When you take a plane trip, drive across a bridge, or ride the commuter train to work, you trust that those structures and systems are safe. Likewise, pilots flying combat missions depend on their planes, and astronauts hurtling into space depend on the rockets propelling them.
Sankaran Mahadevan, the John R. Murray Sr. Chair in Engineering, works on ways to increase reliability and decrease risks of those and other complex structures and systems. His research regarding railroad wheels, spacecraft, dams, bridges, and even nuclear waste dumps has the potential to save human lives and millions of dollars.
Mahadevan and his colleagues in the Structural Reliability Research Group are developing computer models that can predict with a high degree of confidence whether a system will fail, when failure is likely to occur, and how to prevent such failure.
“Skyscrapers and bridges can’t be put through full-scale testing as can small mechanical and electrical devices,” says Mahadevan, who is a professor of civil, environmental and mechanical engineering. “You can’t test the reliability of large systems like space shuttles and warplanes by waiting to see what fails. No matter what the system, we have to be concerned about how reliable it is.”
Mahadevan also directs Vanderbilt’s Reliability and Risk Engineering and Management doctoral program, the largest and most prestigious of its kind in the world.
Today the program is self-sustaining, with governmental and private partners that include the Transportation Technology Center, Sandia National Laboratories, Federal Aviation Administration, NASA, U.S. Air Force, U.S. Department of Energy, Boeing Co., Bell Helicopter Textron and Union Pacific Corp.
Mahadevan is currently applying his expertise to NASA spacecraft. His team is working on calculating risk and uncertainty in such large systems by incorporating multiple disciplines like structures, aerodynamics, propulsion, mass and geometry into the computer programs. An acceptable risk for spacecraft is typically about one in 10,000.
“The question then becomes, ‘How good are our models?’” Mahadevan says, noting that many assumptions and very little data exist on which to base such predictions.
Mahadevan’s reliability methods can be used in the design, manufacture, operation and maintenance of equipment and systems in many fields. His research for the Federal Highway Administration, for example, identified which 2,000 bridges throughout the country should carry advanced structural health monitoring instrumentation. The team also developed a cost-effective way to inspect train wheels that demonstrated a 400 percent return on investment for partner Union Pacific.
Current research includes a U.S. Air Force Research Laboratory project to develop rapid systems health diagnosis and prognosis for warplanes. The group also is working on applying risk and reliability management to large complex systems like homeland security and transportation. Through a consortium of universities known as the CRESP project, the U.S. Department of Energy funds an effort to model the durability and uncertainty of concrete storage facilities for low-level nuclear waste. The team also has received a five-year, $1.2 million award from the FAA to develop advanced methods to predict fatigue and fracture—and their related uncertainty—in helicopter rotor components.