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:6/27/2016)... , June 27, 2016 Research and Markets ... America 2016-2020" report to their offering. ... North America to grow at a CAGR of 12.28% ... prepared based on an in-depth market analysis with inputs from industry ... over the coming years. The report also includes a discussion of ...
(Date:6/22/2016)... American College of Medical Genetics and Genomics was once again ... of the fastest-growing trade shows during the Fastest 50 Awards ... Las Vegas . Winners are ... of the following categories: net square feet of paid exhibit ... 2015 ACMG Annual Meeting was ranked 23 out of 50 ...
(Date:6/22/2016)... , June 22, 2016   ... management and verification solutions, has partnered with ... software solutions for Visitor Management, Self-Service Kiosks ... provides products that add functional enhancements to ... provides corporations and venues with an automated ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... , June 27, 2016  Alex,s Lemonade Stand ... that that it will open a state-of-the-art bioinformatics lab, ... cancer research. This announcement comes as Liz Scott ... the National Cancer Moonshot Summit in Washington, ... Biden as a participant and advocate of pediatric cancer ...
(Date:6/27/2016)... , June 27, 2016  Global demand for ... percent through 2020 to $7.2 billion.  This market ... beverages, cleaning products, biofuel production, animal feed, and ... diagnostics, and biocatalysts). Food and beverages will remain ... by increasing consumption of products containing enzymes in ...
(Date:6/27/2016)... /PRNewswire/ - BIOREM Inc. (TSX-V: BRM) ("Biorem" or "the Company") ... shareholders, Clean Technology Fund I, LP and Clean Technology ... based venture capital funds which together hold approximately 59% ... diluted, as converted basis), that they have entered into ... holdings in Biorem to TUS Holdings Co. Ltd. ("TUS") ...
(Date:6/27/2016)... -- Sequenom, Inc. (NASDAQ: SQNM ), a life ... development of innovative products and services, announced today that ... denied its petition to review decisions by ... Patent No. 6,258,540 (",540 Patent") are not patent eligible ... Court,s Mayo Collaborative Services v. Prometheus Laboratories decision.  In ...
Breaking Biology Technology: