Sunday, October 12, 2014

New imaging technique could detect acoustically ‘invisible’ cracks

The development of a new imaging technique  by researchers from the University of Bristol’s Ultrasonics and Non-destructive Testing (NDT) research group promises to be able to detect damage previously invisible to acoustic imaging systems which could lead to aircraft off the future being thinner and lighter. 

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 important method.  Engineers are currently able to produce images of the interior of components using ultrasound, but can only detect large problems such as cracks. 

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.
Commenting on the project, study lead, Dr Jack Potter, research assistant in the Department of Mechanical Engineering said: “Imaging acoustic nonlinearity not only provides sensitivity to smaller defects than is currently possible but may have the potential to detect damage before macroscopic material changes occur.  This would enable intervention before cracks have even begun to form, as well as predicting the remaining life of an engineering structure.  Crucially the technique has been achieved using standard inspection equipment, which will allow for the rapid implementation of the technique in numerous applications.”
Such advances in non-destructive evaluation not only increase the safety of engineering structures but can help future design, for example, allowing the next generation of aircraft to be built thinner and lighter. 
The study was supported by the UK Research Centre in Non-destructive Evaluation (RCNDE).