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UCLA Researchers Simulate Designer Materials for New Applications
Multiscale System Reduces Development Time and Costs
(From left): Qiyang Hu, Ming Wen, Mike Andersen, Zhiqiang (Frank) Wang, Professor Nasr Ghoniem,
Sam Liu, David Nguyen, and Adjunct Professor Shahram Sharafat. |
With advances in engineering and technology, researchers are now able to build new materials for very specific applications, enabling more fuel-efficient automobiles, stronger airplanes, and improved defense systems.
Despite the benefits, creating designer materials can be time-consuming and expensive. If researchers overlook a key function of a new material or miscalculate its properties, they must repeat the entire development and production process – oftentimes more than once.
That may soon change thanks to efforts led by Nasr Ghoniem, a mechanical and aerospace engineering professor at the UCLA Henry Samueli School of Engineering and Applied Science, whose large-scale computer simulations are based on nearly 100 years of scientists’ collected experience with materials.
In Ghoniem’s multiscale modeling system, a material’s features are simulated in a computer. Using a physically based approach for design and prediction of the new material’s performance allows the researchers to work with a virtual sample from the atomic scale on up.
“Our system uses advanced computer models accelerate the design of new materials for particular functions,” explains Ghoniem. “For instance, we helped develop a tungsten ‘foam’ material that can absorb thermal and mechanical energy ‘blasts’ for the defense and energy industries.”
Three-dimensional temperature distributions in flow
channels of a module designed for the International
Thermonuclear Tokamak Reactor to bebuilt in France.
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Using his large-scale computer network, researchers can apply external forces such as pressure and extreme temperatures to design and test the new material before it’s ever manufactured. After the simulated material exhibits all of the desired properties, engineers can work with a manufacturer to move it into the real world.
At the request of the Air Force, Ghoniem’s group has designed ultra strong materials for aerospace and aeronautics. By layering nickel and copper at the nanoscale level, they created a new material that is 10 times lighter and 1,000 times stronger than naturally occurring materials. Each layer is only 10 to 20 nanometers thick – much thinner than a single human hair.
“The more theory and experimental data we need to apply to the simulations, the more useful the system will be,” says Ghoniem. “Using existing data, we’re examining the correlations between materials, and then testing new theories through simulations.”
The simulation researchers have discovered that successful creation of new materials requires knowledge from multiple fields. This new area of research integrates materials science, physics, chemistry, and many more disciplines while addressing needs for a wide range of applications.
Among these, the team is designing a highly reflective material for large-area mirrors deployed in space for energy extraction and defense applications. The new material would be able to withstand repeated interactions with lasers without becoming flawed and unusable, unlike the mirrors currently deployed.
Multiscale modeling systems like the one at UCLA enable researchers to simulate the behavior of materials at all length and time scales. Using quantum mechanics and molecular dynamics, they predict the movement of atoms and their interactions, up to one billion atoms at a time.
The formation of equiaxed and elongated cells made up of dislocation patterns. The microstructure controls the fatigue resistance of copper, but the reasons for pattern formation is unknown. Computer simulations in Professor Ghoniem's laboratory are working toward unraveling pattern formation mysteries. |
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“Scaled modeling is necessary because materials vary from section to section,” notes Ghoniem. “Just as you would get a range of features from sampling a mountain – sand, trees, rocks, and other structures – so materials vary at the atomic level. Within a solid we have atoms, electrons, solid crystal grains, cracks, dislocations, heterogeneities, etc.”
The team’s simulations run on the UCLA-ISIS cluster of 90 AMD machines, each with two processors connected in parallel, which gives them the power of 180 computers. For larger simulations, the group uses a “divide and conquer” approach, dividing the project into smaller pieces for the computers to work on individually under the direction of a maestro computer, which directs and assembles their work.
“We’re working on a wide range of projects,” says Ghoniem, “but in every case we’re looking at the material at its basic level. Through multiscale modeling techniques, we’re gaining a much better understanding of the materials’ basic properties, which means that we’re more likely to develop a broad set of applications for each.”
For more information on multiscale modeling of materials, please visit http://osiris.seas.ucla.edu/ or contact Professor Ghoniem at ghoniem@seas.ucla.edu.
-Marlys Amundson
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