油管的疲劳强度分析  

Fatigue Strength Analysis of Oil Tube

作　　者：崔旭明[1] 何富君[1] 张晶[2] 罗敏[1] 

机构地区：[1]大庆石油学院机械科学与工程学院,黑龙江163318 [2]大庆油田有限责任公司第十采油厂,黑龙江163315

出　　处：《实验力学》2004年第1期72-78,共7页Journal of Experimental Mechanics

摘　　要：疲劳断裂是油管失效的形式之一,本文针对抽油机井常用油管(J55,2 ")在循环载荷作用下的断裂问题进行了理论与实验研究。实测了井口处油管载荷谱与应变谱,得到了油管载荷的变化规律,同时通过在室内建立模拟油管工况的试验台,得到了油管从上扣到加载的全过程中油管螺纹段内壁的环向、轴向、剪应变等的变化规律。并且采用油管螺纹段轴对称接触模型进行了弹塑性有限元分析,计算了油管螺纹内的应力应变场,发现油管内第一啮合齿齿根处应力应变最大,应力已经进入屈服阶段,油管是在高应力应变水平和低应力应变幅状态下工作。并利用局部应力应变法进行了相应的疲劳实验,得到油管的疲劳断裂条件,当油管内的应力应变进入强化段εeq>10-2ε,塑性应变幅超过4×10-5ε时,油管就会发生疲劳断裂。Fatigue fracture is one kind of failure for oil well tubes of oil sucking machines. In this paper, the fracture of oil tubes (J55, 21/2 in) under cyclic loading are investigated theoretically and experimentally. The actual loads on tubes were obtained by measuring the load strain spectra on well portal, which were subsequently used to simulate the working conditions of the oil tubes on a purpose-built test platform. Variation of axial strain, hoop strain and shear strain on the inner wall of tube thread were acquired during the process of thread making up and loading. The elasto-plastic finite element method was used to calculate the internal strain and stress fields of oil tube thread on the basis of the measured load and strain spectra on site, then the fatigue experiments were conducted according to the local stress-strain method to obtain the fatigue resistance. It is found that the root of the first engaged thread on oil tube bears the maximum strain and stress, which has reached its yield limit. It is also found that when the tube material is stressed into its strengthening region (i.e. the equivalent strain is more than (0.01)), and the plastic strain amplitude is greater than 4×10^(-5)ε, the fatigue fracture will occur.

关 键 词：油管 疲劳强度 疲劳断裂 有限元 实验力学 石油工业 

分 类 号：TE832.1[石油与天然气工程—油气储运工程] O346.2[理学—固体力学]