Non-linear resonance as a novel self-referencing NDT method for rapid assessment of components

D Rodriguez Sanmartin and J Wright 

Closed defects such as cracks in metals or delaminations and kissing debonds in composites represent a common problem for well-established manufacturing methods, such as subtractive computer numerical control (CNC) machining, and novel methods such as additive manufacturing.

These defects may be difficult to detect using traditional NDT methods or may require characterisation techniques such as X-ray computed tomography (CT), which are not suitable for production environments due to high costs and protracted inspection times. Moreover, several processing steps, each increasing component cost, may need to be completed before the non-destructive evaluation is even possible. Therefore, there is a general industry need for an NDT method capable of rapid assessment of components at different manufacturing stages.

This paper discusses non-linear resonance (NLR) as a characterisation technique capable of providing a go/no-go rapid assessment in seconds. NLR has the advantage, over other linear resonance-based methods, of being a self-referencing technique, and is therefore capable of exposing defects at early stages of manufacture.

The presentation will give examples of completed systems such as that recently deployed at the Manufacturing Technology Centre.