ISU Research Center Receives Gift to Improve Railway Inspection

AMES, Iowa - Iowa State University's Center for Nondestructive Evaluation has received a gift of equipment and financial support from the Krautkramer Branson company, a producer of phased-array ultrasound equipment headquartered in Germany.

Valued at $50,000, the equipment, including a computer and an ultrasonic array probe, will enable CNDE associate scientist Dave Utrata to expand techniques for detecting and characterizing flaws in railroad rails. ISU was one of several schools to enter the company's equipment competition and received the award for proposing the most relevant and practical industrial application. An additional $16,000 to support research and related costs of using the equipment was also received.

CNDE's proposal to use the equipment on railroad rails is practical because rails are vulnerable to wear and damage after long periods of use and heavy loads. A well-trafficked stretch of rail carrying heavy loads can suffer from internal fatigue cracking. These flaws in steel rails, if not detected, can lead to derailment and catastrophic accidents. In addition to safety, rail inspection offers economic benefits by making it possible to identify flawed areas, cut them out and replace them, rather than replacing miles of rail.

The railroad industry inspects rail with ultrasonic techniques, where pulses of sound energy are sent into a material and echo back, producing an image of the internal flaws. However, current techniques may not catch all flaws. "The tools used to inspect rails do a good job, but they could possibly be made more efficient and comprehensive using this new phased-array technology," Utrata said.

Today, rail inspections are performed with a fluid-filled wheel suspended under a high-railer inspection vehicle. Inside the wheel are fixed transducers that pulse ultrasonic waves. A computer on the truck controls these pulses. Jets of liquid are sprayed along the track to conduct waves through the rail, which are directed at specific areas where cracks are most likely to be found. When the waves bounce back indicating a flaw has been detected, the computer records this data.

The benefits of the phased-array system include the ability to steer the ultrasonic probe, rather than using beams that target fixed places. "Conventional fixed probes don't offer the same range of positions for studying rail. The new phased-array system could give us beams of ultrasound that sweep through the rail, providing a new perspective on flaws in a more sensitive and efficient manner," Utrata said.

Utrata thinks that phased-array technology could eventually be combined with current techniques, directing multiple beams from a fluid-filled wheel or a sled device that would move along the tracks.

After conducting three months of research comparing phased-array technology to the fluid-filled wheel method on rail samples, Krautkramer Branson's gift will become part of the arsenal of tools in the Iowa Demonstration Laboratory for Nondestructive Evaluation Applications, Utrata said. "We currently have one of each commercial phased-array inspection system here at CNDE. We can add these new pieces to our toolbox and use them for other engineering materials, including other metals and plastics," he said.

IDL is an outreach program of the Center for Nondestructive Evaluation at Iowa State University. A fully equipped nondestructive evaluation facility, it has capabilities in the six most commonly used NDE methods and can provide up to 40 hours of research and testing support to Iowa companies at no cost.

"While we don't have any rail manufacturers in Iowa, we certainly have miles and miles of rail, and manufacturers of other engineering materials could benefit from demonstration of the new phased-array system," Utrata said. "Phased-array technology offers potential for better inspection methods that could be used anywhere."

The Center for Nondestructive Evaluation is a member of the Institute for Physical Research and Technology, a network of research and technology-transfer centers and industrial-outreach programs at Iowa State University.

Last updated September 6, 2006 rbm