Ultrasonic testing

Ultrasonic testing is often performed on steel and other metals and alloys, though it can also be used on concrete, wood and composites, albeit with less resolution.

It is used in many industries including steel and aluminium construction, metallurgy, manufacturing, aerospace, automotive and other transportation sectors.

[1] On May 27, 1940, U.S. researcher Dr. Floyd Firestone of the University of Michigan applies for a U.S. invention patent for the first practical ultrasonic testing method.

The echo pulses that are reflected are received by the same or by a different transducer and are converted into electrical signals which indicate the presence of the defect.” To characterize microstructural features in the early stages of fatigue or creep damage, more advanced nonlinear ultrasonic tests should be employed.

These nonlinear methods are based on the fact that an intensive ultrasonic wave is getting distorted as it faces micro damages in the material.

Using the couplant increases the efficiency of the process by reducing the losses in the ultrasonic wave energy due to separation between the surfaces.

Measurement of grain size using ultrasound can be accomplished through evaluating ultrasonic velocities, attenunations, and backscatter feature.

[6] This concepts of ultrasonic proving can be used to inversely resolve the grain size in the time domain when the scattering attenuation coefficient is measured from testing data, providing the non-destructive way to predict material's property with rather simple instruments.

An example of Ultrasonic Testing (UT) on blade roots of a V2500 IAE aircraft engine .
Step 1 : The UT probe is placed on the root of the blades to be inspected with the help of a special borescope tool (video probe).
Step 2 : Instrument settings are input.
Step 3 : The probe is scanned over the blade root. In this case, an indication (peak in the data) through the red line (or gate) indicates a good blade; an indication to the left of that range indicates a crack.
Principle of ultrasonic testing. LEFT: A probe sends a sound wave into a test material. There are two indications, one from the initial pulse of the probe, and the second due to the back wall echo. RIGHT: A defect creates the third indication and simultaneously reduces the amplitude of the back wall indication. The depth of the defect is determined by the ratio D / E p
At a construction site, a technician tests a pipeline weld for defects using an ultrasonic phased array instrument. The scanner, which consists of a frame with magnetic wheels, holds the probe in contact with the pipe by a spring. The wet area is the ultrasonic couplant that allows the sound to pass into the pipe wall.
Non-destructive testing of a swing shaft showing spline cracking