National Physical Laboratory

A novel non-linear elastic wave acoustic spectroscopy (NEWS) non-destructive inspection (NDI) method for aeronautic and spacecraft materials and components.

Author(s):
Robinson, D W*, Wright, J*, Gupta, S*, Mottram, T*, Armitage, P*, Gower, M R L, Lodeiro, M J, Gelat, P N, Schwarz, C*
Source:
CEAS Space J., 2016, 8, (1), 35-45
ISSN:
ISBN:
NPL Doc. Ref:
PDB: 8043 | DDB: 7411
Document Type:
Periodical article
DOI:
http://dx.doi.org/10.1007/s12567-015-0104-2

Note: An asterisk after an author's name indicates a non-NPL author.

Abstract:

Current non-destructive inspection (NDI) methods have limitations in their ability to identify certain flaws in complex materials and structures where a defect has not been fully formed, for example a kissing de-bond early-stage defect. Non-linear elastic wave acoustic spectroscopy (NEWS) methods have shown potential to detect early-stage flaws in metals and composites. The objectives of the ESA study reported here were to review the state of the art, then to design and build a breadboard demonstrator "NEWS Imaging" (NEWSI) non-linear acoustics instrument, and finally to demonstrate its capability using well-characterised reference defect artefacts (RDAs). A multi-mode NEWSI instrument was produced with the following modes of operation: (a) single and dual frequency, (b) pulse inversion, and (c) resonance drift modes. The first two are suitable for C-scan style imaging by contact testing or with the NACE (air-coupled detection) mode. A set of RDAs were sourced or manufactured, the most important of which was the development of successful kissing de-bonds; areas of significantly reduced bond strength, created in the bond-line between the composite laminates. All the RDAs were characterised by a wide range of complementary NDI methods, and the best results in terms of detection of all the known flaws was the scanning acoustic microscopy ultrasonic C-scan method. This technique detected all of the RDA defects except for kissing de-bonds. The NEWSI instrument was shown to be capable of detecting, with a certain degree of repeatability under controlled conditions, early-stage defects (kissing de-bonds) in composite materials. No other NDI method is known to detect these defect types. The results so far are encouraging and have potentially a lot of interest for ESA and the wider industry, if the unique capabilities of the NEWSI instrument demonstrated on the kissing de-bonds could be developed into a "routine practical test instrument". The target of the next stage of work is to bring the technology readiness level of the instrument up to pre-production levels of development.

Request This NPL report

Please log in or register to access this functionality.

Further Information

General information about NPL publications and details to contact the British Library for other published papers can be found on the NPL Publications Homepage.

Registration

Please note that the information will not be divulged to third parties, or used without your permission

Login