An improved understanding of fatigue crack growth behavior of multiple collinear cracks in hybrid composite structures

Accurately predicting MSD crack growth behavior in hybrid metal–composite structures is challenging due to the complex interactions of fiber bridging and delamination failure in fiber–metal laminates (FMLs). These mechanisms enhance damage tolerance but complicate crack analysis. This paper proposes two analytical models to address crack growth in FMLs with multiple collinear cracks. The first model analyzes crack openings and stress intensity factors (SIFs) for multiple cracks, capturing the physics of MSD cracking, but it is cumbersome to implement. The second model simplifies the problem by considering energy dissipation, treating the MSD scenario as a single crack in a finite plate and equating the energy dissipation between both cases. Both models were validated and show accurate predictions of crack growth behavior, capturing crack acceleration effectively. The results emphasize the importance of accounting for the contributions of bridging and stiffening mechanisms in FMLs, particularly load redistribution, which influences crack growth.