DETERMINATION OF MATERIAL CONSTANTS AND HYDRAULIC STRENGTHENING OF TRABECULAR BONE THROUGH AN ORTHOTROPIC STRUCTURAL MODEL

A statistical mathematical model is used to describe the viscoelastic behavior of trabecular bone from the description of its microstructure . Trabecular bone is regarded as an orthotropic composite material con sisting of two phases: The trabeculae, modelled as a non-linear elasti c material, and the marrow, modelled as a Maxwell element. The macrosc opic constitutive equation contains, as parameters, the constants of t he material phases' constitutive equations, the respective volume frac tions and parameters descriptive of the geometry of trabecular bone. W ith this model, the contribution of the marrow to the mechanical behav ior of trabecular bone is determined and it is calculated that, under a step load and at strain rate, 10 min-1, the marrow can bear about 25 % of the applied load. The constants of the material phases are also c alculated from a series of stress-relaxation curves on trabecular bone specimens. It is concluded that the trabeculae display non-linear ela stic behavior.