封隔器密封胶筒的尺寸优化

封隔器参数的选取对其工作性能至关重要,合理选择胶筒的形状尺寸可有效避免因应力集中、残余变形而导致的密封失效或起出困难。讨论了密封胶筒端面倒角、胶筒长度对接触应力的影响,进而分析两者对胶筒密封性能的影响。结果表明,40°~50°区间的倒角有助于提高胶筒与套管内壁之间的接触应力;增加密封胶筒长度,会造成接触应力下降。     

扭转载荷对压裂用封隔器胶筒密封性能的影响

利用有限元分析软件建立封隔器胶筒模型,分析单一轴向载荷和轴向、扭转载荷共同作用下,胶筒与套管之间的接触应力及其沿轴向的分布规律,最大接触应力随胶筒端面角、子厚度、筒高3个结构参数和摩擦因数的变化,以及施加不同扭转载荷时对胶筒密封性能的影响。研究结果表明:在单一轴向载荷作用下,最大接触应力随倾斜角度增大先减小后增大,随子厚度的增加先增加后减小,随筒高的增加而减小,随摩擦因数增大先减小后增大;施加扭转载荷后,不同端面角、子厚度、筒高下胶筒的最大接触应力整体降低且波动较大,随摩擦因数增大胶筒接触面之间的摩擦力增大,加速了胶筒磨损和老化;不同扭转载荷作用下胶筒最大接触应力值波动较大,导致密封性能不稳定。因此,扭转载荷使得胶筒密封性降低,导致最大接触应力波动较大,使胶筒的密封性能存在不稳定性。     

悬挂式封隔器密封胶筒的密封性能研究

根据悬挂式封隔器密封胶筒的结构和工作特点,分析封隔器在初封和工作阶段胶筒的密封原理及其相应的自由变形、约束变形和稳定变形3种状况下的密封特性。建立胶筒密封性能分析的理论模型,应用压力法分析胶筒在约束变形和稳定变形阶段的材料、几何和应力变化等非线性关系,得出密封面接触应力分布的计算模型,并确立应用封隔器胶筒密封面接触应力判断胶筒密封性能的判别准则。建立悬挂式封隔器胶筒密封的有限元模型,有限元仿真与数值计算得到的密封面接触压力的大小和分布形状具有较好的一致性,证明了建立的理论模型的有效性。     

封隔压差与间隙对封隔器胶筒性能的影响

为探讨封隔压差和封隔间隙对封隔器胶筒封隔性能的影响,应用有限元分析软件,研究不同封隔压差和间隙下胶筒的Von Mises应力分布、胶筒与套管壁间接触应力的分布以及胶筒的变形情况。结果表明:随着封隔压差的增大,胶筒上端部的Von Mises应力值不断增大,胶筒失效的可能性增加,但胶筒与套管壁的接触应力值增大,胶筒的封隔能力增强;随着封隔间隙的增大,胶筒上端Von Mises应力值增大,胶筒剪切失效的可能性增加,且胶筒与套管壁的接触应力减小,胶筒的封隔能力下降。设计出一种蜗形状防突装置,分析其对胶筒封隔性能的影响。结果表明:蜗形保护环能有效地防止胶筒端部突出,且胶筒的应力分布更均匀,胶筒与套管壁间的接触应力值更大,提高了胶筒的封隔能力。     

封隔压差与间隙对胶筒的性能影响研究

为探讨封隔压差和封隔间隙对封隔器胶筒封隔性能的影响,应用有限元分析软件,研究不同封隔压差和间隙下胶筒的Von Mises应力分布、胶筒与套管壁间接触应力的分布以及胶筒的变形情况。结果表明：随着封隔压差的增大,胶筒上端部的Von Mises应力值不断增大,胶筒失效的可能性增加,但胶筒与套管壁的接触应力值增大,胶筒的封隔能力增强;随着封隔间隙的增大,胶筒上端Von Mises应力值增大,胶筒剪切失效的可能性增加,且胶筒与套管壁的接触应力减小,胶筒的封隔能力下降。设计出一种蜗形状防突装置,分析其对胶筒封隔性能的影响。结果表明：蜗形保护环能有效地防止胶筒端部突出,且胶筒的应力分布更均匀,胶筒与套管壁间的接触应力值更大,提高了胶筒的封隔能力。     

