Experimental characterization of biphasic materials using rate-controlled Hertzian indentation

Area of Science:

• Biomaterials Science
• Mechanical Engineering
• Computational Mechanics

Background:

• Characterizing biphasic materials is crucial for understanding tissue mechanics.
• Current methods like linear biphasic theory (LBT) and tension-compression nonlinear biphasic theory (TCN) are computationally intensive and time-consuming.
• There is a need for more efficient and sensitive techniques to analyze biphasic material properties.

Purpose of the Study:

• To introduce and validate a novel Hertzian biphasic theory (HBT) method for biphasic material characterization.
• To compare the performance of HBT against established methods (LBT and TCN).
• To highlight the practical advantages of HBT, including reduced time and computational demands and increased surface sensitivity.

Main Methods:

• Development of a new characterization method based on Hertzian biphasic theory (HBT).
• Indentation experiments performed on a single osteochondral plug.
• Validation of HBT by comparing results with linear biphasic theory (LBT) and tension-compression nonlinear biphasic theory (TCN).

Main Results:

• HBT yielded aggregate moduli (H) of 0.47 MPa, comparable to LBT (0.47 MPa) and TCN (0.40 MPa).
• Permeability (k) values from HBT (0.0026 mm⁴/Ns) were consistent with LBT (0.0014 mm⁴/Ns) and TCN (0.0016 mm⁴/Ns).
• Tensile moduli (E) obtained by HBT (8.7 MPa) showed good agreement with TCN (10.3 MPa), though differing from LBT (0.46 MPa).

Conclusions:

• The Hertzian biphasic theory (HBT) method is a valid and effective approach for characterizing biphasic materials.
• HBT offers significant practical advantages, including reduced time and computational requirements.
• The study supports the adoption of HBT for its efficiency and sensitivity in material property analysis.