API圆螺纹油管接头连接性能的非线性有限元分析

ＡＰＩ圆螺纹油管在油田有着广泛的应用，在使用过程中，发现油管接头有粘扣甚至滑脱现象。为了探讨ＡＰＩ圆螺纹接头粘扣和滑脱的机理，改善螺纹接头的连接性能，对螺纹接头在机紧过盈，轴向拉伸载荷作用下进行计算机仿真的非线性有限元分析。分析结果表明，啮合螺纹接触应力过高造成螺纹粘扣；管体螺纹接头部分强度刚度较低限制了螺纹接头的连接强度。     

API套管圆螺纹接头粘扣失效分析

粘扣是套管接头的失效形式之一，它发生在套管上扣操作过程中的螺纹处。套管一旦发生粘扣，直接影响到套管柱的密封性能和连接强度。通过对套管接头的上卸扣实验和接头螺 凶数值计算，对套管产生粘扣的原因进行了研究，并利用摩擦磨损机理，描述了粘扣的产生过程。     

宝钢钻井用套管实物性能试验研究

针对套管在钻井过程中受到不同程度磨损的情况,模拟套管均匀磨损和偏磨工况,采用全尺寸实物试验方法,对宝钢Φ139.7×9.17 mm P110钻井用套管进行了拉伸失效和静水压试验研究。研究结果表明:宝钢钻井用套管,在上、卸扣试验中螺纹和密封面未发生黏着磨损,拉伸失效载荷大于API BUL 5C2规定接头连接强度最小值17.7%,失效内压值大于API BUL 5C2规定最小内屈服强度46.7%。对该产品进行了钻井试验,完成油层套管钻井井深1 160 m,满足了油田使用要求。     

石油套管螺纹失效形式原因分析

目前石油套管连接螺纹主要采用两种基本扣型,即偏梯型和圆弧型套管螺纹。其失效形式基本相同。螺纹在使用连接过程中,一但失效其连接强度大幅下降,(出现掉井现象)。     

油套管螺纹接头的发展

接头是油套管产品的重要组成部分之一,也是石油、天然气开采中油套管柱中最薄弱的环节。接头的实体性能、使用性能和经济性是油套管主要指标。介绍了国内外油套管接头的发展:从最初API圆螺纹、长圆螺纹、偏梯形螺纹接头到各个厂家推出的具有各项突出性能的特殊螺纹接头,再回归到具有实用性的经济型油套管接头。介绍了具备密封完整性、结构完整性和重复上卸扣完整性的经济型气密封油套管接头的开发与进展。     

油套管螺纹连接抗粘扣技术的研究现状及展望

螺纹粘扣作为油套管中最常见的失效形式，一直是国内外冶金和石油系统的研究重点。对油套管粘扣现象作了简单的解释，通过对国际上近20年来油套管螺纹连接抗粘扣技术研究情况的分析总结，归纳了各种关于管螺纹粘扣失效的机理研究、管螺纹参数优化及其检测研究、螺纹脂和螺纹镀层的研究、油套管特殊螺纹连接的研究、油套管上卸扣的操作规范的研究，介绍了其主要研究成果，指出存在的问题，并探讨了进一步开展研究的方向。     

API偏梯形套管螺纹连接的接触应力场研究

随着油气田勘探开发向纵深发展 ,对偏梯形螺纹套管的需求量越来越大 ,深入研究此种套管螺纹连接力学性能显得非常重要。在分析套管螺纹粘扣机理的基础上 ,建立了 API J5 5194 .1m m× 8.33mm偏梯形套管螺纹连接的非线性接触模型 ;研究了此种套管接头在上紧扭矩、拉应力、压应力以及摩擦力等不同载荷作用下内外螺纹接触应力的分布状态 ;同时对内外螺纹锥度的极限配合情况进行了数值模拟 ,并就摩擦因素和锥度对偏梯形螺纹连接应力场分布的影响进行了总结。     

API圆螺纹套管接头上卸扣力学性能实验研究

为了深入了解上卸扣工况对套管接头力学性能的影响,给研究套管接头产生粘扣的力学因素提供实验依据,采用在套管接 头内外表面巾应变片的方法,利用全尺寸上卸扣试验机,对套管接头进行了重复上卸扣实验,测量了接头内外表面应变和上卸扣扭矩。通过实验结果分析,确定了影响接头粘扣的主要力学条件和部件,所确定部件与实际操作过程发生粘扣部件相吻合,采用增大接箍螺纹端部锥度,降低端部接触压力的方法,提高了套管的抗粘扣性能     

