The five most common NDT methods are Penetrant, X-ray, Ultrasonics, Eddy current and Magnetic Particle Inspection.  For crack detection all of these methods rely on the crack interacting with the applied fluids/radiation/magnetic field etc, and this interaction is often influenced by the tightness with which the individual crack surfaces are held together.  The techniques are generally more sensitive to open cracks than closed ones. The Thermosonics project above detects cracks using the heat generated by the crack surfaces rubbing during low frequency vibration; it is also known that vibro-modulation can enhance ultrasonic detection of closed cracks (see project above).  This project will investigate whether similar improvements can be made to penetrant inspection by applying a vibration field and will quantify the benefits of all the vibro modulation methods.

Example of vibro enhancement of standard NDT methods