• Thomas R. Hay, Ph.D., P.E

Acoustic Emission Testing of Steel Bridges

Introduction


Acoustic emission testing (AET) is a well-established non-destructive testing (NDT) technology commonly used to detect fatigue cracks in steel and composite pressure vessels, above ground atmospheric storage tanks, and steel and concrete bridges. Acoustic emission testing is characterized as a passive NDT technique since it does not insert some type of energy into the structure to interrogate for material anomalies. The structure must be stressed to a level that causes the fatigue crack to grow. As the fatigue crack grows in the micrometer range, or even less, acoustic emission is emitted from the fracturing material. Acoustic emission is simply a set of ultrasonic waves that that travel through material. AE makes it way to sensors mostly via longitudinal, shear, surface, and guided waves.