Dynamic fracture resilience of elk antler: Biomimetic inspiration for improved crashworthiness
The antler of the North American elk has been shown to have impressive fracture resistance under quasi-static loads, but given its viscoelastic behavior and impact nature of loading, questions remain as to its mechanical, and in particular, fracture behavior under dynamic loading. Samples were tested using a unique split-pressure Hopkin-son bar (SPHB) for four-point bending experiments in order to measure the fracture toughness of this material Interestingly, the hierarchical structure of antler had a strong influence on crack propagation characteristics, and cracks tended to propagate along the osteonal growth direction, whether loaded parallel or perpendicular to the osteonal growth direction. This occurred to such a degree so as to stop all crack propagation through the sample on transverse specimens, thus inhibiting the ability to measure a valid crack initiation toughness and demonstrating the extreme resilience of antler to resist dynamic fracture. The high resilience of antler to impact loading may serve as biomimetic inspiration to future material development for crashworthiness and defense applications.
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