Even the strongest material has its breaking point. Conventional metal-fatigue tests can take hours and rely on computer-controlled hydraulic machines that cost up to $100,000. But engineers Eric Stromswold and David Quesnel at the University of Rochester have devised a simple, inexpensive test for metals such as steel and aluminum that are used in airplanes or spacecraft, where low weight and high strength are a top priority.
The process measures how well a material can resist fracturing once a crack develops. Small metal samples are placed in a vise between two wrench heads. The vise twists the metal sharply to develop a crack, then measures the increasing force required to snap the sample completely.
The testing equipment will cost less than $1,000 and will measure fracture-resistance in a few minutes. It isn't intended for more sophisticated metallurgical analysis--such as determining exactly how a fracture develops. Instead, Stromswold says, the researchers expect the "toughness tool" to be useful in the quality-control market, where large numbers of samples must be tested quickly.