复合材料多墙盒段弯扭耦合下的屈曲和后屈曲

针对复合材料典型多墙盒段，采用试验和有限元分析相结合的方法，研究了弯扭耦合载荷作用下的稳定性、承载能力及损伤起始、扩展情况．试验采用数字图像相关(Digital Image Correlation, DIC)测量方法捕捉试验件屈曲模态的变化过程，通过载荷-应变曲线获得屈曲和后屈曲破坏载荷．数值仿真基于ABAQUS/Explicit模块，采用Hashin准则结合刚度降的VUSDFLD子程序模拟复合材料的屈曲和后屈曲行为．研究结果表明，多墙盒段在弯扭载荷组合作用下发生屈曲时，扭矩会改变屈曲模态的分布形式和对称性，屈曲鼓包依然保持波峰、波谷交替出现；多墙盒段后屈曲阶段历程较长，屈曲模态由一阶向高阶逐渐发展，直到结构发生过大变形，彻底破坏而失去承载能力．

Buckling and Post Buckling of Composite Multi-Wall Box Section under Bending-Torsion Coupled Loads

In this paper, a research on the typical multi-wall box section of composite materials is carried out. The stability, load-bearing capacity, damage initiation and propagation under the bending-torsional coupled loads were studied by experimental tests and finite element analysis. Using (Digital Image Correlation, DIC) method, the change of buckling mode of the test piece was captured. The buckling and post-buckling strengths were determined from the load-strain curves. In the numerical simulations, the buckling and post buckling behaviors were investigated using the Hashin criterion combined the VUSDFLD subroutine incorporating the stiffness reduction based on the ABAQUS/Explicit module. The results show that when the multi-wall box section buckles under the bending-torsional coupled loads, the torque will change the distribution and symmetry of the buckling mode, with the peaks and troughs appearing alternately. The multi-wall box section has a long post-buckling stage, with the buckling mode gradually developed from first-order to high-order, until the structure is completely destroyed and loses its load-bearing capacity due to excessive deformation.