Ultrasonic Inspection is one of the NDT methods to find out the condition of elastic materials (metals and few non - metals) by means of injecting mechanical vibrations into the materials the resulting change is detected by the testing system , and through an indication , we learn about the specimen.
Our job is to apply the system to the specimen and interpret the result through the indication
This method is capable of detecting surface, subsurface and internal discontinuities on materials.
The theory of ultrasonic propagation is exactly the same as that of audible sound.
The ultrasonic method is used on processed materials, finished components and for in-service inspection on parts and assemblies.
Ultrasonic waves can penetrate through several meters in to the material. The waves can be propagated through liquids, solids and gases.
Visualize that we have testing system and something called ultrasonic vibration we apply to the specimen no recognizable response can be obtained from the testing system. Since no recognizable response was obtained , we do not know anything about the specimen. That means the specimen does not adapt to ultrasonic testing.
To learn something about the specimen , we need a response or reaction that we can interpret.
Therefore , we cant learn anything about the specimen. Another form of NDT method should be used in this case.
