Subscribe free to our newsletters via your
. 24/7 Space News .




CAR TECH
Reinventing The Wheel Naturally
by Staff Writers
Durham NC (SPX) Jun 15, 2010


"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. This is a fanciful rendering of Leonardo da Vinci's Vetruvian Man as a wheel. Credit: Adrian Bejan

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."

.


Related Links
Duke University
Car Technology at SpaceMart.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








CAR TECH
Honda says ops partially resume at troubled China plant
Beijing (AFP) June 14, 2010
Operations at a Honda parts factory in southern China partially resumed on Monday after nearly a week of disruption over a pay dispute, but some workers still refused to return, the company said. The Honda Lock factory in the southern province of Guangdong is one of a string of factories in China - and the third in the Honda family - hit by a wave of industrial unrest in the so-called "wor ... read more


CAR TECH
Water Content Of Moon's Interior Underestimated

Model Helps Search For Moon Dust Fountains

NASA Langley to Break Ground on Hydro Impact Basin

The Earth And Moon Formed Later Than Previously Thought

CAR TECH
NASA Dryden Hosts Radar Tests For Next Mars Landing

Spirit Remains Silent At Troy

Ancient Ocean May Have Covered One-Third Of Mars

A third of Mars once covered by ocean: study

CAR TECH
Japan's 'space yacht' starts sailing

Elbit Systems To Unveil EoShiel

Continued Development On 18 Small Business Tech Transfer Projects

ESA Astronauts At ILA In Berlin

CAR TECH
China Sends Research Satellite Into Space

China eyes Argentina for space antenna

Seven More For Shenzhou

China Signs Up First Female Astronauts

CAR TECH
Three New Crew Members En Route To ISS

Russian, US astronauts blast off to ISS: television

Rocket in place for space station mission

ISS Crew Does Maintenance And Science As Soyuz Launch Date Approaches

CAR TECH
Successful Launch Of Swedish Prisma satellites

South Korea Delays Rocket Launch

SpaceX Achieves Orbital Bullseye With Inaugural Flight Of Falcon 9 Rocket

Pratt and Whitney Rocketdyne Celebrates 50 Years

CAR TECH
Kepler Data On Potential Extrasolar Planets Released

CoRoT Unveils A Rich Assortment Of New Exoplanets

Exoplanet Caught On The Move

'Out Of Whack' Planetary System

CAR TECH
Flotilla Of NRL Space Sensors Study Upper Atmosphere

RIM making new touchscreen smartphone, tablet device: WSJ

Nintendo unveils 3-D handheld DS videogame device

"Kinect" motion control for Xbox 360 makes magical debut




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement