Non-destructive testing investigation of gaps in thin Glare laminates

ABSTRACT

The manufacturing of Fibre Metal Laminates, consisting of alternating layers of pre-preg fibre and metal is complex, and defects can be introduced during manufacturing. The automation of the manufacturing steps is vital for future Glare production, and specific defects have to be considered. Among them, gaps between pre-preg plies represent a potential risk for the mechanical performances of the laminate. In this paper/research, non-destructive testing based on ultrasonic inspections are performed on Glare with pre-preg gaps in order to extend and improve the current state of the art to different pre-preg gap widths, depths, and lay-ups. Firstly, gaps were introduced in Glare specimens. Then, a conventional C-scan ultrasonic inspection is performed. In order to overcome the current limitations of a top or planar view of the laminates, the evaluation of the depth of the gaps in the laminates is performed by means of phased array ultrasonic testing. Finally, images of the laminate cross-section have been collected in order to provide a meaningful evidence of the ultrasonic-based analysis. Results from different Glare and gap widths and depths show the accuracy of the proposed investigation which is able to provide a detailed assessment of the gap occurrences also for very thin laminates.

KEYWORDS:

• Glare
• NDT
• defects
• gaps
• phased array ultrasonic testing

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This paper resulted as a collaboration between Delft University of Technology and Lublin University of Technology. The research was carried out under project number T11.6.14523 in the framework of the Research Program of the Materials innovation institute (M2i) (www.m2i.nl) supported by the Dutch government and Fokker Aerostructures, and in the framework of the project Lublin University of Technology-Regional Excellence Initiative, funded by the Polish Ministry of Science and Higher Education (contract no. 030/RID/2018/19).