Mechanics of Bioinspired Lamellar Structured Ceramic/Polymer Composites

Nima Rahbar
Worcester Polytechnic Institute, Massachusetts, United States

Keywords: Super Tough Ceramic Composites

Super-tough ceramics are one of the main goals of materials science. Bioinspired design is shown to be one of the most effective methods in this effort. Previous studies on mechanical performance of biological multilayered materials such as nacre, have shown that their outstanding mechanical properties are direct results of the nanoscale features and optimized arrangement of the elements in their microstructure. In this study, the mechanical performance of bioinspired alumina/polydimethysiloxane (Al2O3/PDMS) and alumina/polyurethane (Al2O3/PU) composite samples with lamellar structure are experimentally and analytically investigated. Bioinspired multilayered samples with micron-size layers were fabricated using the freeze casting technique. Different parameters such as solution concentration, freezing rate and sintering temperature affect the structure, and subsequently, the mechanical performance of these multilayered materials. Fracture mechanics tests were used to find the Resistance-Curve (R-Curve) behavior of the samples. The results show that in Al2O3/PDMS samples, fracture toughness is directly proportional to lamellae thickness while in Al2O3/PU samples, there is an optimum lamellae thickness. The approach used in this study is quite flexible for different material combinations. To fully understand the underlying toughening and deformation mechanisms, a micromechanics model of the mechanical response of lamellar composites is presented.