Bonded composite scarf joints with bonding flaws were tested to study their tensile behaviors. Based on the failure modes obtained by various observation methods, an improved numerical methodology with appropriate model width was developed, considering the marginal low stiffness regions in ± 45° plies. The results show that the modelling approach provides accurate predictions on the strength, stiffness, and the failure modes considering variations in scarf angle, flaw size, and flaw location. Marginal low stiffness regions in ± 45° plies influence the stress distributions in the adhesive layer and the failure mode. Adhesive layer failure is the main cause of the final fracture of the pristine and the defective scarf joints, and damages within composite adherend especially interlaminar delamination, may accelerate the growth of the bondline stress at an early stage. The traditional damage tolerance design approach for bonded composite joints needs to be improved to avoid confusing and adventurous results.

测试了具有粘合缺陷的粘合复合围巾接头以研究它们的拉伸行为。基于通过各种观察方法获得的失效模式，考虑到 ± 45° 层的边缘低刚度区域，开发了一种具有适当模型宽度的改进数值方法。结果表明，考虑到斜角、缺陷尺寸和缺陷位置的变化，建模方法可以准确预测强度、刚度和失效模式。± 45° 层中的边际低刚度区域影响粘合剂层中的应力分布和失效模式。胶层失效是导致原始的最终断裂和有缺陷的围巾接头，以及复合被粘物内部损坏特别是层间分层的主要原因，可能会在早期加速粘合层应力的增长。粘合复合材料接头的传统损伤容限设计方法需要改进，以避免混淆和冒险的结果。