The subcritical debond growth of the Al-epoxy interface under fatigue loading is characterized by using a novel mixed-mode bending (MMB) apparatus that allows quantifying the debond behavior under a full spectrum of loading mode mixity.Steady-state response of fatigue debond propagation under a constant loading phase angle between 0° and 60° was fitted to the applied strain energy release rate range by using a power-law relationship.It was found that the exponent of the power-law model decreases as the phase angle increases.A general phase-angle dependent mathematical model was eonstructed to describe the fatigue delamination growth rate of the Al-epoxy interface under mixed-moded loading.The subcritical debond growth model can be combined with delamination driving forces obtained for real structures containing the Al-epoxy interface to predict the fatigue crack growth behavior and the corresponding structural reliability.