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 KEYNOTE AND INVITED SPEAKERS |
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| Full name of the keynote speaker |
Marc Andre Meyers
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Company |
California University
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Department |
Materials
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| Summary keynote speaker resume |
Professor of Materials Science, UC San Diego. Mechanical Engineering degree from UFMG and Ph. D. from the U. of Denver. Co-founder and Associate Director of the Center for Explosives Technology Research in Socorro, New Mexico. Co-founder and co-chair of the EXPLOMET conference series (1980, 1985, 1990, 1995, 2000). Advisor to the Director, Materials Science Division, US Army Research Office (1985-1987), actively engaged in stimulating and directing research in the dynamic behavior of materials. Associate Director and Director, Institute for Mechanics and Materials (1992-1997). Through a 30-year effort, he has unified the field of mechanical behavior of materials and significantly enhanced its visibility in the materials community. Research interests range from dynamic processing (explosive consolidation, synthesis, welding, shock- and shear induced reactions, and combustion synthesis), dynamic fracture and fragmentation, dynamic and shock response of materials, martensitic transformations, twinning, constitutive equations, effect of grain size on the strength of metals, nanostructured materials, and biological materials. Fellow of ASM International, Humboldt Senior Scientist Award recipient, Structural Materials Division (TMS) Distinguished Scientist/Engineer Award. Author or co-author of 280 research papers, three books; co-editor of seven books.
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Title of the lecture |
Structural Biological Composites
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Summary of the spoken topic |
Most natural (or biological) materials are complex composites whose mechanical properties are often outstanding, considering the weak constituents from which they are assembled. These complex structures, which have risen from millions of years of evolution, are inspiring Materials Scientists in the design of novel materials. The three defining characteristics, hierarchy, multifunctionality, and self healing capability, are illustrated. The basic building blocks are described with emphasis on chitin, keratin, elastin, collagen, and mineral phases. The defining mechanical characteristics and structures of biological ceramics, polymer composites, elastomers, and cellular materials are presented. Selected systems in each class are described with emphasis on the relationship between their structure and mechanical response. The author?s research on the conch and shells, toucan beak, and crab exoskeleton will be highlighted.
Shells: The growth of the aragonite component of the abalone shell occurs by the successive arrest of growth by means of a protein-mediated mechanism; this is followed by the reinitiation of growth. This takes place in the ?Christmas-tree pattern?. The calcium and carbonate ions can penetrate through the organic layer deposited by the epithelium. The growth of the nacreous layers (aragonite) was observed by trepanning the shell and enabling the extrapallial layer to construct the ceramic for different time periods, removing them, and observing them by scanning electron microscopy.
Tou Toucan beak: The structure of a Toco Toucan was found to be a sandwich composite with an exterior of keratin and a fibrous network of closed cells made of calcium-rich proteins. The keratin layer is comprised of superposed hexagonal scales (50 µm diameter and 1 ?m thickness) glued together. The interior of the beak is comprised of a cellular structure. Its density is on the order of 0.04.Thus, the overall density of the beak is approximately 0.1. it is shown by analysis and computations that this structure is optimized for weight and stiffness.
Crab: The exoskeleton of the sheep crab (Loxorhynchus grandis) claw consists of a complex network of highly mineralized chitin rods in a Bouligand [26] pattern interwoven with flexible fibers that ?stitch? the structure together. It is a hierarchically structured ceramic-polymer composite. A Bouligand (helical stacking) arrangement provides structural strength that is in-plane isotropic in spite of the anisotropic nature of the individual bundles. Canals enveloped in tubules are formed along the direction perpendicular to the exoskeleton plane. These tubules are hollow and have a flattened configuration that twists in a helical fashion. They fail in a ductile mode and ?stitch? together the brittle bundles arranged in the Bouligand pattern, providing toughness to the structure. They also play a role in keeping the exoskeleton in place even when it is fractured, allowing for self healing.
Support: National Science Foundation Ceramics Program, Division of Materials Research.
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