Joint Materials/Solid Mechanics Seminar Series
“Bio-Inspired Structural Materials”
Robert O. Ritchie
Department of Materials Science and Engineering, University of California Berkeley
and
Materials Sciences Division, Lawrence Berkeley National Laboratory
Abstract:
The structure of materials invariably defines their mechanical behavior. However, in most materials, specific mechanical properties are controlled by structure at widely differing length scales. Nowhere is this more apparent than with natural materials. Bone and nacre, for example, are complex composites whose unique combination of mechanical properties derives from an architectural design that spans nanoscale to near-macroscopic dimensions. Unlike engineering composites where properties are invariably governed by the rule of mixtures, the mechanical properties of natural composites are generally far greater than their constituent phases. Here we describe an approach to developing bulk ceramic-polymer nacre/bone-like structural materials with unprecedented strength/toughness properties. We attempt to emulate Nature using a freeze-casting process to make materials through the combination of two ordinary compounds, alumina and PMMA, into ice-templated structures with exceptional fracture toughness, an order of magnitude higher than that of their constituents. The final products are bulk lightweight hybrid ceramic-based materials whose high specific strength and toughness properties are comparable to aluminum alloys.
Monday, March 8, 2010 4:00-5:00 pm B&H Room 190
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