Results of a parametric investigation carried out on the local joint flexibility (LJF) of multi-planar tubular TT-joints, also called two-planar DT-joints, are presented and discussed in this paper. A set of finite element (FE) analyses were conducted on 81 FE models subjected to two types of axial loading in order to study the effects of geometrical properties of the DT-joint on the LJF factor (f_LJF). Developed FE models were validated using available experimental data and parametric equations. Results indicated that the increase of the γ leads to the increase of the f_LJF; while the increase of the β and/or the τ leads to the decrease of the f_LJF. In joints with bigger values of the γ, the increase of the β results in more drastic decrease of the f_LJF. The amount of the f_LJF change due to the increase of the parameter τ is much smaller compared to the other geometrical parameters. The f_LJF values in two-planar DT- and uniplanar T-joints were compared. Results showed that the multi-planarity effect on the LJF is considerable and consequently the application of the equations already available for uniplanar T-joints to calculate the f_LJF in two-planar DT-joints may result in highly over- or under-predicting results. To tackle this problem, FE results were used to derive a new parametric equation for the prediction of the f_LJF in axially loaded two-planar DT-joints and the developed formula was checked against the UK DoE acceptance criteria.

本文介绍并讨论了对多平面管状 TT 接头（也称为双平面 DT 接头）的局部接头柔度 (LJF) 进行的参数研究的结果。对 81 个承受两种轴向载荷的有限元模型进行了一组有限元 (FE) 分析，以研究 DT 接头的几何特性对 LJF 因子 ( f _LJF ) 的影响。使用可用的实验数据和参数方程验证开发的有限元模型。结果表明，γ的增加导致f _LJF的增加；而β和/或τ的增加导致f _LJF的减小. 在具有较大γ值的接头中，β的增加导致f _{LJF 的}更急剧下降。与其他几何参数相比，由于参数τ的增加而导致的f _LJF变化量要小得多。_比较了双平面 DT 和单平面 T 型接头中的f _LJF值。结果表明，多平面性对 LJF 的影响是相当大的，因此应用已经可用于单平面 T 型接头的方程来计算f _LJF在双平面 DT 接头中可能会导致高度高估或低估的结果。为了解决这个问题，有限元结果被用来推导出一个新的参数方程，用于预测轴向加载的双平面 DT 接头中的f _LJF，并根据英国能源部的验收标准检查开发的公式。