共查询到20条相似文献,搜索用时 78 毫秒
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结合钻杆服役工况,通过失效试样宏观形貌分析、磁粉检测分析、理化性能分析,对钻井过程中φ127×9.65 mm钻杆外螺纹接头及焊区部位缩颈失效的原因行了分析。结果表明:钻井过程中岩屑在外螺纹接头35°台肩面附近堆积,随着堆积的岩屑增多,直接堵塞钻井液循环通道。钻井过程中在拉伸和扭转的复合加载下,钻杆外螺纹接头及焊区部位与岩屑之间发生剧烈摩擦,生成的大量摩擦热使得接头及焊区部位温度迅速升高,处于高温部位的材质发生塑性拉长形变,接头外径、内径迅速减小,从而导致钻杆接头及焊区部位出现缩颈失效。 相似文献
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对开裂的天然气集气末站汇管进行了宏观形貌、显微组织、化学成分分析和力学性能测试、断口形貌观察以及腐蚀产物相组成确定,对其开裂原因进行了分析。结果表明:集气末站汇管开裂裂纹位于汇管的焊缝区,裂纹分为表面裂纹与隐藏裂纹,裂纹性质属氢致开裂和应力导向氢致开裂;设备内壁防腐涂层质量低劣是导致开裂的主要原因,焊接工艺不当对开裂有明显的促进作用。 相似文献
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The reliability of electronic assemblies is largely affected by the health of interconnects, such as solder joints, which provide mechanical, electrical and thermal connections between circuit components. During field lifecycle conditions, interconnects are often subjected to a DC open circuit, one of the most common interconnect failure modes, due to cracking. An interconnect damaged by cracking is sometimes extremely hard to detect when it is a part of a daisy-chain structure, neighboring with other healthy interconnects that have not yet cracked. This cracked interconnect may seem to provide a good electrical contact due to the compressive load applied by the neighboring healthy interconnects, but it can cause the occasional loss of electrical continuity under operational and environmental loading conditions in field applications. Thus, cracked interconnects can lead to the intermittent failure of electronic assemblies and eventually to permanent failure of the product or the system. This paper introduces a model-based prognostic approach to quantitatively detect and predict interconnect failure using impedance analysis and particle filtering. Impedance analysis was previously reported as a sensitive means of detecting incipient changes at the surface of interconnects, such as cracking, based on the continuous monitoring of RF impedance. To predict the time to failure, particle filtering was used as a prognostic approach using the Paris model to address the fatigue crack growth. To validate this approach, mechanical fatigue tests were conducted with continuous monitoring of RF impedance while degrading the solder joints under test due to fatigue cracking. The test results showed the RF impedance consistently increased as the solder joints were degraded due to the growth of cracks, and particle filtering predicted the time to failure of the interconnects similarly to their actual timesto- failure based on the early sensitivity of RF impedance. 相似文献
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随着小井眼开窗侧钻技术的广泛应用,由井下弯曲段引起的钻具接头失效问题日益突出。为解决因弯曲载荷造成钻具接头变形失效的问题,根据弹塑性力学理论及中心管材料本构模型试验研究结果,建立了钻具接头螺纹连接的三维有限元模型,研究了弯曲载荷作用下钻具接头连接强度和密封性能,并通过胀扣试验验证了有限元分析结果的可靠性。在此基础上利用正交优化方法,对其关键结构参数进行优化,获得了钻具接头较优参数组合,对比计算了API钻具接头与高抗弯钻具接头力学性能。结果表明,优化后的连接螺纹在抗拉/压、扭矩及弯曲方面性能均优于API螺纹,能更好地满足小井眼开窗侧钻的钻井要求。 相似文献
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运用三维建模软件Pro/E和有限元分析软件ANSYS,建立了虚拟样机模型。考虑结合面的影响,对机床进行了动态分析,研究结合面对于机械结构动态特性的影响,实现无物理样机环境下机床整体动力学性能预测和综合评价的目的。 相似文献
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Mustafa Kemal Kulekci Aydin Şik Erdinç Kaluç 《The International Journal of Advanced Manufacturing Technology》2008,36(9-10):877-882
The objective of this study was to determine the effects of the tool pin diameter and tool rotation on the fatigue behaviour of friction stir welded (FSW) lap joints. FSW lap joints of AA 5754 aluminium alloy plates were produced by means of a conventional semiautomatic milling machine. Consequently, defect free FSW lap joints were produced on alloy plates at a constant traverse speed but with different tool pin diameter and tool rotation. Therefore, within this study, tool rotation and the tool pin diameter were accepted as variable parameters, while others held fixed. The results of the tests performed, indicate that an optimisation is required for the studied parameters, in order to obtain reasonable fatigue strength. An index, related to tool rotation, traverse speed, pin diameter, and pin height can be identified and used to select optimum parameters for FSW applications. 相似文献
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Wen Zheng Ding Xiao Diao Huang Mu Lan Wang Song Qing Zhu 《The International Journal of Advanced Manufacturing Technology》2013,68(9-12):2025-2032
In order to select the best possible design from various candidates based on structure configurations of traveling components, it is essential to evaluate the effects of traveling joints on dynamic behavior of large machine tools. Firstly, regression analysis and energy method were used to determine the nonlinear parameters of the metal–plastic joints. Then, a nonlinear receptance coupling approach was used to establish a simplified model of a large machine tool including nonlinear joints. The evaluations of the large machine tool were analyzed with different milling forces. The results show that the nonlinearity of traveling joints significantly influences the resonant frequency and the response amplitudes. Experimental verifications were performed on a prototype of a large machine tool for milling large gears. 相似文献
