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Fragility Assessment of Bovine Cortical Bone Using Scratch Tests
Published on: November 30, 2017
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A critical evaluation of cortical bone fracture toughness testing methods
Daniel Dapaah1, Thomas Willett1
1Systems Design Engineering, University of Waterloo, 200 University Ave. W., Waterloo, Canada.
Journal of the Mechanical Behavior of Biomedical Materials
|August 29, 2022
Summary
The unloading compliance method inaccurately measures cortical bone fracture toughness due to violated assumptions. This leads to significant overestimation, necessitating standardized testing approaches for accurate bone fragility assessment.
Area of Science:
- Biomechanics
- Materials Science
- Orthopedics
Background:
- Cortical bone fracture mechanics is crucial for understanding bone fragility and fracture.
- The J-integral resistance (J-R) curve, based on ASTM E1820, is the standard method.
- This standard uses the unloading compliance (UC) method to estimate crack extension, requiring unload-reload cycles.
Purpose of the Study:
- To investigate the impact of the UC method on the accuracy of fracture toughness measurements in bovine cortical bone.
- To assess the influence of unload-reload cycles and UC-based crack extension estimation on fracture toughness quantification.
Main Methods:
- Bovine cortical bone specimens were subjected to three-point bending fracture tests.
- Paired specimens were divided into cyclic (UC method for crack extension) and monotonic (optical method for crack extension) groups.
- J-R curves were generated using three approaches, and fracture toughness parameters were compared.
Main Results:
- The UC method underestimated crack extension by an average of 73%.
- Combined effects of UC method and unload-reload cycles significantly overestimated fracture toughness measures.
- Significant discrepancies were observed between UC-derived and optical crack extension measurements.
Conclusions:
- The UC method's assumptions are violated by cortical bone, compromising fracture toughness accuracy.
- Standardized fracture testing protocols are needed for reliable assessment of bone mechanical properties.
- Further research is required to develop accurate and standardized methods for cortical bone fracture testing.
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