A two-layer elasto-visco-plastic rheological model for the material parameter identification of bone tissue

Area of Science:

• Biomechanics and Biomaterials Science
• Orthopedic Research
• Materials Science

Background:

• Accurate measurement of bone tissue material properties is crucial for disease diagnosis and material modeling.
• Bone exhibits complex mechanical behavior including viscoelasticity, ductility, and damage, making property quantification challenging from standard stress-strain data.
• Existing methods struggle to isolate individual constitutive effects like stiffness and damping in bone.

Purpose of the Study:

• To develop and validate a methodology for quantifying bone material properties from a single cyclic tensile test.
• To identify stiffness, damping, yield stress, and hardening coefficients of bone tissue.
• To utilize a two-layer elasto-visco-plastic rheological model for this purpose.

Main Methods:

• A novel methodology employing a two-layer elasto-visco-plastic rheological model was developed.
• An inverse approach was used, optimizing model parameters to fit experimental cyclic tensile test data.
• The method was applied to individual bone trabeculae tested under wet conditions.

Main Results:

• The model successfully reproduced pre- and post-yield responses of bone trabeculae, achieving a root-mean-square error of 2.91 ± 1.77 MPa.
• Identified material properties included long-term (3.64 GPa) and instantaneous (5.61 GPa) Young's moduli.
• A yield stress of 16.89 MPa and a loss tangent of 0.04 were determined, with the latter in good agreement with existing literature.

Conclusions:

• The proposed inverse rheological modeling approach effectively quantifies multiple bone constitutive properties from a single mechanical test.
• This method offers a significant advantage for detailed material characterization of bone tissue.
• The findings contribute to improved understanding of bone mechanics for clinical and research applications.