© 2019 International Committee on Composite Materials. All rights reserved. Numerical analyses were conducted to investigate the detailed fracture behavior in the mode II fracture toughness test. Three models, including cohesive zone modeling (CZM) were used to evaluate the failure of an adhesive and an adherend, separately. The results showed that CZM can be used to accurately simulate crack extensions along the adhesive layer. The model with solid elements and zero-thickness cohesive elements can be used to effectively evaluate the failure of adherends, based on their shear stress distribution.