Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

From the bone of a horse, a new idea for aircraft structures

03.12.2002


The horse, a classic model of grace and speed on land, is now an unlikely source of inspiration for more efficient flight.



So says a group of University of Florida engineers who have recreated part of a unique bone in the horse’s leg with an eye toward lighter, stronger materials for planes and spacecraft.

The third metacarpus bone in the horse’s leg supports much of the force conveyed as the animal moves. One side of the cucumber-sized bone has a pea-sized hole where blood vessels enter the bone. Holes naturally weaken structures, causing them to break more easily than solid structures when pressure is applied. Yet while the third metacarpus does fracture, particularly in racehorses, it doesn’t break near the hole - not even when the bone is subjected to laboratory stress tests.


UF engineering researchers think they’ve figured out why - and they’ve built and are testing a plate that mimics the bone’s uncanny strength in a form potentially useful for airplanes and spacecraft.

"Holes are a classic source of failure in engineered structures, but nature has found a way around that in this bone," said Andrew Rapoff, an assistant professor of aerospace and mechanical engineering and the lead researcher on the project. "We’re mimicking nature’s solution."

The researchers have published at least five papers on their work, which they’ve been conducting for three years with the assistance of a $675,000 NASA grant. Most recently, they were invited to submit a paper to a special issue of the Journal of Biomechanics to appear next year.

Airplanes have holes for wiring, fuel and hydraulic lines. Similar holes are common in boats, buildings, automobiles, homes and virtually any other structure that has functions beyond simply sheltering or containing something. Engineers typically compensate for the weaknesses caused by these holes by increasing the thickness of the material around them. In a classic example, ship builders add extra material around portholes in hulls to guard against structural weakness or failure, said Stephen Cowin, a distinguished professor of mechanical engineering and director of the New York Center for Biomedical Engineering at The City College of New York.

The shortcoming of that approach is that it adds weight, a problem for airplanes and spacecraft that need to be as light as possible, Rapoff said. The rule of thumb in the aerospace industry is that reducing the weight of a plane by one pound saves 10 pounds of fuel, so techniques to maintain aircraft strength without adding weight are sorely needed. This is true particularly for spacecraft that have extremely high launch costs, he said.

The engineers analyzed the structure of the horse bone around its hole - or foramen - with microscopy and microradiography, techniques that render the details of its microscopic composition. They converted the resulting information into equations describing the bone’s mechanical properties - for example, converting the bone’s mineral density and porosity into an equation describing its stiffness. The engineers then developed a computer model that mimics the bone’s behavior under stress, proving the model’s accuracy by testing it against laboratory tests of the bone.

The upshot of their analyses: The bone was configured in such a way that it pushed the highest stresses away from the foramen into a region of higher strength. For example, the position of its osteons, or structural units created when the bone first developed, routed stress around the foramen.

The engineers used their analyses and computer model to create a "biomimetic plate," with a hole surrounded by several different grades of polyurethane foam to mimic the compositional structure of the bone near the foramen. Biomimetics describes the increasingly common engineering trend of mimicking natural solutions in manmade materials.

The researchers tested the plate by placing it across two upright pillars and weighing it down, comparing the results with those from an identical test of a plate with a drilled hole without the foam stabilizer. It took twice the weight to break the biomimetic plate. Moreover, when it did finally break, the fracture did not go through the hole as occurred with the plate with the drilled hole.

UF master’s student Barbara Garita has recently taken the work a step further. Garita, one of several master’s and doctoral students working on the project, has demonstrated the foramen in the natural bone is stronger than a drilled hole when thin sections of the bone are subjected to repeated stress over time. The engineering researchers plan to subject the biomimetic plate to similar cyclical stress conditions that are common in real life, occurring, for example, when a boat pounds waves or an airplane experiences repeated turbulence. "We’ll solve many problems using this bone," Garita said.

Rapoff and Cowin said applications for the research will grow as manufacturing techniques to create products composed of different grades of material improve.

"We’ll be able to manufacture materials with modern machinery in a very elegant way that allows us to vary the properties the way that nature does," Cowin said, adding that the University of Florida researchers are the only researchers he’s aware of who are examining the problem using a biomimetic approach.

Basic versions of so-called "functionally graded materials" already are used in airplanes and spacecraft, for example, in wing flaps made from material arranged in a honeycomb pattern overlaid with metal, Rapoff said. Future versions will replace the honeycomb pattern with continuous gradations of differently composed materials. If the flap or other elements of the structure built with such materials need holes, it would make sense to draw on the UF research on the horse bone foramen, he said.

"We’ve told the world ’this is how you design near holes for minimum weight and maximum strength,’" he said. "Now it’s up to the designers and manufacturers to make these sorts of things."


###
Writer: Aaron Hoover
ahoover@ufl.edu 352-392-5523

Source: Andrew Rapoff
rapoff@ufl.edu

Andrew Rapoff | EurekAlert!
Further information:
http://www.ufl.edu/

More articles from Process Engineering:

nachricht Quick, Precise, but not Cold
17.05.2017 | Fraunhofer-Institut für Lasertechnik ILT

nachricht A laser for divers
03.05.2017 | Laser Zentrum Hannover e.V.

All articles from Process Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

Ultrathin device harvests electricity from human motion

24.07.2017 | Power and Electrical Engineering

Scientists announce the quest for high-index materials

24.07.2017 | Materials Sciences

ADIR Project: Lasers Recover Valuable Materials

24.07.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>