| Estimates are presented of the elastic constants at the level of a collagen fibril whose diameter is the order of 20 nm, of a collagen fiber whose diameter is the order 80 nm, and a single lamella, which is composed of multiple collagen fibers' layer; the thickness of one collagen fiber layer is the order of 130 nm.; The anisotropic poroelastic constants of an osteon are estimated: The drained elastic constants are the porous medium's elastic constants when the fluid in the osteonal pores easily escapes and the pore fluid can sustain no pore pressure. The drained elastic constants at the lacunar-canalicular porosity tissue level are estimated by using an effective moduli model in which the shape of lacunae is approximated as ellipsoidal cavities. The undrained elastic constants are the porous medium's elastic constants when the medium is fully saturated with pore fluid and the fluid cannot escape, are also estimated.; A method is illustrated for determining the effective transversely isotropic (or isotropic) elastic constants from measured orthotropic elastic constants. This method consists of constructing upper and lower bounds on the effective transversely isotropic (or isotropic) elastic constants using the known orthotropic values. Fortunately, the upper and lower bounds are very close. Thus very good approximations for the effective transversely isotropic (or isotropic) elastic constants for cortical and cancellous bone are obtained from previously published data on the orthotropic elastic constants for those tissue types.; This dissertation is undertaken to build a greater database for the anisotropic elastic constants of bone with the intention of employing them in an anisotropic bone poroelastic model. |
