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Virtual ultrasonic testing to the fore

Connect, no. 132, September/October 2004, p.8

FE model prediction of reflection from angled crack
FE model prediction of reflection from angled crack

A finite element (FE) model of short-range ultrasonic testing (UT) has recently been developed by TWI.

It enables prediction and visualisation of ultrasonic inspections and is a powerful tool for applications ranging from the design of inspection strategies, to use as a training aid. Such capabilities will improve safety in industries like aerospace, nuclear or oil and gas.

The FE model provides a complete general prediction of the propagation of sound energy through materials. The prediction is transient so visual results are available at all points in time.

The FE model is able to predict all ultrasonic phenomena, including interactions with the back wall or sidewalls, signals that arise from multiple scattering and/or mode conversion to shear waves or surface (Rayleigh) waves. An example of an FE modelling result at one point in time is shown in the figure.

There are already analytical models available for modelling short range UT. Such models are widely used but have certain limitations.

TWI's tools have the advantage over analytical codes of being able to examine issues such as: small flaws (with dimensions less than two wavelengths), composite materials, near-field, anisotropy and reduced probability of detection caused by residual compressive stresses.

The tools have been validated for the simulation of ultrasonic inspection of angled cracks. The prediction from the finite element model has been compared with an extensive experimental data set. The difference was found to be less than 0.8dB.

Applications for the tools include inspection design and optimisation, technical or safety justifications and UT qualification and performance demonstration. Animated visual predictions of the wave propagation are used to help TWI's Members with physical insight, simulation and training.

To learn more, why not contact Ruth Sanderson. E-mail:

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