Babcock ultrasonic technique can identify defects in the composite laminate or the area between the substrate and laminate.
Babcock ultrasonic technique can identify defects in the composite laminate or the area between the substrate and laminate.

With the new ultrasonic examination method (based on the application of existing equipment modified in-house), Babcock can identify discontinuities, flaws, air pockets, creases or foreign bodies in laminate or the area between the substrate and laminate that could affect the performance of the composite repair.

With the new technique we can provide customers with the confidence that structural rehabilitation using composites can be assured as a permanent solution (with the often considerable time and cost savings that brings), rather than a temporary fix to be replaced at a later date with conventional material components. With the ability to monitor, and to react to emerging defects should they arise, we are now able to offer long term asset integrity management of our solutions.
David Coumbe, general manager, Babcock Composites Technology

Trials of the new technique have been carried out multiple laminates manufactured from various resins reinforced with glass and carbon fibres. According to Babcock, when compared to existing composite NDE techniques, the clarity of the images produced is much better, showing the individual plies of the laminate. Babcock’s method is potentially capable of identifying the actual type of defect.

The trials also proved that examinations can be carried out through substrates of mild steel up to 10 mm thick to examine the laminate and bond line. The metallic substrate below the repair can be clearly seen, along with a good indication of its thickness. The ability to monitor any further substrate degradation can be a useful means of risk assessment.

Babcock Composites Technology's general manager David Coumbe points out that further work is now needed to quantify the results and prove the accuracy of the substrate thickness measurement.

“Currently, in order to produce an accurate thickness measurement of both the composite and the substrate, two scans are required taking into account the different speeds of sound in the two materials,” he explains.

“Having said that, with the equipment setup for the examination of the composite we can clearly view the substrate, and identify any variations in thickness. Using dedicated analysis software we can effectively ‘zoom in’ through the material viewing each ply within the laminate and view areas of particular interest.”

About Babcock

Babcock is a supplier of engineering, design, build and through life support solutions for both the defence and commercial marine markets. It uses advanced composite materials for the manufacture of structures and for the strengthening and repair of existing assets.