3D images register ultrasonic wave test signals
Researchers at the Fraunhofer Institute for Nondestructive Testing IZFP have developed a components testing solution where 3D images that register the tiniest tears or flaws detected through ultrasonic waves are generated, similar to medical ultrasound computed tomography.
"These pictures reveal any material defects, giving us their size and exact location," said Professor Hans-Georg Herrmann of Fraunhofer IZFP. The photographs help eliminate the time consuming process of manual data evaluation that is usually involved in testing components using ultrasound.
The solution builds on phased array technology, which includes several single-element probes arranged side by side into rows or sheets. This allows the ultrasonic waves to be passed through large areas of material at a time instead of only penetrating the subject selectively.
The researchers made possible the separate control of each probe to allow engineers to focus on every part of the area being tested simultaneously. In parallel, an algorithm was developed for generating a 3D image, which can then be viewed on a PC, from the many individual signals.
"The spatial resolution of these images is significantly better than in conventional methods. What's more, our reconstruction algorithm is real-time capable, which allows us to significantly speed up the testing process," said Herrmann.
The probe generates ultrasonic waves that penetrate the material. Source: Uwe Bellhäuser
The process is robot-assisted as well, facilitating the testing of materials that have historically been difficult to characterise. Inspecting fibre-reinforced high-performance polymers with direction-dependent fibre orientation is typical of the kinds of application suitable for this testing technology.
To analyse an abnormality in the material, the engineer can view the pictures from different directions, rotate them or select specific areas. It is also possible to take longitudinal or transverse sections of the images.
In industrial applications, large automated component testing can be achieved by enabling an industrial robot, connected to the inspection system via an interface, to carry out complete component scans. The 3D views generated would then be automatically evaluated using specialised, adapted algorithms, thereby easing the burden on the engineer.
Quality assurance is only one example of the possible applications for this solution. "Our technology is suitable for use over the entire product life cycle – from material characterisation to component parts evaluation, from repair services to recycling," says Professor Bernd Valeske of Fraunhofer IZFP.
Currently, the process is being qualified as part of an industrial project and is on the verge of being released. The Fraunhofer researchers will be showcasing a demonstrator of their test system at the Hannover Messe on April 7-11.
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