Bio-inspired composites with functionally graded platelets exhibit enhanced stiffness

Unidirectional composites inspired from biological materials such as nacre are composed of stiff platelets arranged in a staggered manner within a soft matrix. Elaborate analyses have been conducted on the aforementioned composites and they are found to have excellent mechanical properties like stiffness, strength and fracture toughness. The superior properties exhibited by these composites have been proved to be the result of its unique structure. An emerging development in the field of composite structures is functionally graded composites, whose properties vary spatially and possess enhanced thermo-mechanical properties. In this paper, the platelets are functionally graded with its Young's modulus varying parabolically along the length. Two different models-namely, tension shear chain model and minimisation of complementary energy model have been employed to obtain the stiffness of the overall composite analytically. The effect of various parameters that define the composite model such as overlapping length between any two neighbouring platelets, different gradation parameters and platelet aspect ratio on the overall mechanical properties have been studied. Composites with functionally graded platelets are found to possess enhanced stiffness (upto [Formula: see text] higher) for certain values of these parameters. The obtained solutions have been validated using finite element analysis. Bio-inspired composites with functionally graded platelets can be engineered for structural applications, such as in automobile, aerospace and aircraft industries, where stiffness plays a crucial role.