Understanding Acoustic Emission Testing- Reading 1 Part B-A

Measurements of the effects of attenuation on an AE signal can be performed
with a simple apparatus known as a Hsu-Nielson Source. This consists of a
mechanical pencil with either 0.3 or 0.5 mm 2H lead that is passed through a
cone-shaped Teflon shoe designed to place the lead in contact with the
surface of a material at a 30 degree angle. When the pencil lead is pressed
and broken against the material, it creates a small, local deformation that is
relieved in the form of a stress wave, similar to the type of AE signal produced
by a crack. By using this method, simulated AE sources can be created at
various sites on a structure to determine the optimal position for the
placement of sensors and to ensure that all areas of interest are within the
detection range of the sensor or sensors.
Charlie Chong/ Fion Zhang