Optimization Design of Unbonded Areas Layout in Titanium Alloy Laminates for Fatigue Performance

This paper proposed a new type of unbonded areas which are preset in diffusion bonding titanium alloy laminates (DB-TAL). A group of DB-TAL specimens with symmetric striped unbonded areas were prepared, and the fatigue experiments under symmetric tension–tension cyclic loading were conducted. The fatigue crack growth behavior was studied from the fracture surface. The results show that this kind of unbonded area can toughen the DB-TAL based on a new mechanism. For the new toughening mechanism, we extracted the key factors in the DB-TAL specimens with symmetric striped unbonded areas and built a simplified model to analyze the key parameters. The results show that the size and location of the unbonded areas are the key factors for the toughening design, and the model we built can efficiently give the optimization design for the DB-TAL specimens with striped unbonded areas.