Designing structures and devices that protect the body from shock and vibrations during high-velocity impacts is a universal challenge.
Scientists and engineers focusing on this challenge might make advances by studying the unique morphology of the woodpecker, whose body functions as an excellent anti-shock structure.
This is a schematic of the pecking process of a woodpecker and the Mises stress at different times: (a) and (e) are moments of readiness to peck; (b) and (d) are the moments of departure and return, respectively; (c) is the moment of collision; arrows on the beaks show velocity direction.
Credit: ©Science China Press
The woodpecker's brain can withstand repeated collisions and deceleration of 1200 g during rapid pecking. This anti-shock feature relates to the woodpecker's unique morphology and ability to absorb impact energy.
Using computed tomography and the construction of high-precision three-dimensional models of the woodpecker, Chinese scientists explain its anti-shock biomechanical structure in terms of energy distribution and conversion.
Their findings, presented in a new study titled "Energy conversion in the woodpecker on successive pecking and its role in anti-shock protection of the brain" and published in the Beijing-based journal SCIENCE CHINA Technological Sciences, could provide guidance in the design of anti-shock devices and structures for humans.
To build a sophisticated 3D model of the woodpecker, scientist Wu Chengwei and colleagues at the State Key Lab of Structural Analysis for Industrial Equipment, part of the Department of Engineering Mechanics at the Dalian University of Technology in northeastern China, scanned the structure of the woodpecker and replicated it in remarkable detail.
"CT scanning technology can be used to obtain the images of internal structures of objects … which is widely used in the medical field and expanded to mechanical modeling of biological tissue," they explain in the study.
"Based on the CT scanning technology (CT scanner, LightSpeed VCT XT, GE, USA), detailed inner structure images of the head were obtained and then imported to Mimics software to form a scattered-points model," they state. "Then a geometric model of the head was set up using the facet feature and remodeling module of Pro/E for the surface fitting. After the geometric repairs, the FE [finite element] model meshed by tetrahedron elements was established using Abaqus software."
The woodpecker's structure was recreated through intricate geometric modeling. "The final FE model has 940000 fine elements with a minimum size of 0.07 mm in the head, 70000 coarse elements with a maximum size of 3.5 mm in the body and 20000 elements with a minimum size of 0.16 mm in the trunk," the researchers state.
Discoveries made during the study could have applications in the design of spacecraft, automobiles, and wearable protective gear, explains Professor Wu.
"High-speed impacts and collisions can destroy structures and materials," Wu states. "In the aerospace industry, spacecraft face the constant danger of collisions with space debris and micrometeoroids," Wu adds. "If a spacecraft's structure or scientific instruments were destroyed by impact, the economic loss would be huge."
In cities worldwide, Wu says, automobile accidents are a persistent threat to human safety, and head injuries are common.
Challenges presented in minimizing these threats and injuries have led to widespread efforts to understand and replicate or improve on anti-shock mechanisms found in nature.
The woodpecker stands out in this field of study: it can peck trees at high frequency (up to 25 Hz) and high speed (up to 7 m/s and 1200 g deceleration) without suffering any brain injury.
"This unique anti-shock ability inspires scientists to uncover the related bio-mechanisms," Wu states, for potential engineering of similar devices and structures based on principles of biomimicry.
Wu and colleagues used 3D models of the woodpecker to test how impact energy was handled by its specially adapted structure.
Figure 1 shows the pecking process of a woodpecker and the Mises stress at different times.
The results showed that the body not only supports the woodpecker to peck on the tree, but also stores the majority of the impact energy in the form of strain energy, significantly reducing the quantity of impact energy that enters the brain.
"Most of the impact energy in the pecking is converted into the strain energy stored in the body (99.7%) and there is only a small fraction of it in the head (0.3%)," the researchers reported.
Structures in the head including the beak, skull, and hyoid bone further reduce the strain energy of the brain. The small fraction of impact energy that enters the brain will be eventually dissipated in form of heat, causing a rapid temperature increment in the brain. As a consequence of this, the woodpecker has to peck intermittently.
This research project received funding in the form of grants from the National Science Foundation of China (Grant No. 11272080), the Doctoral Education Foundation of China Education Ministry (Grant No. 20110041110021), and the Fundamental Research Funds for the Central Universities of China (Grant No. DUT14LK36).
See the article: Zhu Zhaodan, Zhang Wei and Wu Chengwei. "Energy conversion in the woodpecker on successive peckings and its role on anti-shock protection of the brain."
SCIENCE CHINA Technological Science. 2014, 57(7): 1269-1275. http://link.springer.com/article/10.1007%2Fs11431-014-5582-5
SCIENCE CHINA Technological Science is produced by Science China Press, a leading publisher of scientific journals in China that operates under the auspices of the Chinese Academy of Sciences. Science China Press presents to the world leading-edge advancements made by Chinese scientists across a spectrum of fields. http://www.scichina.com/english/
Wu Chengwei | Eurek Alert!
New study first to predict which oil and gas wells are leaking methane
21.12.2018 | University of Vermont
Droughts boost emissions as hydropower dries up
21.12.2018 | Stanford's School of Earth, Energy & Environmental Sciences
The scientific and political community alike stress the importance of German Antarctic research
Joint Press Release from the BMBF and AWI
The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...
World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles
The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.
Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.
In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...
Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.
It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:
The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.
One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
21.01.2019 | Life Sciences
21.01.2019 | Physics and Astronomy
21.01.2019 | Life Sciences