垄断,对于我国井下设备和仪器的发展具有非常重要的意义。     

An experimental rig for near-bit force measurement and drillstring acoustic transmission of BHA

An experimental rig for near-bit force measurement and drillstring acoustic transmission of bottom-hole assembly (BHA) is designed and implemented to investigate downhole dynamic behaviors of BHA. By using a developed dynamic force sensor device with a four-straight beam strain gauge, the rig can measure axial, lateral forces and torques exerted on simulated drillstring while rotating. For the upward transmission of downhole dynamic force data, drillstring acoustic telemetry method is further analyzed by transient numerical simulation. Considering acoustic signal attenuation and transmissibility, a narrow pulse on-off keyed modulated time-delay signal transmission method is developed. The near-bit force measurement experiments of BHA are performed under different weight on bit loads, deviation angles and drill pipe combinations. The obtained force data are transmitted via acoustic waves propagating along the simulated drillstring. The results show that acoustic transmission rate is approximated 77 bit/s along 6.4-m simulated drillstring under 1-W power excitation in the laboratory.     

高压差越孔密封技术

油田井下滑套类工具普遍存在高压差下越孔密封的技术难题.为了保证滑套能够反复越孔后仍能可靠密封,分析了压力平衡式、双密封圈组合式和异形密封圈3种越孔密封技术的结构和特点,并进行了试验研究.结果表明,这3种技术满足从一次性越孔密封到长期频繁越孔密封的不同要求,基本满足当前油田井下工具对高压差越孔密封的需要.其中压力平衡式越孔密封技术满足长期频繁越孔密封的要求,双密封圈组合式越孔密封技术满足密封次数少于5次的密封要求,而异形密封圈越孔密封技术适用于要求一次性高压差越孔密封的场合.     

Design and Analysis of an Active Helical Drive Downhole Tractor

During oil-gas well drilling and completion,downhole tools and apparatus should be conveyed to the destination to complete a series of downhole works.Downhole tractors have been used to convey tools in complex wellbores, however a very large tractive force is needed to carry more downhole tools to accomplish works with high efficiency. A novel serial active helical drive downhole tractor which has significantly improved performance compared with previous work is proposed. All previously reported helical drive downhole tractors need stators to balance the torque generated by the rotator. By contrast, the proposed serial downhole tractor does not need a stator; several rotator-driven units should only be connected to one another to achieve a tractive force multifold higher than that was previously reported. As a result,the length of a single unit is shortened, and the motion flexibility of the downhole tractor is increased. The major performance indicators, namely, gear ratio, velocity, and tractive force, are analyzed. Experimental results show that the maximum tractive force of a single-unit prototype with a length of 900 mm is 165.3 kg or 1620 N. The analysis and experimental results show that the proposed design has considerable potential for downhole works.     

深水全电控智能完井工艺研究

深水开发井修井费用高,作业难度大。面对越来越突出的层间矛盾,常规的合采方式已经无法满足生产需求。开发了一种适用于深水的全电控智能完井工艺,该工艺采用全电控方式,通过电缆控制井下调控工作筒,实现了井下温度、压力、流量等信号的实时测试及井下产液量的实时调整。有效地降低了调控作业费用,提高了调控效率,降低了层间矛盾,有利于整体采收率的提高。对深水开发模式下电信号的传输进行调研与研究,通过脐带缆终端设备(UTA)、水下采油树控制模块(SCM模块)、采油树穿越装置等关键设备,实现了深水开发井智能完井的信号传输。     

虚拟现实环境下产品装配定位导航技术研究

基于自由度归约方法进行约束分析，在理解与识别设计者的装配操作和意图基础上，通过空间几何角度分析，根据装配关系建立装配约束关系树，实现了虚拟现实环境下的产品装配的定位导航，该方法在汽车发动机的虚拟装配中得到了较好的应用。     

Stress analysis of lead-free solders with under bump metallurgy in a wafer level chip scale package

The wafer level chip scale assembly (WLCSP) has increasingly become popular due to its compact, wafer scale assembly. In a WLCSP assembly, the under bump metallurgy (UBM) connecting the solder joints and the chip is crucial for the assembly reliability. This study focuses on a WLCSP with 96.5Sn3.5Ag/95.5Sn3.8Ag0.7Cu solder joints and Ti/Cu/Ni UBM on a 2–layer microvia build-up electric board. Furthermore, the Garofalo-Arrhenius creep model in finite element analysis ANSYS 6.0 is used for simulations on the WLCSP assembly under thermal cycling to investigate the deformations of the assembly with different thickness of nickel layer, the maximum equivalent strain and maximum equivalent stress of microvias/joints. Finally, the Coffin-Manson equation is applied to predict the fatigue lives of four combinations of solder joints with different eutectic alloy and thickness of nickel layer.     

Non-linear torsional vibration characteristics of an internal combustion engine crankshaft assembly

Crankshaft assembly failure is one of the main factors that affects the reliability and service life of engines.The linear lumped mass method,which has been universally applied to the dynamic modeling of engine crankshaft assembly,reveals obvious simulation errors.The nonlinear dynamic characteristics of a crankshaft assembly are instructionally significant to the improvement of modeling correctness.In this paper,a general expression for the non-constant inertia of a crankshaft assembly is derived based on the instantaneous kinetic energy equivalence method.The nonlinear dynamic equations of a multi-cylinder crankshaft assembly are established using the Lagrange rule considering nonlinear factors such as the non-constant inertia of reciprocating components and the structural damping of shaft segments.The natural frequency and mode shapes of a crankshaft assembly are investigated employing the eigenvector method.The forced vibration response of a diesel engine crankshaft assembly taking into account the non-constant inertia is studied using the numerical integral method.The simulation results are compared with a lumped mass model and a detailed model using the system matrix method.Results of non-linear torsional vibration analysis indicate that the additional excitation torque created by non-constant inertia activates the 2nd order rolling vibration,and the additional damping torque resulting from the non-constant inertia is the main nonlinear factor.The increased torsional angular displacement evoked by the high order excitation torque relates to the non-constant inertia.This research project is aimed at improving nonlinear dynamics theory,and the confirmed nonlinear parameters can be used for the structure design of a crankshaft assembly.