Effect of hydration on mechanical characteristics of pangolin scales

As a typical keratinous material, the mechanical properties of pangolin scales are affected by hydration. Clarifying the mechanism of influence of hydration on dynamic response of materials may provide valuable inspiration for bio-inspired design. In this study, mechanical properties and impact wear behaviors of pangolin scales from different hydrated levels were investigated on a low-velocity impact wear tester. The dynamic response and damage behavior of these pangolin scales were systematically analyzed. Results showed that the energy absorption and impact contact force were considerably distinct with different hydrated levels. The maximum values of the impact contact force are similar to each other in various impact cycles. However, the damage extent of scales was not the same in varied impact cycles. Impact worn scars size of scales increased as the impact cycles increased. Under varied hydrated levels, energy absorption initially decreased and then increased with the increase in moisture content. Specifically, for a hydrated level of 10.5%, the energy absorption had the lowest rate, down to 26.6%, and the impact force decreased. Finally, the mechanisms and factors affecting the dynamic response and impact wear of scales were investigated. This study promoted a bio-inspired design for improving impact wear resistance properties.