THE MECHANICAL-PROPERTIES OF NATURAL MATERIALS .2. MICROSTRUCTURES FOR MECHANICAL EFFICIENCY

Many natural materials have exceptionally high values of the mechanica l performance indices described in the previous, companion paper. For beams and plates of a given stiffness or strength, or for a column of a given buckling resistance, woods, palms and bamboo are among the mos t efficient materials available. Their mechanical efficiency arises fr om their combination of composite and cellular microstructures. In thi s paper we analyse the microstructures which give rise to exceptional performance, describe the fabrication and testing of model materials w ith those microstructures and discuss the implications for design of m echanically efficient engineering materials.