【作者】 罗会亮；

【导师】 柳葆生；

【作者基本信息】 西南交通大学 ， 工程力学， 2012， 硕士

【摘要】 井架由于使用环境恶劣,结构常会出现局部缺陷,如锈蚀、穿孔、切口、斜撑松动或缺失、销接间隙等。在使用的过程中还会出现载荷偏心和基础下沉等载荷和位移边界条件缺陷。这些缺陷会对井架的承载性能产生影响。本文针对实验室特制K型模型井架,采用有限元方法,通过与理想模型模拟结果对比,分析了缺陷对井架结构受力和结构稳定性的影响。分析结果显示,井架大腿局部锈蚀、穿孔、切口、斜撑缺失仅对结构局部受力有影响,对其余杆件受力影响不大；基础下沉、井架载荷偏心和销接间隙对整体结构的受力影响较大。井架载荷偏心、基础下沉、斜杆缺失对井架稳定性影响较大,销接间隙的影响较小。起升是井架使用过程中比较危险的环节,本文分析了JJ225/42-K井架的起升工况。分析结果显示,0°是井架起升过程中的最危险角度,此时的起升力最大、结构受力最恶劣。随着起升角度的增大,起升力减小,结构所受最大应力变小。起升过程中,井架前腿的中下段受力较大。本文工作中,按照井架测试规范,对实验室特制K型模型井架进行5级载荷静力测试。测试结果表明,模型井架四根大腿受力严重不均。对井架进行了安全承载能力实验评估。本文通过缺陷对结构的影响分析,将载荷偏心、基础下沉和销接间隙作为导致实验室模型井架大腿受力不均的主要原因。在已知载荷偏心量和基础下沉量的前提下,以销接接触刚度作为参数对有限元模型进行局部模型修正。与5级载荷下的静载应力测试结果进行对比验证。结果表明,模拟和测试结果相对误差小于17.48%,证明了销接接触刚度法的可行性。在本文中,修正后的模型被用于对模型井架进行安全性能评估。更多还原

【Abstract】 Due to the severe service condition, some local defects appear often in the derrick structures, such as corrosion, perforation, incision, diagonal bracing loosing or missing, pin joint gap and so on. The unusual loading and boundary conditions may happen during the process of using derrick, too, such as the load eccentricity and foundation sinks of the derricks. The load-carrying capacity of the derricks is affected by these defects described above.In the present paper, the affection of defects on the K style laboratorial derrick is analyzed by FEA method. By comparation with the simulation results of a model without defect, the effects of above mentioned defects on stress distribution and structural stability of the derrick are analysized. The corrosion, perforation, incision on the leg of derrick and diagonal bracing missing represent only the local effects on stress distribution of the structure. The foundation sink, load eccentricity and pin joint gap have the important global influence on the structural stress distribution. The diagonal bracing missing, foundation sinks and load eccentricity prohibit the significant impacts on stability of the derrick, while the defect of pin joint gaps doesn’t affect a lot.The process of lifting derrick is a dangerous procedure for the service of derrick. In this paper, the lifting process of JJ225/41-K is simulated by ANSYS. When the lifting angle is zero, the lifting force takes it maximum value, and structure supports the most severe loads. With the increase of lifting angle, the load subjected by structure and the stress in the structure decreases. When the derrick is lifting up, the loads in fore legs of the derrick are greater than in the other parts.In this paper, the static stress test of laboratorial derrick under the five increasing load steps is carried out according the derrick test specification. The test result shows that the stresses in four legs of derrick are severely uneven. The evaluation on derrick safety and carrying capacity is done based on the experimental data.By virtue of the analysis on effect of the defects in the structure, the load eccentricity, foundation sink and pin joint gap are considered to be the main causes of the uneven loads in the legs of laboratorial derrick. Under the condition of known values for load eccentricity and fundation sink, the stiffness of gaped pin joint is used as the parameter to correct locally the FEA model. By comparison with the measurement results of the test under five increasing load steps, the errors of simulation results relative to the test ones are smaller than17.48%. It shows that the stiffness model for gaped pin joint is well feasible. The corrected FEA model is then used to evaluate the safety performance.更多还原