Abstract: The elasticplastic theories have been used to analyze the stresses and deformations ofcasing pipe under external pressure in this paper.The formulas obtained from this analysisare applicable for thin wall,medium thick wall and thick wall casing pipes. The elastic critical pressure,the elastic collapsing of the circular and elliptical casing pipes may be calculated.Examples from this analysis show that these calculated pressures are coincident with experimental results particularly, the supposition that the compression yield stress is 1.1 times the tensile yield stress used in reference papers[1.7] has been revised in this paper, Thisanalysis provides a basis for analyze stresses of casing wellpipe supported by multi-loads.

Key words: casing pipe, elastic theory, theory of plasticity, stability

摘要： 采用弹塑性理论分析套管在外压作用下的应力和变形,所得公式适用于薄壁、中厚和厚壁套管,可以计算套管(圆管和椭圆管)的弹性极限外压、弹性失稳外压和弹塑性失稳外压.算例表明理论分析的结果与实验值吻合.特别是修正了文献1～7中所采用的压缩极限应力是拉伸极限应力1.1倍的假设.该理论分析为在复杂受载下套管的应力研究提供了基础.

关键词: 套管, 弹性理论, 塑性理论, 稳定