通过试验和三维有限元分析研究了换热器中管子与管板连接的液压胀接、焊接以及胀焊结合接头(包括先焊后胀以及先胀后焊两种情况)的拉脱力大小和失效形式。有限元分析考虑了接头的几何非线性、材料非线性、接触非线性以及热固耦合，从而能模拟接头材料的弹塑性变形、热塑性以及先胀后焊过程中焊接热对胀接的影响。研究结果表明，焊接接头的拉脱力远大于液压胀接接头的拉脱力，并且略大于胀焊结合接头的拉脱力；对于先胀后焊或者先焊后胀接头，拉脱力并没有明显的变化；在拉力作用下，胀接接头的破坏主要是管子与管板接触面间的拉脱破坏，而焊接接头的破坏主要为焊缝的剪切破坏。

The pullout forces and failure forms of hydraulically expanded, welded, and expanded-and-welded (including expanding prior to welding and welding prior to expansion) tube-to-tubesheet joints in heat exchangers have been experimentally and numerically studied. Geometrical, material and contact nonlinearities, as well as coupling of heat and structure in the finite element analysis were considered in order to simulate the elasto-plastic and thermoplastic behaviors of the joint materials and the influence of the welding heat on the expanded connections. The results show that the pull-out force of the welded joint is much larger than that of the hydraulically expanded joint and even slightly larger than that of the expanded-and-welded joint. There is no significant difference between the pull-out forces of the joint expanded prior to welding and that welded prior to expansion. Under tensile loadings, the failure of the expanded joint was found to involve the pull-off damage of the tube and tubesheet connection, while the failure of the welded joint involved mainly a shear break of the welding.