Numbers Made Real

By Matt Smith

A Perfect Weld

Creating a New Construct

In 1973, during China's Cultural Revolution, Pingsha Dong, originally from Dalian, was transplanted for re-education into the hinterland, where the schools reduced the curriculum to communist rote. Before he left, his father told him that no matter what the risk, "you need to learn." So, after 16 hours in the field each day, Dong stole away at night with a kerosene lamp to pore over two math and physics books his father had salvaged for him. Eventually the authorities caught on to Dong's reading, but since he disguised his books to resemble Mao's Little Red Book, they praised his party fervor. That reputation gave him the rare chance to attend college, leave the fields and then leave China. "If you go through that," he says, "nothing else is difficult." Well, almost nothing. Dong was introduced to welding as a student at Harbin Institute of Technology in China much against his will. "It was a nightmare," he recalls. Now, as a researcher at Battelle Institute in Columbus, Ohio, he's revolutionizing the field. The current methods for determining the life span, or what engineers call fatigue life, of a welded joint are notoriously imprecise. Dong refused to resign himself to the same guesswork that other engineers have long thought unavoidable. A man who has to keep himself from thinking after 9 p.m. in order to prevent insomnia, he had his eureka moment while reading himself to sleep five years ago. On a magazine ad covered in his scribblings, Dong's method, dubbed Verity, was born. Engineers had been calculating fatigue life the wrong way for 60 years. Push your hand against a tabletop. Force is the amount of effort you exert; stress is how that force is distributed across your palm. Push your hand against a corner, and the stress becomes impossible to compute reliably. But if you can figure out how much effort you're using (force), stress becomes much easier to calculate. That's Verity's key. The result: with unprecedented precision, engineers can predict how long a welded joint will last. Meaning? Car companies like Ford spend years and millions of dollars testing welds. Dong says Verity makes 90% of that redundant. --By Matt Smith