快速上扣螺纹接头的有限元分析及优化设计

快速上扣螺纹接头是一种适用于大口径套管的接箍螺纹连接方式,具有对扣容易、上扣效率高、不错扣的特点,特别适合于海上等恶劣环境作业.根据市场需求,宝钢开发出了自主知识产权的快速上扣螺纹接头.介绍了宝钢快速上扣螺纹接头的优化设计过程,利用有限元方法对齿形角、螺纹中径、锥度、连接强度等进行分析,确定了接头的优化结构.开发的快速上扣螺纹接头产品分别在宝钢实验室和西安管研院完成并通过了全尺寸实物性能试验,13.375 in规格已在油田完成下井试验,证明产品的上扣完整性、密封完整性、结构完整性满足油田使用要求.     

套管圆螺纹连接密封性能影响因素分析

详细分析了影响套管圆螺纹连接密封性能的因素,指出了圆螺纹连接存在的泄漏间隙的特点,从理论上揭示了螺纹脂密封机理及基面中径,锥度,螺距累积误差所起的重要作用,另外还对上扣扭矩和留数对密封性能的影响作了简要分析。     

Insertional torque and pull-out strengths of conical and cylindrical pedicle screws in cadaveric bone

STUDY DESIGN: Insertion torque and pull-out strengths of conical and cylindrical pedicle screws were compared in human cadaveric vertebral bodies. OBJECTIVES: To compare the performance of the conical design with the cylindrical design, and to determine whether insertional torque correlates with pull-out strength. SUMMARY OF BACKGROUND DATA: A tapered pedicle screw design may lessen the likelihood of implant failure. Its effect on thread purchase is not known. Previous studies of cylindrical designs on the relation between insertion torque and pull-out strength have been conducted in bovine and synthetic bone. METHODS: Seventy-eight pedicles were assigned randomly to one of the following pedicle screw: Texas Scottish Rite Hospital (Sofamor-Danek, Memphis, TN), Steffee VSP (Acromed, Cleveland, OH), Diapason (Dimso, Paris, France), AO Schanz (Synthes, Paoli, PA), or Synthes USS (Synthes, Paoli, PA). Pedicle screws were inserted with a torque screwdriver. Each screw was extracted axially from the pedicle at a rate of 1.0 mm/sec until failure using an MTS machine (Bionix 858, Minneapolis, MN). Force data were recorded. RESULTS: The conical design had the highest insertion torque. There were no significant differences in pull-out between any of the screw types. Correlation between insertional torque and pull-out strength was statistically significant only with the Texas Scottish Rite Hospital and Steffee VSP in L4 and AO Schanz in L5. CONCLUSIONS: A conical screw profile increases insertion torque, although insertional torque is not a reliable predictor of pull-out strength in cadaveric bone. Screw profile (with similar dimensions) has little effect on straight axial pull-out strengths in cadaveric bone.     

A retrospective six-months clinical trial of adhesive precoated brackets and bonding system

This study investigated bond failures in two groups of 75 patients. Either adhesive precoated (APC) or control brackets were bonded from bicuspid to bicuspid in the mandibular and maxillary arch by a single experienced operator. Observations on failure were recorded at initial arch wire insertion and for the first six months of treatment. The APC bracket failed significantly more often than the control at initial arch wire insertion in both maxillary and mandibular teeth. Further examination disclosed that the APC bracket, when bonded to mandibular teeth, also failed significantly more often than the control during the subsequent six months of treatment. At the six-month point of the study, a total of 53 bond failures had occurred at 671 bond sites in the APC group (7.89 per cent failure rate), compared to 27 bond failures at 977 bond sites in the control group (2.76 per cent failure rate). Fourteen patients in the APC group and two patients in the control group experienced bond failure at initial arch wire insertion. Twenty-eight patients in the APC group and 13 in the control group experienced bond failures within the first six months following initial arch wire insertion.     

