The University of Bristol, U.K., announces that its researchers have developed a nonlinear acoustic imaging technique that can detect cracks that cannot be seen by conventional acoustic imaging methods. Imaging of acoustic nonlinearity is achieved by exploiting differences in the propagation of fields produced by the parallel and sequential transmission of elements in ultrasonic arrays.
It has long been understood that acoustic nonlinearity is sensitive to many physical properties, including material microstructure and mechanical damage. The lack of effective imaging has, however, held back the use of this method.
Currently engineers are able to produce images of the interior of components using ultrasound, but can only detect large problems such as cracks. This is like detecting only broken bones in a medical environment.
The nonlinear imaging method would enable intervention before cracks have even begun to form, as well as predicting the remaining life of an engineering structure. The technique has been achieved using standard inspection equipment, which will allow for the implementation of the technique in numerous applications.
