engleski

STRUCTURES AND MICROHARDNESS OF PINNA PECTINATA SEASHELL’S

The natural structures and materials offer an inspiration for new solutions in the development of advanced engineering cellular and composite materials. The lamellar nacreous (mother of pearl), cross-lamellar and prismatic structures of seashells are especially interesting for development of the biomimetic concepts of nano- and micro- laminate composites. The inner surface layer of narrower part the Pinna Pectinata (Pinnidae)shell has a nacreous structure composed of aragonite platelets surrounded with an organic phase and in the outer layer a polygonal prismatic structure with high ratio length/thickness of columns. The whole crosssection of the upper wider shell part constitutes of the polygonal columnar crystals surrounded with an organic phase as well. Nano- and micro-indentation gives valuable information about the mechanical behaviours particularly by compression, but also by tensile and shear load. The Vickers microhardness of Pinna Pectinata (Pinnidae) Adriatic Sea mollusc shells structure has been determined as a function of the indentation load and loading direction. The load dependence of microhardness is analyzed by using the known Meyer’s law and modified proportional specimen resistance (PSR) model. The best correlation between measured values and used models is achieved by using the modified PSR model. The results show that the measured microhardness depends on the load for the lamellar and prismatic structures, except for the prismatic ones indented perpendicularly to the outer surface.

microhardness; indentation size effect (ISE); seashell structures

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