Impact of chronic cough on quality of life

STUDY DESIGN: The biomechanical influence of in situ setting hydroxyapatite cement was examined for use in pedicle screw revision surgery. Pull-out testing of control and pedicle screws augmented with hydroxyapatite cement was performed in human cadaver vertebrae. OBJECTIVES: To determine the immediate effect of using hydroxyapatite cement to augment revision pedicle screws after failure of the primary pedicle screw fixation. SUMMARY OF BACKGROUND DATA: The potential problems associated with using polymethylmethacrylate to augment revision pedicular instrumentation have prompted the search for other solutions. The introduction of resorbable hydroxyapatite pastes may have provided new biocompatible solutions for pedicle screw revision. METHODS: Ten human cadaver vertebrae were instrumented with 6.0-mm pedicle screws in each pedicle. The screws were loaded to failure in axial tension (pull-out). The failed pedicles then were instrumented with 7.0-mm pedicle screws, either augmented with hydroxyapatite cement or nonaugmented, which also were loaded to failure. Finally, the nonaugmented 7.0-mm screw hole was reinstrumented with a hydroxyapatite cement-augmented, 7.0-mm pedicle screw and loaded to failure. RESULTS: The pull-out strength of the 7.0-mm, hydroxyapatite cement-augmented screws was 325% (P = 2.9 x 10(-5)) of that of the 6.0-mm control screws, whereas the strength of the 7.0-mm nonaugmented screws was only 73% (P = 2.0 x 10(-2)) of that of the 6.0-mm control screws. The 7.0-mm screws augmented with hydroxyapatite cement also were able to salvage 7.0-mm pull-out sites to 384% (P = 6.9E-5) of the pull-out strength of the 7.0-mm nonaugmented screws. CONCLUSIONS: Hydroxyapatite cement may be a mechanically viable alternative to polymethyl methacrylate for augmenting revision pedicular instrumentation and should be considered for future experimental, animal, and clinical testing.     

G105反扣钻杆胀扣失效分析

G105反扣直在油田使用过程中发生胀扣失效,为寻找胀扣失效的原因,首先分析了钻杆在服役过程中的载荷情况,然后通过计算机工况仿真得到了钻杆在不同载荷条件下的失效形式,说明钻杆胀和主要是由于工作扭矩超过了钻杆工具接头应有的实际抗扭屈服能力造成的。     

单压下节理密度及倾角对类岩石试件强度及变形的影响

通过预制张开节理类岩石试件,在单轴压缩条件下,研究节理密度及倾角的组合作用对试件强度和变形特征的影响.试验结果表明:(1)随着节理倾角的增大,应力-应变曲线由多峰值转变为单峰值,试件脆性增强,延性减弱;(2)节理密度对当量峰值强度的影响与节理倾角大小有关,对当量弹模的影响呈“V”形变化,即当量弹模随着节理密度的增大呈现先减小后增大的变化规律;(3)当量弹模随节理倾角的增大而增大,在节理倾角为90°的时候达到最大值,为完整试件弹性模量的70%~80%;(4)节理倾角对多节理类岩石试件当量峰值强度和当量弹性模量的影响大于节理密度的影响.对试验结果进一步分析发现:节理密度及节理倾角与应力-应变曲线、当量峰值强度及当量弹性模量之间的关系,其变化规律与试件的破坏过程息息相关,其破坏模式可分为张拉破坏、剪切破坏和复合破坏.      

Titanium screw implants for intermaxillary fixation of partially edentulous jaw

Establishment of the best possible relationship between upper and lower teeth is very important when treating jaw fractures and orthognathic deformities in partially edentulous patients. Many surgeons use arch bars and acrylic splints for intermaxillary fixation (IMF) to obtain the best occlusal relationships after the operation. In patients with sufficient teeth, IMF is not so difficult to realize. However, in partially edentulous patients, the available teeth may not be sufficient to apply arch bars or splints. This paper describes a system for IMF of a partially edentulous jaw. Screws made of medical-grade titanium are implanted into the alveolar ridges where two or more teeth are missing. Arch bars or acrylic splints secured on these implants and available teeth can be used safely for IMF. In vitro axial pull-out tests demonstrated that these implants can withstand the traction forces generated by elastics. Five partially edentulous patients, three with mandibular fractures and two with orthognathic problems, were treated with these implants. All patients healed without any complications and with the best possible occlusal relationships.     

The effect of growth and joint formation on bristle pattern in D. melanogaster

Dependence of bristle pattern on size and joint formation was studied for male first leg tarsi of fj (four jointed) and d (dachs) mutants in homozygotes and in mosaics resulting from X-ray induced mitotic recombination. Homozygotes have four tarsal segments, lacking a third tarsal joint in most cases. The two proximal segments are shortened, the first by one-third, and altered in bristle pattern, whereas the distal two segments are little affected. Expressivity of fj is high, and of d is low, for the extent and frequency of joint failure. The longer the second segment, the more complete the third joint and the greater the bristle number. Only the jointed side of the segment approximates two segments in its bristle pattern. Mosaic studies show that joint failure occurs autonomously in fj, or in the majority of d clones, and that joint formation by heterozygous clones is autonomous except in the border area contacting a fj or d spot lacking a joint, in which are a joint failure occurs. Bristle pattern in this jointless heterozygous area switches to that of a single segment. Localized non-autonomy also occurs in the t-rows of heterozygous tissue contacting a fj or d spot. Both mutant genes are interpreted as reducing longitudinal growth of the proximal tarsi, with joint failure as a consequence, and with alterations of bristle pattern resulting directly from size reduction, or indirectly through joint failure.     

