Comparison of two non destructive tests in carbon/epoxy composites

An investigation of two nondestructive methods (ultrasounds and infrared thermography) is carried out. The defect detection by both methods is first examined. The determination of the position and dimensions are then studied. And finally, the feasibility and the time of the experimental protocol setting up is analysed. The aim is to compare two nondestructive methods: ultrasound and infrared thermography applied to composites samples. So, three different specimens are tested. It appears that the majority of the defects are detected very quickly with infrared thermography compared to ultrasounds method. However, certain defects are not visible by thermography IR

Impact damage evolution under fatigue loading by InfraRed Thermography on composite structures

This study deals with cumulative damage and its evolution in already impact damage composite structure. In order to follow the growing damage and to compare it with cumulative model, tests are monitored with an InfraRed thermography system. A carbon-epoxy composite is first low-energy impacted and then fatigued under tension-compression loading. This study also enables a very fast analysis of predicting the damage evolution coupling InfraRed Thermography as NDT method and InfraRed thermography as a following system

Non destructive investigation of defects in composite structures by three infrared thermographic techniques

This paper investigates full-field measurement techniques based on Infrared Thermography for Non Destructive Testing (NDT) applications on composite materials. Three methods have been implemented and the paper intends to characterize and compare their defect detection limit and related specific application fields. Various composites have been considered in this study, namely laminates and sandwich structures, in order to address many important issues of performance assessment for the aviation industry

Application of non destructive testing to the detection of aeronautical defects in composite structures

A study of two Non-destructive Testing methods (NDT) was carried out in specimens with different kinds of simulated defects. Ultrasonics test (US) and Infrared Thermography (IRT) were applied with the aim to evaluate the detectability and the accuracy of each method.These techniques have acquired great importance in the aeronautics industry because they allow to control the aerostructures without intervening in their physical and mechanical integrity. In the second part of the study, a comparison of both techniques was achieved in order toanalyse their limits and advantages. It appeared that detectability of defects was much better in a sample with flat-bottomed holes defects in the case of Ultrasonic Test. However it was found that Infrared Thermography is much more limited to the thickness of the specimen than the ultrasonic waves. On the other hand, defects were all revealed with IRT in a sandwich composite including Teflon inserts, which was not the case for US

Caractérisation et comparaison des limites de détection de techniques de contrôle non destructif : méthodes ultrasonores et méthodes optiques

Le contexte de ce travail concerne le process d’Infusion de Résine Liquide (LRI) développé dans le cadre du projet « FUSelage COMPosite » par DAHER SOCATA. Ce process de fabrication permet de réaliser des pièces de formes complexes et des panneaux entiers de fuselage composite ce qui réduit considérablement les étapes d’assemblages et donc les temps de production. Ce travail porte sur l’inventaire de toutes les méthodes de contrôle non destructif pouvant être appliquées aux structures composites fabriquées en LRI dans le but de définir leurs limites de détection des défauts et leurs champs d’applications spécifiques. Dans l’aéronautique, les standards AITM imposent les ultrasons comme méthodes de contrôle non destructif sur les structures composites. Par conséquent, le but de ce travail est de caractériser et comparer plusieurs méthodes de contrôle sans contact telles que les méthodes ultrasonores disponibles au laboratoire IUT-ICA et les méthodes optiques disponibles au laboratoire ENIT-LGP afin de déterminer leurs limites de détection, leurs complémentarités et leurs champs d’applications spécifiques. Les différents tests sont réalisés sur des éprouvettes composites monolithiques et sandwichs, en LRI et préimprégné, avec différents types de défauts

Damage of woven composite under translaminar cracking tests using infrared thermography

The aim of this work is to increase the study of the notch translaminar propagation of the woven structures, using the InfraRed Thermography (IRT). A test of notch propagation under quasi-static traction was developed and used to study the failure phenomena on two different draping sequences. For each study, a local estimation of dissipated energies, associated with different damages, is carried out using the measurement of the surface temperature field. The study of heat source fields combined with micrographic observations allowed to define the matrix micro-cracking as the predominant damage phenomenon in crack tip. The critical energy release rate, obtained using IRT, corresponds to critical energy release rate reported in the literature for translaminar rupture of laminates. Furthermore, when brittle cracking develops in a thermosetting matrix laminate, the majority of irreversible mechanical energy (>90%) is dissipated as heat. In the case of brittle cracking, the developed method proves to be an efficient alternative technique for the local measure of energy release rate, even in cases where the variations in stiffness due to cracking phenomena remain low

Fatigue behaviour of impacted composite structures

The aim of this study was to compare the mechanical behavior of different impact-damaged composite materials. Three composite materials were realized using the Liquid Resin Infusion process (LRI) accord- ing to three different cycles of polymerization. Thus the temperature of the glass transition of the resin was controlled and the influence of this parameter was then determined. In accordance with the aeronautical use of composite materials, the plates were subjected to Barely Visible Impact Damage (BVID). Two experimental methods were developed to ensure that impact condi- tions were respected. The first method, using the numerical digitalization of surfaces made it possible to reconstruct the defect. Thus the residual indentation could be measured. This indentation had to be lower than 0.3 mm. The second method, using passive infrared thermography, enabled the thermal cartography on the surface to be determined. The size of the damage area was then obtained. Through the use of these two methods, the best cycle of polymerization was determined and fatigue tests were carried out to estimate the evolution of the defect. For this purpose and in compliance with impact and fatigue testing standards, a new and adapted sample was imagined (FAI sample). The fatigue testing conditions were determined to avoid buckling effects and to limit the rise of the temperature of the sample. An experimental method using infrared thermography was then developed to follow the size evolution of the defect. This real time evolution was then compared to the loss of rigidity of the sample

Non destructive investigation of defects in composite structures by fullfield measurement methods

This paper presents different interests of non destructive full-field measurement. More precisely, it focuses on the characterization and the comparison of the X-ray tomography and two methods of infrared thermography in order to define the defect detection limits and to precise the specific application fields for each technique on multi-layered and sandwich composite structures. The obtained results are qualitatively and quantitatively analyzed

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

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-situ 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

Behaviour and damage of injected carbon-fibre-reinforced polyether ether ketone: From process to modelling

International audienceShort-carbon-fibre-reinforced polyether ether ketones are materials of great interest for the aeronautical industry. In this study, a design of experiment was carried out to understand the effect of process parameters on micro- and macro-scale properties of injection-moulded short-carbon-fibre-reinforced polyether ether ketone (90HMF40). Mould temperature was found to be the most significant parameter; it had a positive effect, essentially on failure stress and strain. Once the damage and plasticity scenarios were understood, a micromechanical model based on Mori-Tanaka homogenization theory was developed, featuring micro-damage and coupling with macro-plasticity. This model gave good predictions for quasi-static tensile tests