Mode I Fracture, Fatigue, and Interface Toughening in Ti/Al Laminates Using Alumina With Pineapple–Carbon Fiber Reinforcement

ABSTRACT Facesheet selection and alumina‐modified adhesive were examined as coupled design variables controlling the mechanical response of dual‐metal 3/2 Ti/Al fiber–metal laminates reinforced with pineapple–carbon hybrid fibers. Titanium‐ and aluminum‐skinned laminates containing 0, 2, 3, and 4 wt.% Al 2 O 3 in the epoxy bondline were evaluated under tensile loading, Mode I fracture, tension–tension fatigue, and Izod impact. Titanium‐skinned laminates consistently exhibited higher stiffness, tensile strength, fracture resistance, and fatigue life. At 4 wt.% Al 2 O 3 , the ultimate tensile strength reached ~1.2 GPa and fracture initiation toughness increased to ~330–360 kJ m −2 , with fatigue life of ~6.1 × 10 5 cycles at 60% of ultimate strength. Aluminum‐skinned laminates absorbed higher impact energy, peaking near ~80 J at moderate alumina contents due to greater facesheet plasticity. Alumina addition enhanced interfacial load transfer and delayed debonding, revealing a mode‐dependent design window for durability‐ or impact‐driven applications.