Tensile Deformation Law and Scale Effect of Low-Constraint Ultra-Thin Fiber Metal Laminates

Fiber metal laminates (FMLs), as a hybrid composite material, combine the advantages of toughness and impact resistance of metal materials and high strength and low density of fiber composites, and are widely used in the manufacture of large-size parts such as fuselage and skin. The thickness of the metal layer of traditional FMLs is 0.2–0.5 mm, and in this paper, ultra-thin industrial pure titanium grade 1 (TA1)/carbon fiber reinforced polymer (CFRP) laminates will be prepared using TA1 with a thickness of only 0.04 mm. Under the influence of the scale effect, the micro-forming of ultra-thin laminates is quite different from the existing forming theory. Meanwhile, as the thickness of the metal layer decreases to the micrometer level, the effect of grain size on the forming performance of FMLs has not been studied, and the deformation law is unclear. Based on this, in this paper, two processes of low constraint and curing are used to prepare ultra-thin TA1/CFRP laminates. Through comparing the tensile strength and elongation of specimens with different temperatures, lay-up structures, tensile speeds, geometries, and grain sizes, the fracture morphology and failure modes of the laminates were analyzed from both macroscopic and microscopic perspectives. The tensile deformation law of ultra-thin TA1/CFRP laminates is obtained, which provides a theoretical basis for micro-forming of FMLs.