Modeling the tensile behavior of the cement-bone interface using nonlinear fracture mechanics.

The tensile mechanical behavior of the cement-bone interface where there was a large process (plastic) zone at the interface was modeled using a nonlinear fracture mechanics approach. A finite element method was employed, which included a piecewise nonlinear interface, to investigate the behavior of experimental cement-bone test specimens and an idealized stem-cement-bone (SCB) structure. The interface model consisted of a linear elastic region with high stiffness until the yield strength was reached, followed by an exponential softening region, until zero stress. The yield strength and rate of exponential softening after yielding at the cement-bone interface were shown to have a marked effect on the structural stiffness of the SCB model. The results indicate that both yield strength and postyield behavior should be included to characterize the mechanics of the cement-bone interface fully.