Engineering
The Corbin Bridge in Pennsylvania was the first to have an aluminum deck replacement (in 1996). Aluminum welds for such decks are being characterized by neutron scattering.
Because of its applications in engineering, neutron scattering has played an important role in protecting public safety and the environment. It has guided improvements to ensure that trains don't veer off tracks, wings don't fall off airplanes, and pipelines don't corrode enough to leak oil. When such failures do occur, they are often caused by internal stresses, which develop in a part during the manufacturing process and can predispose materials to cracking, wear, and failure caused by external stresses. Engineers want to know when a part is likely to fail and whether use of different materials or manufacturing processes would produce a more durable part. Neutron scattering results—combined with computer models—is providing these answers.
Neutron research is leading to more effectively and safely engineered materials, such as bridges, airplanes, and oil pipelines.
Neutron scattering capabilities allows engineers to measure subtle structural details in small samples or in huge engineering samples, such as earth-moving equipment. Such research enables effective measurements of residual stresses in composites—which are being increasingly used to make cutting tools, engine parts, and aircraft—because they are stronger and lighter than other materials.
Neutron scattering has been used to determine how to best manufacture and weld piping materials for use in oil pipelines to reduce residual stresses and prevent cracking and oil leaks.
Neutrons are also being used to study residual stresses in aluminum welds. The aluminum industry is interested in building aluminum bridge decks that are as strong and corrosion resistant as steel decks. Because aluminum decks are lighter than steel ones, less costly support structures can be built. Plus, the modular construction of aluminum decks makes it easy to replace parts.
Putting Your Car in a Quiet Gear
We all want our cars to run well and quietly. Whether they do depends in part on the precision and uniformity of the gears that transfer power from the engine to the wheels.
Manufacturing processes, however, can introduce distortions and residual stresses deep inside the gear material. These flaws—difficult to measure with conventional techniques—often cause poor performance or premature breakdowns, not to mention an annoying growl. Researchers can now use capabilities provided by HFIR and the Residual Stress User Center, which is part of the ORNL High Temperature Materials Laboratory, to determine residual stresses in automobile transmission gear.
Neutrons from the reactor can penetrate far into most engineering materials without damaging the material, allowing engineers to identify residual stresses without destroying the gear. Stresses can be mapped at points separated by only one millimeter.
These promising initial results led General Motors Corporation, Ford Motor Company, and other industrial members of the National Center for Manufacturing Sciences to ask that ORNL's Residual Stress User Center and Los Alamos National Laboratory join them in collaborative research. For automobile owners, the result of this collaboration could be a quiet ride that lasts for miles and miles.
