Micromechanics Modeling and Analysis of Haversian Compact Bone Tissues as a Fiber Reinforced Composite Material

Abstract

Abstract : Haversian compact bone tissue is being studied theoretically and experimentally to characterize its behavior as a fiber reinforced composite material with the aim of biomimicking its salient features. Analytical and finite element based composite micromechanics techniques have been developed and evaluated for theoretical modeling of structure/property relationships. two-dimensional finite element models of material representative volume elements have been used to predict variations in macroscopic mechanical properties with porosity, constituent properties, and fiber/matrix interface conditions. Mori-Tanaki effective medium methods have also been examined. Haversian compact bone possesses a distinct interphase' material surrounding each osteon called the cement line. The role and properties of the cement line are of particular interest for possible biomimicking. Mechanical testing of bone specimens is accompanying the theoretical work to provide data for verification and model improvement. Anisotropic elastic moduli have been measured using through-transmission ultrasound. Longitudinal tensile strength and elastic modulus have been determined from quasi-static tensile testing. In addition, dynamic mechanical testing has been initiated to measure viscoelastic properties. (storage & loss moduli, loss factor). Testing results are also being correlated with quantitative microstructural measures. The parameters of interest include bulk density (wet & dry), mineralization (ash), porosity, osteon area fraction, and total cement line perimeter (per unit area). Additional dynamic testing is continuing to more definitively determine the influence of the cement line on properties.