压缩式封隔器异型胶筒密封性能分析

为了提高油田分层开采特别是非常规油气完井技术中使用的封隔器常规胶筒的密封性能,使其应力分布更均匀,通过在胶筒与中心管接触一侧的中间开设小圆槽,设计出几种具有不同半径小圆槽的异型胶筒。采用非线性有限元方法,利用 ANSYS 分析软件建立封隔器胶筒有限元模型,对比分析常规胶筒和异型胶筒的密封性能,并研究圆槽半径对封隔器密封性能的影响。结果表明：异型胶筒最大接触应力明显高于常规胶筒,且接触应力分布均匀,因此其密封性能高于常规胶筒;在一定范围内,圆槽半径对接触应力影响不大,但圆槽半径过大会降低封隔器的密封性,应根据现场实际情况来确定圆槽半径。     

封隔器胶筒密封性能影响因素分析

利用罚函数法将接触面约束条件引入势能泛函,建立封隔器胶筒有限元方程,采用Newmark法进行数值求解,分析封隔器胶筒几何参数和物理参数对封隔器密封性能的影响。研究结果表明:胶筒与套管间接触压力随胶筒长度的增加而增大,这种增长趋势在胶筒长度达到一定数值后趋于减缓;胶筒与套管间接触压力随胶筒厚的增加而增大,而压缩变形随胶筒厚度增加而逐渐减小;胶筒的材料参数设计要求在满足密封要求的前提下,选择较大的胶筒材料系数。     

压缩式胶筒结构优化及裸眼密封性能分析

压缩式封隔器广泛用于油田分层开采工艺，其胶筒的坐封通过高压流体作用在活塞上压缩胶筒或管柱来实现。现场作业发现：压缩式胶筒离载荷端较远，且大多采用单向加载，导致坐封不完全，接触应力与密封性能系数较低。针对上述问题，基于Mooney-Rivlin超弹模型、胶管变形及接触非线性理论，建立压缩式胶筒组有限元计算模型,从内衬套和防肩突结构开展单因素分析，并对其裸眼密封性能进行研究，结果表明：三角形内衬套能有效提高胶筒中部接触应力；金属圆环防突结构能提高胶筒密封性能系数；与常规压缩式封隔器相比，优化后的压缩式封隔器密封性能显著提高；裸眼井壁的不规则程度在一定范围内时，对封隔器的密封性能影响不大。     

封隔器胶筒接触应力的有限元分析

通过实测封隔器胶筒所用橡胶材料的应力应变数据，在ANSYS有限元分析软件中用超弹性本构模型对实验数据进行拟合，通过比较选择了能更精确描述封隔器胶筒的应力应变关系的Yeoh模型，进而对封隔器压缩式胶筒的接触应力进行了数值模拟，得到接触应力沿轴向的分布情况。     

双向压缩式新型封隔器密封性能研究

针对常规封隔器存在的接触应力分布不均匀、胶筒密封不实等问题,提出一种双向压缩式封隔器。该封隔器采用组合结构胶筒的形式,并采用在胶筒两侧同时对向均匀压缩的新型加载方式。采用ANSYS软件建立双向压缩封隔器胶筒有限元模型,研究分析该新型封隔器的密封性能,并与常规封隔器进行比较。结果表明:双向压缩式封隔器胶筒平均接触应力明显高于常规胶筒(高20%左右),接触区域更大,接触区域上的接触应力分布更均匀,胶筒的变形稳定,密封性能更好。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.