Wood: wood, bamboo mechanics
Amada, S. and Lakes, R. S., "Viscoelastic properties of bamboo", Journal of Materials Science, 32, 2693-2697, (1997). Dynamic viscoelastic properties of bamboo were determined in torsion and bending. Damping, measured by tan delta, in dry bamboo was relatively small, about 0.01 in bending and 0.02 to 0.03 in torsion, with little dependence on frequency in the audio range. In wet bamboo, damping was somewhat greater: 0.012 to 0.015 in bending and 0.03 to 0.04 in torsion. The anisotropy in damping implies a purely cellular model is insufficient; there is large scale molecular orientation or at least two distinct solid phases. Get pdf.
Wood, with S. Cramer, D. Kretschmann The overall hypotheses of this research are that: The mechanical properties of earlywood compared to latewood are dramatically different in loblolly pine plantation wood. The mechanical properties and their variations of earlywood and latewood can be quantified and characterized. These mechanical properties of earlywood and latewood vary with location within a tree and conditions of growth. Ultimately, the properties of earlywood and latewood can be used to explain previously unexplained variation in wood product performance. Among other things, we are conducting research into the mechanical properties of slices of individual growth rings, using our micromechanics apparatus for broadband viscoelastic spectroscopy (BVS).
Kretschmann, D. E., Schmidt, T. W., Lakes, R. S., and Cramer, S. M., "Micromechanical measurement of wood substructure properties", Society of Experimental Mechanics Annual Conference, Milwaukee, WI, June 10-11 (2002). Get pdf.
Cramer, S., Kretschmann, D., Lakes, R. And Schmidt, T. "Mesostructure Elastic Properties in Loblolly Pine," Proceedings of the 4th Plant Biomechanics Conference, Michigan State University, East Lansing, MI, 21-25 July (2003). Get pdf
Cramer, S. M., Kretschmann, D. E., Lakes, R. S., and Schmidt, T. W. "Earlywood and latewood elastic properties in loblolly pine", Holzforschung, 59, 531-538 (2005). The elastic properties of earlywood and latewood and their variability were measured in 388 specimens from six loblolly pine trees in a commercial plantation. Properties measured included longitudinal modulus of elasticity, shear modulus, specific gravity, microfibril angle, and presence of compression wood. Novel testing procedures were developed to measure properties from specimens of 1 mm x 1 mm x 30 mm from earlywood or latewood. The elastic properties varied substantially circumferentially around a given ring and this variation was nearly as large as the variation across rings. The elastic properties varied by ring and height, but while the modulus of elasticity increased with height, the shear modulus decreased with height. A strong correlation was found between modulus of elasticity and shear modulus, but only at low heights and inner rings. Specific gravity and microfibril angle were the strongest predictors of elastic properties and explained 75 percent of the variation in modulus of elasticity for latewood. Despite being the best predictors in this study these parameters accounted for less than half of the variability of earlywood modulus of elasticity, earlywood shear modulus and latewood shear modulus. Get pdf
Kretschmann, D. E., Cramer, S. M., Lakes, R. S., and Schmidt, T. W. "Selected mesostructure propertes in loblolly pine from Arkansas plantations", Chapter 12, p. 147-170, in Characterization of the Cellulosic Cell Wall, ed..D. D. Stokke, L. H. Groom, Blackwell, Oxford, UK, (2006).