Viscoelastic effects during depth-sensing indentation of cortical bone tissues

When using nanoindentation to measure the mechanical properties of biological tissues, viscoelastic effects may be significant and may affect the accuracy of the results. In this study, a method for correcting viscoelastic effects during nanoindentation is described. The correction formula involved is re-derived using a three-element nonlinear visco-plasto-elastic material tensor model. This method is then applied to forelimb and femur bone samples taken from two species (C57 BL/6N and ICR) of mice. After correcting for viscoelastic effects, elastic modulus and hardness results are found to be independent of experimental conditions, such as the unloading rate. Measured mechanical properties also correlate well with the calcium content of the bone samples.link_to_subscribed_fulltex