Other Reports

Tread Crack Detection in Railroad Wheels: An Ultrasonic System Using EMATS

  • 01
  • May
  • 1991
AUTHOR: R. E. Schramm, A. V. Clark, Jr., D. V. Mitrakovic
REPORT NUMBER: Report No. 22
SUBJECT: Facilities & Test Equipment
KEYWORDS: nondestructive testing, roll-by inspection
ABSTRACT: This is report number 22 in a series .covering research performed by the National Institute of Standards and Technology (NIST) for the Federal Railroad Administration (FRA). This report covers a project by the Materials Reliability Division (formerly the Fracture and Deformation Division) to develop and build an ultrasonic system to detect crack-type flaws in the tread of railroad wheels. To achieve fully automatic operation, the sensor is built into the rail so testing occurs as the train rolls past. Signal analysis takes place in real time. The ultrasonic probe is an EMAT (electromagnetic-acoustic transducer). As configured here, the EMAT has a small footprint, and, due to its principle of operation, it does not require any acoustic couplant. The system operates in a pitch-catch mode. A short burst of Rayleigh (surface) waves travels around the wheel tread, and an echo indicates a flaw's presence and size. Testing was performed on both a short track in the NIST laboratory and the full-scale facilities of the Transportation Test Center (TTC) in Pueblo, Colorado. This report documents the design, construction, and testing of the system. It is also to serve as an operational guide for the equipment being delivered to the FRA.