球形防喷器胶芯失效分析

球形防喷器胶芯是井控设备中的易损件,弄清胶芯的失效形式和原因对于提高其使用寿命和可靠性具有重要意义。根据球形防喷器的工作原理,分析胶芯在几种典型工况下的受力与变形规律;结合现场使用情况,总结出胶芯的主要失效形式有:胶芯上表面开裂和层块状脱落;胶芯内壁大块脱胶;胶芯底部与活塞接触处橡胶开裂;胶芯不能密封住井底高压流体;封井后胶芯不能及时恢复等。综合分析上述各种失效形式后,认为提高球形防喷器胶芯的密封可靠性和性能,应主要从胶芯材料和结构方面入手,即应优化胶芯和支撑筋的结构形状和尺寸,降低胶芯中的峰值应力;应改进胶芯橡胶材料配方和硫化工艺,提高橡胶的抗拉性能、扯断永久伸长率、耐油性能、抗老化性能等。     

基于实验的旋转控制头胶芯密封面寿命优化

欠平衡钻井起下钻过程中,旋转控制头胶芯受到交替循环载荷易发生疲劳失效。首先对旋转控制头的密封原理进行分析,得出了动态密封过程中胶芯的受力情况。然后对胶芯材料进行拉伸试验,确立了变形过程中Yeoh本构模型。再应用Abaqus软件建立了胶芯动态密封有限元模型,进行了起下钻过程中胶芯密封过程的模拟以及影响胶芯密封面疲劳寿命的因素进行了优化分析。对胶芯内径进行了优化,对不同外径钻杆应搭配的胶芯内径尺寸进行优化,得到了常用钻杆最优的钻杆胶芯组合。还对不同井口压力作用下钻杆下放和上提速度进行了优化,井压越大越容易造成胶芯疲劳失效,得出了不同压力条件下钻杆的安全下放和上提速度。最后按照中国标准在中国国家石油工业井控设备质量监督检验中心进行了室内密封试验以及现场应用试验证实了有限元优化的可靠性,对提高胶芯使用寿命和油田作业安全具有重要现实意义。     

旋转控制头密封胶芯性能三维有限元分析与结构优化

为提升带压起下钻过程中旋转控制头胶芯密封性能,基于虚功原理得到动态密封过程的有限元控制方程,并进行橡胶单轴压缩试验确立胶芯变形过程中的Yeoh本构模型;运用ABAQUS试验平台建立胶芯三维有限元模型,通过模拟起下钻过程中胶芯动态密封过程,得出密封面上受力分布规律;研究胶芯内锥角、外锥角、内径等结构参数对密封性能的影响....     

带压作业闸板防喷器胶芯磨损行为研究

针对带压作业时闸板防喷器胶芯的耐磨块易发生磨损导致密封失效和起下旧管柱时其工作寿命较小等问题,对带压作业过程中闸板防喷器胶芯磨损行为进行研究。以某油田现场使用的闸板防喷器胶芯为对象,从微观角度分析带压作业过程中胶芯耐磨块主要磨损机制和表面粗糙度对耐磨块磨损机制的影响;利用有限元软件建立胶芯动静密封模型,从宏观角度分析不同工况和摩擦因数对闸板胶芯密封性能及耐磨块磨损规律的影响。结果表明:带压作业过程中耐磨块主要磨损机制为磨粒磨损和疲劳磨损,管柱的粗糙度越大,耐磨块磨损越严重;井筒压力造成的胶芯上部应力集中是耐磨块上部磨损严重的主要原因;管柱与耐磨块圆弧面间的摩擦因数应控制在0.1以内,否则会加速耐磨块的磨损。     

封井后提放钻杆过程中球形防喷器胶芯力学行为*

球形防喷器封井后强行起下钻作业极易导致胶芯密封失效,为研究动密封过程中防喷器胶芯失效机制,基于橡胶大变形理论建立球形防喷器动态密封数值模型,探究球形防喷器胶芯在封井和起下钻过程的应力分布和失效模式。结果表明：球形防喷器密封钻杆后,胶芯内壁会产生条状褶皱,支撑筋下板块拐角处产生鼓点状应力分布,颈部和背部存在应力集中现象;当钻杆倾斜时,钻杆与胶芯接触密封区也发生倾斜,胶芯左右两侧应力小幅增大;起下钻过程中,胶芯内壁的条状应力集中变为片状分布,钻杆接头进出密封区域时,接触应力发生突变。     

气控环形防喷器密封胶芯大变形分析

针对气控环形防喷器胶芯在密封过程中的大变形以及与油管存在密封压力难以计算的问题,建立胶芯物理模型,结合厚壁筒理论与橡胶本构方程,同时考虑胶芯的材料非线性和几何非线性,探讨防喷器密封过程中胶芯变形与接触压力的变化。根据胶芯变形过程中无变形阶段、自由变形阶段和接触变形阶段的不同受力状况,利用迭代的方法对每个离散微段施加控制压力,得到不同控制压力下胶芯变形量与接触压力,并与仿真结果进行比较。结果表明:在自由变形阶段,随控制压力增加,胶芯变形量逐渐增大且由中间向两侧逐渐减小;在接触变形阶段,胶芯内径保持不变,且与油管间接触压力不断增加。采用胶芯变形理论方法计算的接触压力变化规律与仿真结果基本相同,验证了胶芯变形理论计算方法的正确性。     

钢丝缠绕予应力高压容器和冷挤压凹模在内压作用下内壁不出现拉应力的设计原理

钢丝或钢带缠绕予以应力高压容器或模具由芯筒和缠绕层两部分组成。缠绕层采用等剪应力方法充分利用了钢丝的强度,比采用等张或等切应力方法能承载更大的工作内压。芯筒多采用高强材料。为使芯筒不易开裂并提高疲劳寿命,要求在工作内压载荷下内壁不出现拉应力。本文提出满足这一要求的最佳设计方法和计算公式。     

飞机结构损伤光固化复合材料疲劳寿命研究

疲劳裂纹的萌生和扩展是材料在变载荷作用下的主要失效形式.试验针对飞机光固化复合材料修理补片的疲劳寿命进行了测试,并考核了不同修理工艺(半宽度胶接、全宽度胶接及铆接修理)试样的疲劳寿命,为确定最佳修理工艺提供了试验依据.     

飞机结构损伤光固化复合材料疲劳寿命研究

疲劳裂纹的萌生和扩展是材料在变载荷作用下的主要失效形式。试验针对飞机光固化复合材料修理补片的疲劳寿命进行了测试，并考核了不同修理工艺（半宽度胶接、全宽度胶接及铆接修理）试样的疲劳寿命，为确定最佳修理工艺提供了试验依据。     

冷镦钢球用硬质合金模具的失效分析

通过对硬质合金模具失效形式与使用寿命的关系的调查及对合金模芯的疲劳断口形貌、合金低倍与高倍组织的检测,认为在模具失效的多种形式中,疲劳断裂是主要的。要提高硬质合金模具的使用寿命,必须提高硬质合金的抗疲劳韧性,提高材料的冶金质量。附图8幅,表2个。     

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.     

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....     

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。     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.