复合材料多墙盒段后屈曲的破坏预测方法

PREDICTION AND DAMAGE ANALYSIS OF THE POSTBUCKLING FOR MULTI-SPAR COMPOSITE BOX

目前复合材料垂尾已广泛运用在多种飞机型号上,为了保证结构安全,研究复合材料垂尾盒段的力学特性十分必要。建立在弯剪载荷下垂尾盒段屈曲和后屈曲的模型,重点研究了在弯剪载荷下后屈曲诱发的盒段蒙皮铺层间、蒙皮/缘条之间界面的失效问题;其中蒙皮铺层之间采用实体单元进行连接,连接界面采用二次应力准则作为损伤的起始判据,能量混合准则作为损伤的扩展判据,并且自定义损伤变量实现刚度的非线性衰减;蒙皮与缘条之间采用cohesive单元模拟胶层;复合材料壁板采用断裂面准则作为失效判据,该判据能有效判断基体的失效。该模型基于Abaqus动态显式分析步,屈曲模态、屈曲载荷、破坏形式与极限载荷与实验吻合良好,证明了该方法的有效性。

as multi-spar composite box has been used for many airplanes,in order to assure structure security,it is necessary to study the mechanical properties of multi-spar composite box. Aiming at the buckling and postbuckling problems,buckling behavior and damage process of multi-spar composite box under bending-shearing load is researched in this paper. A self-defined nonlinear degradation rule was presented to simulate the propagation of the interface elements which were discretized with solid elements. In this model,the onset and propagation of damage can be predicted by quadratic failure criteria and mixed-mode strain energy release rate criteria respectively. cohesive elements are used to simulate the adhesive layer between skin and flange.composite structures were discretized with continuum shell elements. In this paper,a failure algorithm based upon Puck＇s failure theory has been developed. Based on ABAQUS,a material degradation rule of composite was presented. The process of damage initiation,propagation and failure of the stiffened composite panels was simulated in detail. At last,a good agreement between tests and numerical prediction was observed.