Volume effects on yield strength of equine cortical bone

Area of Science:

• Biomechanical Engineering
• Materials Science
• Orthopedic Research

Background:

• Structural failure is fundamentally influenced by volume effects, where material properties depend on specimen volume.
• Brittle materials, like ceramics, show volume effects due to critical flaws within the stressed volume.
• These volume effects have been suggested to impact the mechanical properties of bone.

Purpose of the Study:

• To investigate the hypothesis that smaller volumes of cortical bone exhibit greater yield strengths than larger volumes.
• To determine if specimen volume accounts for significant variability in yield strength, comparable to microstructural features.

Main Methods:

• Monotonic tensile testing of equine third metacarpal diaphyseal specimens (n=24).
• Specimens varied in nominal cross-sections (3x4 mm) and gage lengths (10.5, 21, 42 mm) to alter specimen volume.
• Analysis of yield strength in relation to specimen volume and cumulative failure probability.

Main Results:

• Yield strength was significantly greater in the smallest volume specimens compared to the largest.
• Data followed a two-parameter Weibull distribution, with log yield strength positively correlated with cumulative failure probability.
• Log yield strength was negatively correlated with log volume, supporting the volume effect hypothesis.

Conclusions:

• Small stressed volumes of cortical bone possess greater yield strength than large stressed volumes.
• Specimen volume is a critical factor influencing the yield strength of cortical bone.
• Understanding volume effects is crucial for accurate biomechanical analysis and predicting failure in bone structures.