Equine hoof wall: Structure, properties, and bioinspired designs

Area of Science:

• Biomechanics and Biomaterials
• Hierarchical structures in natural materials
• Bioinspired engineering design

Background:

• The horse hoof wall's exceptional impact resistance is attributed to its complex hierarchical structure.
• Understanding its mechanical properties under dynamic loading is crucial for bioinspired applications.
• Previous studies have not fully elucidated the failure mechanisms or quantified novel structural features.

Purpose of the Study:

• To characterize previously unknown structural features of the horse hoof wall.
• To investigate the hydration-dependent viscoelasticity and failure mechanisms under dynamic loading.
• To design and evaluate bioinspired structures based on hoof wall architecture.

Main Methods:

• Structural characterization using imaging techniques.
• Viscoelasticity testing (creep and relaxation) and modeling (Maxwell-Weichert model).
• Drop tower tests for dynamic impact analysis and fractography.

Main Results:

• Novel tubule bridges were identified and quantified.
• Hydration gradient influences stress distribution; viscoelasticity is described by two relaxation times.
• Hierarchical failure mechanisms revealed: tubules dominate low energy, lamellae dominate high energy impacts.

Conclusions:

• The intertwined nature of tubules and lamellae enhances toughness.
• Bioinspired 3D printed structures with gradient and lamellar features demonstrated improved fracture control and energy absorption.
• The study provides a deeper understanding of hoof wall mechanics for advanced material design.