Advanced defect check to prevent potential 'disaster' from use of new composites

Plane parts made from the constant stream of newly-emerging composite materials will be checked for potentially devastating faults with a new testing method.

Researchers at the TPU Research School of High Energy Physics in Tomsk, Russia, are combining multiple methods to create an advanced flaw detection system for complex and large composite products. The process, which will include resonant ultrasonic simulation, is initially aimed at the aerospace and automotive sectors.

The introduction of new composite materials, which are often used for improved strength-weight ratios, is a challenge for existing testing methods. Materials can contain very small defects such as cracks and separate layers that might be missed – potentially leading to "disaster".

“Every year, new composite materials appear and they challenge existing methods of non-destructive testing,” said project manager Daria Derusova. “Joints between the materials are of particular complexity and importance.”

The new system will combine vibrational, resonant ultrasonic and thermal testing, to make it possible to test large or complex parts while taking their physical properties into account.

Classic ultrasonic and X-ray testing are currently used during production, said Derusova. “The latter is the most accurate but it does not fit to large-sized objects that are presented in aviation a lot. In turn, ultrasonic facilities consume kilowatts of electricity to stimulate materials with a mono-frequency acoustic signal… the developed approach will be an alternative to the existing methods.”

Piezoelectric transducers will send resonant ultrasonic stimulation through components in a wide range of frequencies. A scanning laser Doppler vibrometer will then help identify the different resonant frequencies of any defects. The “intense” vibrations also lead to areas around defects heating up, so an infrared camera with specialised software will check temperature changes to help identify defects’ location, form and size.

The new combination process will use several-times less electricity than high-power ultrasonic installations, the team said. They will build a laboratory testing facility over the course of a two-year, Russian Science Foundation-supported project.

The team will collaborate with peers from the Institute of Strength, Physics and Materials Science, the S.А. Chaplygin Siberian Research Institute of Aviation, the University of L'Aquila in Italy and the Symbiosis Institute of Technology in India.