Creep, cracks, delaminations, and material identification.
Our unique and patented non-linear acoustic NDT capability can detect flaws in materials which no other NDT technology can see – of the order of a few microns wide. The sensitivity is so fine that we can also distinguish between two related base materials – two different grades of aluminium, for example.
Case study: Detection of kissing bonds in friction stir welds.
We scanned the length of a friction stir weld to produce a Thetagram – a ‘heat map’ of non-linearities in the weld. At three locations along the weld we identified different levels of response (green-yellow-red) and wire-cut small samples from the metal. Using Scanning Electron Microscopy we confirmed the presence of cracks of the order 100um x 1um in size.
The Thetagram is produced by our Pulse Inversion NDT system. This applies two time-separated swept-frequency pulses and records the responses of the test-piece. These two responses are summed to produce a residual waveform. If the test-piece has a linear response (i.e. is free of cracks) the residual will be zero. If the test-piece contains cracks, the response will be non-linear and the residual will contain harmonics of the input signal. No conventional NDT system (including X-ray) can provide this level of detection sensitivity. Theta’s mission is to create customer solutions to specific NDT problems in the manufacture, maintenance and management of both composite and traditional materials, and bonds and welds between them.
Integral to our continued drive for innovation is the in house research that we undertake to continue to push the boundaries of what our technology can achieve. A selection of our papers, detailing the technology, background and capability behind our products and services can be found in our research section.