Ultra sonic technique for hidden corrosion detection in air craft wing skin
Different causes of corrosion includes moisture, water and cracks which easily affects the areas such as surface, lap points and fasteners. So, NDT is being needed for this purpose. It includes visual inspection, magnetic particle tests, liquid penetration tests, xray penetration inspection, eddy current inspection and ultrasonic inspection.
The principal behind corrosion includes dispersive waves and velocity is a Fn of frequency thickness product. The maternal changes which affects the 2 layers includes propagating mode amplitude, velocity, frequency and the time of flight.
Different wave modes can be tested via two methods which includes echo mode as well as the pitch mode. The kind of modes include narrow band waves as well as high power to launch over distance waves.