缩径焊接空心球压弯下节点刚度研究

以缩径焊接空心球节点为研究对象,运用正交设计法设计了9个试件,试验研究了压弯受力状态下节点的名义抗弯刚度。利用ABAQUS软件建立缩径焊接空心球节点分析模型,采用线性强化应力-应变关系,考虑几何和材料非线性的影响,对压弯受力状态下的缩径焊接空心球节点的抗弯刚度进行了有限元分析,绘制了节点弯矩-转角曲线,得到了节点名义抗弯刚度,验证了有限元模拟的准确性。进而参数化分析了不同因素对节点抗弯刚度的影响。以虚功原理为基础,推导了压弯作用下缩径焊接空心球节点抗弯刚度简化计算公式。结果表明:在本文研究范围内,节点的破坏模式为球凹陷破坏;锥管小径端直径与球径比d/D对节点抗弯刚度的影响最大,球壁厚与球径比t/D的影响次之,锥管长度L的影响最小;本文提出的缩径焊接空心球节点刚度简化计算公式具有一定的精度。

Study on bending stiffness of welded hollow spherical joints with reduced pipe-diameter based on compression-bending states

The welded hollow spherical joints considering reduced pipe-diameter are taken as the research object. 9 kinds of joints were designed by orthogonal design and used in compression-bending loading tests. The nominal bending stiffness in compression-bending loading states was studied by experiments. The finite element model of joints considering reduced pipe-diameter is established and analyzed by ABAQUS software with the consideration of nonlinearity. Linear hardening stress-strain relationship is adopted. The influences of geometric and material nonlinearities are considered. The bending stiffness of reduced pipe-diameter welded hollow spherical joints subjected to compression-bending loads is analyzed by finite element method. The moment-rotation curve of joints is obtained and the nominal bending stiffness is calculated. Then the influence of different factors on bending stiffness of joints is analyzed and the accuracy of finite element simulation is confirmed. Based on the principle of virtual work, the formula for bending stiffness of the joints under compression-bending loading states is derived. The analysis shows that: within the scope of this study, the failure mode of joints is spherical concave failure;ratio of the diameter of the reduced pipe-diameter canal to the diameter of hollow sphere d/D has the greatest influence on flexural stiffness of joints;ratio of the thickness of hollow sphere to the diameter of hollow sphere t/D has the second effect;the length of the reduced-diameter canal L has the least impact. The simplified formula for bending stiffness of reduced pipe-diameter welded hollow spherical joints presented in this paper is of certain accuracy.