钻杆开孔后剩余强度研究

为了对开孔后的钻杆进行剩余强度分析,运用有限元分析法对开孔后钻杆承受内压作用时的强度进行计算。建模时以API内加厚钻杆为研究对象,约束钻杆两边的轴向位移为0。在ABAQUS有限元分析软件环境下建立分析数据库,导入钻杆开孔后的三维实体模型,建立了有限元模型分析数据库。分析结果表明,钻杆开孔后,在内管壁施加的均布压力作用下,最大应力发生在开孔边缘的轴向位置附近,且随着开孔直径的增大,最大Mises应力也增大;在钻杆厚度一定的情况下,随着开孔直径的减小,应力集中因数逐渐减小,且趋近于恒定值;在相同的开孔直径下,钻杆直径越大,应力集中因数越大。

Research on the Residual Strength of Drillpipe After Tapping

To make a residual strength analysis of drillpipe after tapping,the finite element analysis method was used to calculate the strength of drillpipe which bears the effect of internal pressure.The API internal upset drillpipe was taken as the object of study in modeling,taking zero axial displacement on both sides of drillpipe as the constraining condition.Introducing the three-dimensional solid model of the tapped drillpipe,the finite element model analysis database was established in the environment of the ABAQUS software.The analysis shows that after drillpipe tapping the maximum stress takes place near the axial position on the edge of tapping due to the effect of the even distribution of pressure produced by inner tube wall.Moreover,the maximum Mises stress increases with tapping diameter.When the drillpipe thickness is certain,the stress concentration factor gradually decreases as the tapping diameter decreases.The factor tends to be a steady state value.When the tapping diameter remains the same,the larger the drillpipe diameter,the greater the stress concentration factor.