A new technique that examines materials for cracks and weaknesses could help rescuers assess buildings for earthquake damage and help engineers design better earthquake-proof buildings. The technique measures sound waves as they pass through a material, monitoring the changes in tone and resonance caused by cracks or deformations allowing engineers to monitor the safety of all kinds of structures including buildings, bridges, oil pipelines, aircraft and engine parts.
Cracks in a material cause a sound wave passing through the object to change in frequency in a similar way to a cracked bell producing a dull tone. By applying different frequencies to the object, engineers can build up a clear picture of whether or not a material contains any internal damage without having to take the object apart to examine it.
"Using a frequency spectrum analysis, we can easily tell the difference between a damaged and an undamaged object," says Paul Johnson, part of the research team at Los Alamos National Laboratory, USA. The technology, known as Nonlinear Resonant Ultrasound Spectroscopy (NRUS), is breaking new frontiers in the non-destructive testing of materials and promises to be the most sensitive, rapid and easy-to-apply method for detecting and examining material damage.
"We are currently developing a method that will not only diagnose damage, but also locate the damage," says Johnson, "There are potentially a huge number of applications with an enormous economic and safety impact that will evolve from nonlinear applications."
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Notes For Editors
- This item is due to appear in the September issue of Materials World, Volume 7, Issue 9 on page 544.as "The new wave in acoustic testing" by Paul Johnson.
- Materials World is the journal of The Institute of Materials, the professional organisation of materials scientists, engineers and technicians working throughout the world in areas involving the use and application of plastics, rubber, metals, composites and ceramics.
- Brief contents of Materials World are also available on the web: www.materials.org.uk
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