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Mi Liang Yin Guo-fu Sun Ming-nan Wang Xiao-hu 《Journal of Mechanical Science and Technology》2012,26(2):495-508
The machine tool joint is a very important factor in the overall machine tool dynamic analysis, and it has great effects on
the machining performance of a machine tool. As a very important operation parameter, preload greatly influences the stiffness
and the damping of a machine tool joint. This paper presents the effect of preload on the dynamic stiffness of the spindle
nose of a horizontal machining center. By discussing types and distribution of machine tool joints, studies on the joints
of ball screws, linear guides and bolts are carried out. The influence of preload on the axial stiffness of a ball screw is
calculated based on Hertzian contact theory and the effect of pretightening moment on pressure of bolt joint is discussed,
while the dynamic stiffness and the damping of a linear guide are identified by an optimum algorithm with the simulated and
experimental results. A finite element model (FEM) of the whole machine tool structure considering the effects of different
joints is created and verified against the test results, and then the influence of preloads on ball screws and linear guides
is predicted. Results indicate that preloads on machine tool joints have significant effects on the dynamic stiffness of the
spindle nose. 相似文献
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J. Q. Li H. J. Liu 《The International Journal of Advanced Manufacturing Technology》2013,66(5-8):623-634
The nonrotational shoulder assisted friction stir welding (NRSA-FSW) is still in the feasibility study stage. To reveal details in the tool system designing and highlight advantages of this novel technology, the tool system for the NRSA-FSW was designed and utilized to weld high-strength aluminum alloy 2219-T6 for validations. Compared with the joints welded by the friction stir welding (FSW) without assistance of the nonrotational shoulder (NRS), the effect of the NRS on the weld formation and mechanical properties was illustrated. At a constant welding speed 100 mm/min, defect-free joints can only be obtained at the tool rotation speed 800 rpm by the FSW without assistance of the NRS, but the NRSA-FSW can produce defect-free joints in a wider range of tool rotation speeds 600–900 rpm. The NRS prevented all plasticized materials from escaping from the stirring zone, thus the weld nugget zone transformed from the basin-type formation to the spherical formation with increasing of the stirring effect when the tool rotation speed increased gradually. For joints welded by these two FSW processes, both the tensile strength and the elongation showed nearly the same trend with the tool rotation speed, but the NRSA-FSW can produce joints with the maximum tensile strength in a wider range. Compared with the maximum joint efficiency 71.2 % of the FSW without assistance of the NRS, the maximum tensile strength obtained by the NRSA-FSW also reached 69.0 % of the base material. All tensile specimens machined from defect-free joints fractured at the weakest region with minimum Vicker’s hardness; while for those joints with cavity defects, the fracture occurred at the defect location. 相似文献
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Nonlinear vibrational response of a single edge cracked beam 总被引:1,自引:0,他引:1
The nonlinear vibrational response of a breathing cracked beam was investigated. The study was done by using a new crack stiffness model to examine some of the nonlinear behaviors of a cantilever beam with a breathing crack. The quadratic polynomial stiffness equation of the cracked beam was derived based on the hypothesis that the breathing process of a crack depends on the vibration magnitude. The Galerkin method combined with the stiffness equation was used to simplify the cracked beam into a Single-degree-of-freedom (SDOF) lumped system with nonlinear terms. The multi scale method was adopted to analyze the nonlinear amplitude frequency response of the beam. The applicability of the stiffness model was discussed and parameter sensitivity studies on the dynamic response were carried out by the SDOF model for a cantilever beam. Results indicate that the new stiffness model provides an efficient tool to study the vibrational nonlinearities introuduced by the breathing crack. Therefore, it might be used to develop a nonlinear identification method of a crack in a beam. 相似文献
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整机是由许多通过结合部连接的构件组成的整体,而螺栓结合部是机床设计中的主要问题之一。螺栓结合部的结合状态比较复杂,研究过程和方法也相对复杂。结合面的研究首先从结合面的静态特性开始。该文首先简要介绍了影响结合部静态特性的主要因素及接触理论,并通过非线性接触表面层理论对螺栓结合部的接触变形进行了解析计算,为整机结合部的静态特性分析提供了边界条件。 相似文献