The detection of aeronautical defects in situ on composite structures using Non Destructive Testing

Abstract

A study of three Non Destructive Testing methods (Ultrasonic Testing, InfraRed Thermography and Speckle Shearing Interferometry, known as Shearography) was carried out on different specific types of composite specimens having a variety of defects. The aim of this study is to evaluate the efficiency of these NDT methods in the detection of in site defects resulting from Barely Visible Impact Damages (BVID) or in-service damages to complex surfaces such as wings or rods. The size and position of all the defects were determined by GVI (General Visual Inspection): GVI being the reference. The evaluation of the three NDT techniques enabled conclusions to be drawn regarding defect detection and size. The first part of the study deals with determining and measuring defects. It appears that only the ultrasonic method enables the depth of a defect to be determined. In the second part of the study, the results obtained by the three NDT methods are compared. Finally, the feasibility and the time taken to set up the experimental protocol are analyzed. The study shows that all the defects were revealed by, at least, one of the three NDT methods. Nevertheless it appears that InfraRed Thermography and Shearography produced results very quickly (in about 10 s) compared to Ultrasonic Testing.

Damage investigation in CFRP composites using full-field measurement techniques: Combination of digital image stereo-correlation, infrared thermography and X-ray tomography

“…whose effects are recovered in reflection or in transmission; a so-called active approach is particularly suitable for NonDestructive Testing (NDT) to reveal internal defects [28][29][30]; and/or deformation of the material itself due to thermoelastic coupling and heat dissipations when the material is affected by irreversible mechanisms [13]; such passive approach is of particular interest for monitoring damage under stress with many applications in fatigue [31,32]; this kind of procedure has been employed in the present study.…”

Development of Infrared Techniques for Practical Defect Identification in Bonded Joints

“…Air coupled ultrasound has also been developed, however results have been mixed and it is generally accepted that this method is less sensitive and more difficult to carryout than conventional UT [54,55]. The point-by-point nature of conventional UT means that scans are reported to be up to 60 times more time consuming [56] than other full field methods such as thermography and shearography [57], which will be discussed in subsequent sections.…”

Technology Review of Thermal Forming Techniques for use in Composite Component Manufacture

“…Other factors that can affect the materials properties of composite components are forming defects such as winkles or fibre defects. These are difficult to detect and are often only found after forming and curing of a part [15].…”