title: Irregularities of crystallographic orientation and residual stresses in the crossed-lamellar shell as a natural functionally graded material.
abstract: The microstructures of different groups of molluscs are characterized by preferential orientations of crystallites (texture), leading to a significant anisotropy of the physical properties of the shells. A complementary characteristic, usually neglected, is the distribution of the residual stresses existing within the shell wall. By means of X-ray diffraction, we study the distribution of stresses with thickness in the shell wall of the gastropod Conus marmoreus, which has a microstructure of the crossed-lamellar type. The results revealed an extraordinary texture inhomogeneity and the existence of tensional residual stresses along the shell thickness, the origins of which are unknown. Some of the observed changes in textural parameters and stresses coincide with the transitions between shell layers, although other features are of unknown origin. Our results provide insight into the microstructural regularities that govern the mesoscale construction of shells, such as that of C. marmoreus.
authors.affiliation: Institute of Metallurgy and Materials Science of the Polish Academy of Sciences, 25 Reymonta Strasse, Kraków 30-059, Poland j.bonarski@imim.pl.
authors.forename: Jan T
authors.initials: JT
authors.lastname: Bonarski
authors.affiliation: Departamento de Estratigrafía y Paleontología, Facultad de Ciencias, Universidad de Granada, Avenida Fuentenueva s/n, Granada, Spain.
authors.forename: Antonio G
authors.initials: AG
authors.lastname: Checa
authors.affiliation: Departamento de Mineralogía y Petrología, Universidad de Granada, Campus de Fuentenueva, Granada, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Rodriguez-Navarro
authors.affiliation: Institute of Metallurgy and Materials Science of the Polish Academy of Sciences, 25 Reymonta Strasse, Kraków 30-059, Poland.
authors.forename: Leszek
authors.initials: L
authors.lastname: Tarkowski
authors.affiliation: Institute of Metallurgy and Materials Science of the Polish Academy of Sciences, 25 Reymonta Strasse, Kraków 30-059, Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Wajda
mesh_terms: D060105:Animal Shells / Q000737:chemistry* / Q000648:ultrastructure*; D000818:Animals; D052078:Conus Snail / Q000737:chemistry* / Q000648:ultrastructure*; D014961:X-Ray Diffraction
keywords: crossed-lamellar structures; crystallographic texture; functionally graded bio-materials; mollusc shell; residual stresses