Determining effective centroid position in biomechanical testing: a technique for simplifying whole bone analysis.

This research introduces a simplified method for calculating the position of the effective centroid, modulus of elasticity, and equivalent uniform strain magnitude in a cross-section of bone using a simple whole bone compressive test, saving both implementation complexity and cost.

Methods Used

The research involved the use of:

• A linear beam theory in combination with simple planer geometry theory for the simplification of section response to load.
• Three longitudinal strain gauges fixed around the test specimen cross section of interest. The positioning of the gauge was not necessary for the calculation.
• A simple four-point loading jig for undertaking the sample loading.

Result Analysis

The testing was done on:

• An object with well-known elasticity and geometry, which was an aluminium tube, to act as the control group in the experiment.
• Seven pairs of equine third metacarpal whole bones to ensure reliability of results.

The results indicated that average cross-sectional modulus of elasticity, equivalent uniform cross-sectional strain, and effective centroid locations were predicted accurately within the range of published values.

Conclusion

From the findings, the research concluded that the testing setup and analysis technique introduced were cost-effective and simplified compared to the formerly available techniques. Thus, this technique for determining the effective centroid position in biomechanical testing could be of immense help in whole bone analysis, especially when dealing with factors like sample asymmetry, heterogeneous material properties, and unknown effective centroid location that typically complicate the process.