含缺陷复合材料加筋壁板承载能力的数值预测

碳纤维复合材料加筋壁板是飞机结构的典型部件,成型过程中的制造缺陷对其极限承载能力和失效行为具有显著影响,是结构完整性评估的重要内容。通过数值手段开展了3点弯曲载荷作用下含缺陷复合材料加筋壁板的数值分析,重点考虑了缺陷尺寸和位置对结构承载能力的影响。首先基于Abaqus/Standard建立了加筋壁板的三维有限元模型,引入双线性内聚力模型用于描述复合材料加筋壁板的层间失效行为,然后结合文献相关实验数据验证了该模型的有效性,最后基于该有限元模型研究了缺陷尺寸和位置对结构承载能力的影响。结果表明:建立的有限元模型计算结果与文献实验结果吻合;结构的承载能力随着缺陷尺寸的增大而降低,且对蒙皮/桁条界面中部缺陷较为敏感;缺陷的存在导致结构的破坏模式发生转变,但起始裂纹始终发生在界面附近的基体区域。

NUMERICAL SIMULATION OF CARRYING CAPACITY OF COMPOSITE REINFORCED PANELS WITH DEFECT

Carbon fiber composite Skin/Stringer is a typical component of aircraft structure.However,the manufacturing process of laminated composite structure can lead to the existence of defects in the bonds.The pre-existing defects have a great effect on the ultimate bearing capacity and failure behavior of Skin/Stringer.Therefore,it is important to assess structural integrity.In this paper,the specimens were subjected to three-point bending.To evaluate the debonding mechanisms between the skin and the stringer,different sizes and locations of defects were taken into consideration.First,a three-dimensional finite element model based on Abaqus/Standard was established,and the bilinear cohesive zone model (CZM) was used to simulate the interface failure between the skin and the stringer;Then,the validity of the model were verified through the experimental data of the literatures.Finally based on the finite element model,the influence of the sizes and locations of the defects on the failure modes and the load-carrying capacity of the structure were investigated.The result indicats that the calculated results show good agreement with those of experiments.The load capacity of the structure is found to decrease with increasing defect size,and SkinStringer is very sensitive to defects at the middle of the interface;The failure modes of the Skin/Stringer changes because of the pre-existing defects.But the initial crack always occurs in the matrix near the interface area.