Short pulses of high frequency ultrasound are propagated by a transducer along a narrow beam into the testpiece. Where the pulses strike the sides of the testpiece or discontinuities within the testpiece, some of the ultrasound is reflected back to the transducer. These echoes are detected and their flight times are measured electronically. Sound propagates through a medium at a constant velocity which is a characteristic of that material. Echo flight-times can therefore be calibrated directly for distance. Echoes are displayed on a LCD Display as graphic image.
Composite Structures
Cracks, delaminations & disbonds to
hull, decks & superstructures. Panels, critical joints with stiffeners and other internal reinforcements.
Carbon Masts & Spars
Cracks, delaminations, disbond within the main structure and at critical reinforcements.
Rigging
Rod rigging coldheads.
Metals
Sizing of shaft pitting.
Condition assessment of chainplates fasteners & keelbolts .
There are some limitations due to the nature of ultrasound. Cored structures (sandwich panels) can generally only be inspected to the first bond line. Bond line of Nomex cored panels is normally not inspectable by standard ultrasound. A clean and even surface is needed to guarantee a good contact between test piece and transducer.
Low-density fillers and other sound-attenuating materials can also affect the performance of ultrasonic waves.