Dentastic bond strength to dentin

PURPOSE: To evaluate the shear bond strength to the dentin of permanent teeth and failure site of Dentastic hydrophilic dentin bonding agent. MATERIALS AND METHODS: Forty permanent noncarious molar teeth stored in distilled water were obtained. The teeth were cleaned with pumice and a rubber cup. The mesio-buccal surface of the teeth was ground flat with hand pressure with a series of SiC paper ending with the 600 grit to provide a uniform surface on dentin to which the resin composite could be applied. After preparing the tooth surface, the teeth were stored in distilled water for 48 hours. They were then divided at random into four groups of 10 specimens each: Group 1: Dentastic, five coats of primer; Group 2: Dentastic, three coats of primer; Group 3: Dentastic, five coats of primer, light-cured adhesive before resin bonding; Group 4: Dentastic, three coats of primer, light-cured adhesive before resin bonding. All specimens were thermocycled (500x) and sheared in a testing machine. After shear testing, the debonded sites of all samples were examined with a stereomicroscope and a scanning electron microscope. RESULTS: The results in MPa were: Group 1: 22.63 +/- 6.24; Group 2: 23.35 +/- 5.14; Group 3: 23.58 +/- 5.66; Group 4: 27.26 +/- 8.22. ANOVA and Student-Newman-Keuls showed no statistically significant difference between the groups. In all groups, all specimens failed at the dentin (dentin cohesive failure = dentin fracture) or at the resin (resin cohesive failure = resin fracture). This means that the bond strength of the product is stronger than the cohesive strengths of the dentin and the resin.     

Bond strength and interfacial morphology of adhesives to primary teeth dentin

PURPOSES: To evaluate (1) the shear bond strength to the dentin of primary teeth and failure site of hydrophilic dentin bonding agents, (2) the interfacial micromorphology of these adhesives on primary teeth. MATERIALS AND METHODS: Seventy-six primary noncarious molars stored in distilled water were obtained. The teeth were cleaned with pumice and a rubber cup. The mesio-buccal surface of the teeth was ground flat with hand pressure with a series of SiC paper ending with the 600 grit to provide a uniform surface on superficial dentin to which the adhesives and resin composite could be applied. After preparing the dentin surface, the teeth were stored in distilled water for 48 hours. They were then rinsed and dried with compressed air and divided at random into four groups of 16 specimens each: Group 1: Dentastic; Group 2: One-Step; Group 3: Prime & Bond 2.0; Group 4: Compoglass SCA. Z100 resin was used in all groups. All specimens were thermocycled (500x) and sheared in an Instron machine. After shear testing, the debonding sites of all samples were examined with a stereomicroscope and selected samples were also examined with the scanning electron microscope. Three additional samples per group were used to evaluate the resin adaptation to dentin. RESULTS: The results in MPa were: Dentastic 19.62 (4.67); One-Step 11.24 (3.67), Prime & Bond 22.38 (6.47), Compoglass SCA 18.88 (4.04). ANOVA (P < 0.0001) revealed that there was a significant difference between the groups. The Student-Newman-Keuls test (P < 0.05) showed no statistically significant difference between Dentastic, Prime & Bond and Compoglass SCA. However, these three groups were statistically significantly higher than One Step. In the Dentastic group, 14 of 16 samples revealed resin cohesive failure (resin fracture) while two of 16 displayed dentin cohesive failure (dentin fracture). In the One Step group, 15 samples failed at the resin and one sample showed dentin cohesive failure. In the Prime & Bond group, 12 specimens revealed resin cohesive failure while four displayed dentin cohesive failure. In the Compoglass SCA group, 13 samples had resin cohesive failures while three had dentin cohesive failures. All samples revealed an intimate adaptation to the dentin displaying resin tag formation.     

鼓形齿式联轴器失效分析

鼓形齿式联轴器在韶钢二轧厂应用中出现联接螺丝断裂、孔壁变形及扫齿等导致联轴器失效．针对上述问题进行了力学分析及强度校核，找出了失效原因，并采取了相应解决措施．