Biomechanism of impact resistance in the woodpecker’s head and its application

Abstract

The woodpecker does not suffer head/eye impact injuries while drumming on a tree trunk with high acceleration (more than 1000×g) and high frequency. The mechanism that protects the woodpecker's head has aroused the interest of ornithologists, biologists and scientists in the areas of mechanical engineering, material science and electronics engineering. This article reviews the literature on the biomechanisms and materials responsible for protecting the woodpecker from head impact injury and their applications in engineering and human protection. Traumatic brain injury as a consequence of head impact injury has been a leading cause of morbidity and death in war, aviation and road accidents and sports collisions [1][2][3]. However, the woodpecker repeatedly strikes its head against trees without suffering head injury when drumming a trunk continually at a speed of 6-7 m s 1 and acceleration of ~1000×g [4][5][6][7]. The woodpecker rhythmically drums surfaces such as dead tree limbs and metal poles with its beak to catch worms to eat, attract a mate or announce its territorial boundaries [7,8]. The woodpecker's resistance to head impact injury is a prime example of adaptive natural evolution over millions of years [9], and has been of interest not only to ornithologists and biologists but also to researchers in the fields of mechanical engineering, medical engineering, material science and electronics engineering [4][5][6][7][10][11][12][13].Researchers have explored the mechanism of how a woodpecker avoids head impact injury [4][5][6]14,15] and searched for clues that will help in developing a bionics shock-absorbing system or device for engineering purposes or human protection [10][11][12][13]. This paper presents an overview of the biomechanism that prevents the woodpecker from suffering head impact injury and its applications.

Effect of Microstructure of Spongy Bone in Different Parts of Woodpecker’s Skull on Resistance to Impact Injury

“…At the interface between the cartilagebone skeleton and the tissue layer, there is a hierarchical fiber connection [15]. The cranial bone of the woodpecker achieved a higher ultimate strength of 6.38 MPa compared with the Lark of 0.55 MPa [6,33,34], which suggested that the mechanical properties are sensitive to the shape of individual trabeculae [35]. Materials that contain more organic material are expected to exhibit greater flexibility under load [36][37][38][39][40].…”

“Tighter fit” theory—physiologists explain why “higher altitude” and jugular occlusion are unlikely to reduce risks for sports concussion and brain injuries

“…Woodpeckers are commonly cited as the inspiration for the theorized protective effects of "tighter fit," based on their limited intracranial space (24,27). However, it seems scientifically implausible for slight increases in cranial fluid volume to functionally mimic woodpeckers' "unique anatomic structure," which includes numerous macroscopic (i.e., brain structure and orientation, skull thickness) and microscopic (i.e., various trabecular and biochemical qualities that influence mechanical properties) anatomic adaptations that collectively create impact-resistance (28). A jugular occlusion study in rats reporting decreased brain damage (24, 27) after a 900 g impact ( 15) has been used to justify its potential in sports (16,25).…”

A Review of Bioinspired Vibration Control Technology

“…In this process, acceleration can reach 1000 times the acceleration of gravity, and velocity can reach six times the speed of sound [34]. However, the vibration caused by the strong impact does not damage or destroy the woodpecker's brain [35][36][37]. Therefore, it is one of the important development directions of current vibration control systems [38][39][40][41], which can simulate biological structures and functions in order to improve the performance of traditional vibration control devices.…”