Numerical analysis of effects of adhesive type and geometry on mixed-mode failure of adhesive joint
In the present study, the effects of the adhesive type and geometry (adhesive thickness and scarf angle) on mixed-mode failure of double scarf adhesive joint (DSJ) under uniaxial tensile loading were numerically examined using the finite element subroutine which coupled with a mixed-mode cohesive zone model (CZM). Especially, the effects of the adhesive type, which actually represent the influences of the cohesive parameters in mode I and mode II, on the mechanical properties of DSJ were discussed systematically. The numerical results reveal that the ultimate tensile loading and the necessary energy for failure of DSJ are controlled by the intrinsic components in mode I and mode II with different rates. Accordingly, the mathematical expressions for the ultimate tensile loading and the failure energy of DSJ with respect to the thickness-dependency cohesive parameters in two modes (I and II) and the scarf angle were deduced to identify each contribution in each mode component for a given type of adhesive. In addition, the numerical results also demonstrate that relationship between the interface damage level (corresponding to the ultimate tensile loading) and the adhesive thickness is not monotonous. However, as an increase of the adhesive thickness, the uniformity of damage level distribution is enhanced. Furthermore, the variation of the interface damage level with respect to the scarf angle is also not monotonous for each adhesive thickness. It can be concluded that the effects of the scarf angle and the adhesive thickness on the mixed-mode failure of DSJ are coupled rather than independently.