Navigation Links
Reinventing the wheel -- naturally
Date:6/14/2010

Humans did not invent the wheel. Nature did.

While the evolution from the Neolithic solid stone wheel with a single hole for an axle to the sleek wheels of today's racing bikes can be seen as the result of human ingenuity, it also represents how animals, including humans, have come to move more efficiently and quicker over millions of years on Earth, according to a Duke University engineer.

Adrian Bejan, professor of mechanical engineering at Duke's Pratt School of Engineering, argues that just as the design of wheels became lighter with fewer spokes over time, and better at distributing the stresses of hitting the ground, animals have evolved as well to move better on Earth. In essence, over millions of years, animals such as humans developed the fewest "spokes," or legs, as the most efficient method for carrying an increasing body weight and height more easily.

"This prediction of how wheels should emerge in time is confirmed by the evolution of wheel technology," Bejan said. "For example, during the development of the carriage, solid disks were slowly replaced by wheels with tens of spokes."

The advantage of spokes is that they distribute stresses uniformly while being lighter and stronger than a solid wheel. "In contrast with the spoke, the solid wheel of antiquity was stressed unevenly, with a high concentration of stresses near the contact with the ground, and zero stresses on the upper side," Bejan said. "The wheel was large and heavy, and most of its volume did not support the load that the vehicle posed on the axle.

"If you view animal movement as a 'rolling' body, two legs, swinging back and forth, perform the same function of an entire wheel-rim assembly," Bejan said. "They also do it most efficiently like one wheel with two spokes with the stresses flowing unobstructed and uniformly through each spoke. The animal body is both wheel and vehicle for horizontal movement."

Bejan's analysis was published early online in the American Journal of Physics. His research is supported by the National Science Foundation and the Air Force Office of Scientific Research.

"An animal leg is shaped like a column because it facilitates the flow of stresses between two points like the foot and hip joint, or paw and shoulder," Bejan said. "In the example of the Neolithic stone wheel, the flow of stresses is between the ground and the whole wheel."

Bejan believes that the constructal theory of design in nature (www.constructal.org), which he started describing in 1996, predicts these changes in the wheel and animal movement. The theory states that for a design (an animal, a river basin) to persist in time, it must evolve to move more freely through its environment.

Since animal locomotion is basically a falling-forward process, Bejan argues that an increase in height predicts an increase in speed. For a centipede, each leg represents a point of contact with ground, which limits the upward movement of the animal. As animals have fewer contacts with ground, they can rise up higher with each stride.

"The constructal theory shows us this forward-falling movement is dictated by the natural wheel phenomenon, which is required for the minimal amount of effort expended for a certain distance traveled," Bejan said.

An earlier analysis by Bejan showed that larger human swimmers are faster because the wave they create while swimming is larger and thus carries them forward faster.

While wheel-like movement evolved naturally, it also describes what Bejan likes to call "nature's gear box." Humans have two basic speeds, Bejan said walking and running. A running human gets taller, or higher off the ground, with each stride, which increases his speed.

A horse has three speeds walk, trot and gallop.

"The horse increases its speed by increasing the height from which it falls during each cycle," Bejan said. "Then, from the trot to the gallop, the body movement changes abruptly such that the height of jump increases stepwise for each stride. Nature developed not only wheel-like movement but also mechanisms for changing speeds."


'/>"/>

Contact: Richard Merritt
richard.merritt@duke.edu
919-660-8414
Duke University
Source:Eurekalert  

Related biology news :

1. Reinventing technology assessment for the 21st century
2. Saving energy and the environment with Flywheels
3. Clinical trial shows quadriplegics can operate powered wheelchair with tongue drive system
4. Medicine wheel model for nutrition shows promise for control of type 2 diabetes
5. Naturally-occurring apple compounds reduce risk of pancreatic cancer
6. Self-moisturizing contact lenses, naturally
7. Rabbits on the back foot -- but naturally theyre fighting back
8. Study shows pine bark naturally relieves symptoms of acute hemorrhoids
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Reinventing the wheel -- naturally
(Date:4/5/2017)... April 5, 2017  The Allen Institute for Cell ... Explorer: a one-of-a-kind portal and dynamic digital window into ... data, the first application of deep learning to create ... cell lines and a growing suite of powerful tools. ... these and future publicly available resources created and shared ...
(Date:4/4/2017)... April 4, 2017   EyeLock LLC , a ... the United States Patent and Trademark Office (USPTO) has ... the linking of an iris image with a face ... represents the company,s 45 th issued patent. ... very timely given the multi-modal biometric capabilities that have ...
(Date:3/30/2017)... The research team of The Hong Kong Polytechnic University (PolyU) ... ground breaking 3D fingerprint minutiae recovery and matching technology, pushing contactless ... use in identification, crime investigation, immigration control, security of access and ... ... A research team led by Dr Ajay Kumar ...
Breaking Biology News(10 mins):
(Date:5/23/2017)... ... May 23, 2017 , ... A recent survey conducted by the Weed ... to control weed in 12 categories of broadleaf crops, fruits and vegetables, while common ... the U.S. and Canada participated in the 2016 survey, the second conducted by WSSA. ...
(Date:5/23/2017)... ... May 22, 2017 , ... ... a row in the Aragon Research Globe™ for Corporate Learning, 2017. , Aragon ... direction and market demand, and effectively perform against those strategies. NetDimensions’ ranking as ...
(Date:5/23/2017)... ... May 23, 2017 , ... ... applications, has announced a facility expansion to accommodate its rapid growth. , The ... new workspace and renovation of the existing areas. The expansion includes, a state-of-the-art ...
(Date:5/23/2017)... ... May 23, 2017 , ... Cambridge Semantics , the leading ... year’s Bio-IT World Conference and Expo in Boston May 23-25 with a ... The Anzo Smart Data Lake is also a finalist for the Best of ...
Breaking Biology Technology: