A nonlinear micromechanical model for vertebral trabecular bone and application in whole bone finite element analysis

摘要

Trabecular bone has a porous open-celled network of bone tissue in which the basic symmetry of the microstructure depends on the loading environment. Including the trabecular bone component in a finite element model of a whole bone presentsconsiderable challenges. The problem can be greatly simplified by representing the trabecular bone as a cellular solid, or foam, in which it is assumed that the structure has a regularly repeating unit-cell (Gibson,1985). This study uses the foam analogyfor vertebral trabecular bone, where the architecture is modeled as a regular hexagonal open-celled foam. A nonlinear constitutive model has been developed, where nonlinearity is introduced as coupled elasto-plastic beam behavior of individual trabeculaewithin the local unit cell. The constitutive equations are defined in terms of the architecture and the material properties, so that the effects of age-related changes in the trabecular architecture may be studied. Nonlinear (elasto-plastic) 3-D finiteelement analyses of compression of a whole vertebral body with the foam model for the trabecular core were conducted. The ultimate loads predicted by the model compare very well with experimental results of other researchers.