Multi-cell, multi-corner and adding edge-junctions structures are widely used approaches to enhance the crash characteristic of the thin-walled structures. In this study, the crashworthiness of twenty-one structures combining these three structures is examined under axial and oblique loading angles. The finite element models under axial loading are validated by experimental data from the literature and theoretical approach. In the theoretical approach, removing the corner elements in the inner structure from the theoretical calculation in multi-cell tubes has increased the accuracy. With the validations performed in axial loadings, it is predicted that the finite element model will be accurate also in oblique loadings. On the other hand, rupture strain has not been used in finite element models, which may cause some errors. Crashworthiness performance has improved as the cell number increases under all loading conditions except the C2 tube under 20-degree oblique loading. Also, the sub-sections added to the inner wall corners of the tubes significantly increase the energy absorption capacity. The complex proportion assessment (COPRAS) method and the technique for order of preference by similarity to ideal solution (TOPSIS) are utilized to get the tube with the best crashworthiness performance. The entropy method is used for weighting to avoid human intervention. The best tube varies depending on the weighting and selection method. Finally, the radial basis function (RBF) approximation approach and four multiobjective optimization methods are used to obtain optimum sizes of the C4O tube. The results of the optimizations show that the optimum structure does not differ depending on the optimization method, and the results are very close to each other.

多单元，多角和增加边缘连接的结构被广泛使用来增强薄壁结构的碰撞特性。在这项研究中，在轴向和倾斜载荷角下研究了结合这三种结构的二十一种结构的耐撞性。通过文献和理论方法的实验数据验证了轴向载荷下的有限元模型。在理论方法中，从多单元管的理论计算中删除内部结构中的角部元素已提高了精度。通过轴向载荷的验证，可以预测有限元模型在倾斜载荷下也将是准确的。另一方面，在有限元模型中没有使用断裂应变，这可能会引起一些误差。除了在20度倾斜载荷下的C2管以外，在所有载荷条件下，单元数都增加了，耐撞性性能得到了改善。而且，添加到管内壁角的子部分显着提高了能量吸收能力。利用复杂比例评估（COPRAS）方法和通过类似于理想解决方案的优先顺序排序技术（TOPSIS），以使管具有最佳的耐撞性能。熵方法用于加权以避免人为干预。最好的试管根据权重和选择方法的不同而不同。最后，使用径向基函数（RBF）逼近方法和四种多目标优化方法来获得C4O管的最佳尺寸。