复合材料加筋壁板长桁凸缘变厚度设计对长桁-蒙皮界面承载能力的影响

长桁与蒙皮之间的脱胶是复合材料加筋壁板主要的失效形式之一。本文首先对复合材料机翼结构长桁-蒙皮典型结构进行了三点弯曲试验，获得破坏载荷以及界面失效模式。然后基于ABAQUS建立三维有限元模型，采用内聚力模型模拟界面的破坏情况。有限元计算结果与试验结果吻合较好，验证了有限元模型的合理性。在此基础上，对长桁凸缘宽度方向采用渐变厚度设计，开展了其对长桁-蒙皮界面承载能力的影响分析。研究结果表明采用变厚度设计可以减缓长桁凸缘末端附近的刚度突变，降低长桁凸缘末端与蒙皮之间界面的面外载荷。凸缘变厚度设计可以有效避免长桁与蒙皮界面过早出现脱胶失效，长桁凸缘末端越薄，界面脱粘载荷越大。

Influence of Variable Thickness Design for Stringer Flange on the Stringer-skin Interface Bearing Capacity of Stiffened Composite Panels

Stringer-skin debonding was one of the most important failure models in stiffened composite panels. In this paper, three-points bending tests were performed on representative stringer-skin structure of composite wing to simulate the flange-skin interface behavior and to obtain the failure mode and failure load. A 3D finite element model was built by using ABAQUS software to simulate interface failure with cohesive zone model. The numerical results agree well with test data, which validate the rationality of the finite element model. Influence of variable flange thickness design on stringer-skin interface bearing capacity was studied further. Results show that sudden stiffness change and out-of-plane load between stringer flange and skin at stringer flange edge was reduced by variable thickness design. Early flange-skin debonding failure was restrained significantly by variable flange thickness design. Thinner thickness at stringer flange edge results in higher interface debonding failure load.