Effect of microstructure of spongy bone in different parts of woodpecker's skull on resistance to impact injury

Natural biological materials such as bone, teeth and nacre are nano-composites of protein and mineral frequently exhibit highly superior strength for self-assembly and nanofabrication. Mineral mass and microstructure/nanostructure of bone are susceptible to stimulation by mechanical loads, ensuring that its mechanical behavior and strength are adapted to environmental changes. Woodpeckers repeatedly drum tree trunks at a speed of 6-7 m s-1and acceleration of 1000 g with no head injuries. The uneven distribution of spongy bone has been founded on woodpecker's skull in our previous study. More knowledge of the distribution of the shock-absorbing spongy bone could be incorporated into the design of new safety helmets, sports products, and other devices that need to be able to resist the impact. In this study, the effect of microstructure of spongy bone in different parts on woodpecker's skull compared with other birds was observed and analyzed. It was found that the unique coordinate ability of micro-parameters in different parts of woodpecker's skull could be one of the most important roles of its resistance to impact injury. Better understanding of the materials would provide new inspirations of shock-absorbing composite materials in engineering.