Mode II delamination of carbon-glass fiber/epoxy hybrid composite under fatigue loading.

• The mechanistic model proposed was unable to evaluate and predicts mode II fatigue crack propagation based on fracture mechanisms. • The analytical model described the energy release of the hybrid composite, evidencing greater energy available for fatigue delamination growth. • The hybrid composite exhibits higher resistance of damage propagation in the shear mode associated with rougher fractured surfaces of hybrid composites. • The proposed mechanistic model evidences each reinforcement contribution to the damage propagation, with similar results at microscopic and macroscopic levels. This work proposes a mechanistic model to evaluate and characterize the mode II delamination of carbon-glass/fiber hybrid composites under fatigue loading. To this aim, crack growth was investigated at microscopic and macroscopic levels to measure the delamination propagation based on fracture mechanisms. The energy balance principle method described the energy release of the hybrid composite, evidencing greater energy available for fatigue delamination growth. The physics-based explanation for this enhancement is associated with the rougher fractured surface (tortuous propagation) due to the change in crack direction in the two reinforcements, stiffness synergy between the two fibers, and the silane coupling agent at the glass fiber surface. The proposed mechanistic model was used to analyze the physical-based behavior of the delamination of the hybrid and non-hybrid laminates, evidencing the contribution of each reinforcement to the SERR, with similar results at microscopic and macroscopic levels. [ABSTRACT FROM AUTHOR]