Dynamic impact testing of hedgehog spines using a dual-arm crash pendulum

Hedgehog spines are a potential model for impact resistant structures and material. While previous studies have examined static mechanical properties of individual spines, actual collision tests on spines analogous to those observed in the wild have not previously been investigated. In this study, samples of roughly 130 keratin spines were mounted vertically in thin substrates to mimic the natural spine layout on hedgehogs. A weighted crash pendulum was employed to induce and measure the effects of repeated collisions against samples, with the aim to evaluate the influence of various parameters including humidity effect, impact energy, and substrate hardness. Results reveal that softer samples—due to humidity conditioning and/or substrate material used—exhibit greater durability over multiple impacts, while the more rigid samples exhibit greater energy absorption performance at the expense of durability. This trend is exaggerated during high-energy collisions. Comparison of the results to baseline tests with industry standard impact absorbing foam, wherein the spines exhibit similar energy absorption, verifies the dynamic impact absorption capabilities of hedgehog spines and their candidacy as a structural model for engineered impact technology. •The impact energy absorption capability of hedgehog spines is demonstrated.•Parametric studies on humidity condition, impact speed, and substrate material.•Humidity softens keratin, making spines more durable but less energy absorbent.•Greater impact speed decreases durability, but not initial energy absorption.•Softer, elastic substrate adds energy absorption but samples deform more rapidly.