Indentation experiments and simulation of ovine bone using a viscoelastic-plastic damage model

Area of Science:

• Biomaterials Science
• Orthopedic Biomechanics
• Computational Solid Mechanics

Background:

• Bone exhibits complex viscoelastic and plastic behaviors under indentation, leading to permanent deformation and microcrack-induced damage.
• Existing models often simplify these behaviors, limiting accurate simulation of bone mechanical responses at micro/nanoscales.
• Ovine bone, particularly post-ovariectomy, serves as a relevant model for studying age- and condition-related bone degradation.

Purpose of the Study:

• To develop and validate a simplified viscoelastic-plastic damage model for simulating bone indentation creep.
• To investigate the influence of model parameters on indentation curves.
• To compare the mechanical response and damage progression in baseline versus ovariectomized ovine bone.

Main Methods:

• Development of a simplified viscoelastic-plastic damage model.
• Experimental indentation of baseline and 2-year post-ovariectomized (OVX-2) ovine bone samples.
• Finite element analysis (FEA) to apply the damage model and simulate experimental indentation data.

Main Results:

• The developed model successfully simulated bone indentation creep data.
• Key mechanical properties including yielding, viscosity, and damage parameters were extracted from simulations.
• Ovariectomized (OVX-2) bone samples exhibited more rapid damage development compared to baseline samples under identical indentation loads.

Conclusions:

• The simplified viscoelastic-plastic damage model provides a valuable tool for analyzing bone mechanical properties and damage.
• Ovariectomy significantly accelerates the onset and progression of damage in ovine bone under mechanical stress.
• This model aids in understanding bone fragility and developing targeted interventions for conditions like osteoporosis.