啄木鳥頭部隔震效果之仿生研究

Abstract

在人類的科技發展的過程中，人類總是不斷的從大自然中得到新的構想，這也是所謂的仿生學，其中啄木鳥就是大家極感興趣的題目之一，因為啄木鳥在敲擊樹木時，速度達6 -7 m/s，減速度更高達1000 g，但卻不會因此產生腦震盪等損傷。 經過文獻的彙整，我們認為大腦的質量效應為主要原因，啄木鳥的大腦約為人類的千分之一，因此抗加速度的能力估算可為人類的10倍。另外啄木鳥的腦脊髓液厚度特別的薄是另一個原因，經我們建立的大腦模型可發現啄木鳥的腦脊髓液厚度約0.1 mm時會有最好的減震能力，而人類的腦脊髓液厚度約為5 mm，與文獻符合。 另外我們建立了啄木鳥頭部的機械模型，在頻率響應的部分，從碰撞模擬中可發現混沌現象，為了在高頻下避免混沌現象的發生，因此脖子的剛性必須夠高。在隔震效果的部分，經模型的減震之後，在腦脊髓液厚度為0.1 mm的情況下，大腦相對於鳥喙的加速度減少至78%，若在腦脊髓液厚度為0.25 mm的情況下，大腦相對於鳥喙的加速度會增加至約150%，明顯看出腦脊髓液厚度的重要性。

In the history of technology, humans always get new ideas from nature. This concept is known as bionics. The reason why woodpeckers do not get head injuries at a high speed of 6-7 m/s with a deceleration of 1000g when drumming their heads against tree trunks is one of the most interesting research topics in the field of bionics. From extensive literature research, we believe there are two major reasons why woodpeckers do not get head injuries. The first reason is mass effect: the brain size of woodpeckers is about one thousandth the size of humans’. That means that woodpeckers can withstand ten times more acceleration than humans’. The second reason is that woodpeckers have a very narrow subarachnoid space, and therefore relatively little cerebrospinal fluid. By applying brain modeling, we discover that the woodpecker’s brain has the best ability of alleviating impact with about 0.1 mm thickness of subarachnoid space which differs from the thickness of subarachnoid space of humans, which is about 5 mm thick. Regarding the frequency behavior, we find chaos phenomenon during the simulation of impact with the mechanical model of the head of a woodpecker. In order to prevent chaos, the stiffness of neck has to be high enough. Regarding the effect of alleviating impact, the acceleration of the brain with respect to the beak will reduce to 78% with 0.1 mm thickness of subarachnoid space. However the acceleration of brain with respect to the beak will rise to 150% with 0.25 mm thickness of subarachnoid space. It verifies the importance of the thickness of subarachnoid space for alleviating impact.