Dynamical study of couple stress effects in human compact bone

Area of Science:

• Biomechanics
• Materials Science
• Human Anatomy

Background:

• Human compact bone exhibits complex mechanical properties.
• Couple-stress theory provides a framework for materials with microstructure.
• Osteons represent a key structural feature influencing bone mechanics.

Purpose of the Study:

• To investigate couple stress effects in wet human compact bone using torsional resonance.
• To determine the characteristic length parameter in bone and its frequency dependence.
• To analyze the influence of couple-stress on stress concentration factors.

Main Methods:

• Torsional resonance experiments were conducted on wet human compact bone specimens.
• Analysis involved applying couple-stress theory to experimental data.
• Measurements were taken across a range of frequencies.

Main Results:

• Couple stress effects were identified in the torsional response of wet human compact bone.
• The characteristic length was found to be on the order of osteon size.
• A decrease in characteristic length was observed at higher frequencies compared to lower frequencies.
• Couple-stress effects were shown to reduce stress concentration factors around holes.

Conclusions:

• Couple stress is a significant factor in the mechanical behavior of human compact bone.
• The frequency-dependent characteristic length suggests microstructural rearrangements or altered responses at different frequencies.
• Understanding couple-stress effects is crucial for predicting bone's mechanical integrity, especially in the presence of defects like holes.