Damping characteristics of woodpecker inspired layered shock absorbing structures

Abstract

A woodpecker can drum the surface of a tree at a rate of 18 to 22 times per second with a deceleration of 1200 g without experiencing any blackout or brain damage. A woodpecker is able to do this because of its unique head structure (beak, hyoid, spongy bone and skull bone with cerebrospinal fluid). A novel woodpecker beak inspired shock absorbing structure comprising of different layers like steel, foam, aluminium and a core containing beads was fabricated. It is then subjected to free vibration analysis considering the beam as cantilever structure. The logarithmic decay curve for each component was plotted using software integrated with the vibration test apparatus. Values for damping were found out for each layer as well as combination of different layers. Damping values obtained were then compared. The increased damping properties can find applications in developing impact shock resisting structures and hybrid shock absorber design.