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Capability of non-destructive techniques in evaluating damage to composite sandwich structures

Petr Bělský (Department of Strength of Structures, VZLU – Czech Aerospace Research Centre, Prague, Czech Republic)
Martin Kadlec (Department of Strength of Structures, VZLU – Czech Aerospace Research Centre, Prague, Czech Republic)

International Journal of Structural Integrity

ISSN: 1757-9864

Article publication date: 7 June 2019

Issue publication date: 19 July 2019

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Abstract

Purpose

Defects can be caused by a number of factors, such as maintenance damage, ground handling and foreign objects thrown up from runways during an in-service use of composite aerospace structures. Sandwich structures are capable of absorbing large amounts of energy under impact loads, resulting in high structural crashworthiness. This situation is one of the many reasons why sandwich structures are extensively used in many aerospace applications nowadays. Their non-destructive inspection is often more complex. Hence, the choice of a suitable non-destructive testing (NDT) method can play a key role in successful damage detection. The paper aims to discuss these issues.

Design/methodology/approach

A comparison of detection capabilities of selected C-scan NDT methods applicable for inspections of sandwich structures was performed using water-squirt, air-coupled and pitch-catch (PC) ultrasonic techniques, supplemented by laser shearography (LS).

Findings

Test results showed that the water-squirt and PC techniques are the most suitable methods for core damage evaluation. Meanwhile, the air-coupled method showed lower sensitivity for the detection of several artificial defects and impact damage in honeycomb sandwiches when unfocussed transducers were used. LS can detect most of the defects in the panels, but it has lower sensitivity and resolution for honeycomb core-type sandwiches.

Originality/value

This study quantitatively compared the damage size indication capabilities of sandwich structures by using various NDT techniques. Results of the realised tests can be used for successful selection of a suitable NDT method. Combinations of the presented methods revealed most defects.

Keywords

Acknowledgements

The research leading to these results was funded by the institutional support for the long-term conceptual development of a research organisation provided by the Ministry of Industry and Trade of the Czech Republic.

Citation

Bělský, P. and Kadlec, M. (2019), "Capability of non-destructive techniques in evaluating damage to composite sandwich structures", International Journal of Structural Integrity, Vol. 10 No. 3, pp. 356-370. https://doi.org/10.1108/IJSI-10-2018-0067

Publisher

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Emerald Publishing Limited

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