Development of the symmetrical laser shock test for weak bond inspection

This study aims to assess the capability of the LAser Shock Adhesion Test to detect weak bonds in assemblies made of carbon fibre reinforced polymer laminates as well as understand the behaviour of different bonded composite structure under a shock load. A specific setup based on symmetrical laser shocks has been used. After each test, ultrasounds are used to determine if the bond has been damaged or not. At first, samples with two contaminants - de-icing fluid and finger prints - were studied. Then, the bond quality of two partially contaminated aircraft parts were investigated. These original results demonstrate the efficiency of the symmetrical laser shocks method as a Non-Destructive Test for bonded carbon fibre reinforced polymer assemblies

Détection des joints faibles par des techniques de choc produit par laser

The limitation of carbon dioxide emissions is one of today’s greatest challenges for the aerospace industry. Weight reduction is seen as one of the most promising lead for that matter and a first step has already been made toward this goal through the use of composite materials. Lighter and more mechanically efficient than their metallic counterparts, their use helped optimising the weight of several aircrafts such as the A350 XWB or A380. Nevertheless, if the material has changed, the assembly process did not evolve along with it. Hence, techniques such as riveting or bolting previously used for metallic structure are still used for composite parts assembly, but they are not suitable anymore for this type of material (creation of local constraints, corrosion, …). Instead, bonding composite parts using adhesives would be a better solution and could help further reducing the overall weight of the aircraft. However, with this new assembly method also come new problems, such as weak bonding. A weak bond is characterised by a loss of mechanical adherence that cannot be spotted using conventional Non-Destructive Tests (NDTs) such as ultrasound scanning. Since the industry currently lacks these NDTs to assess the mechanical integrity of bonded structures, the use of adhesives for composite assembly is limited.The LAser Shock Adhesion Test (LASAT), has already demonstrated its capacity to evaluate bonded composite assembly but also proved to be limited in terms of assembly configuration and weak bond detection capability. This work focuses on one of its optimisations, the Symmetrical LASAT (S-LASAT). Both experimental and numerical studies are realised to better understand the prerequisites of the technique as well as the level of mastery required for the technology to best detect weak bonds within Carbon Fibre Reinforce Polymer (CFRP) structures. This manuscript concludes with a one of a kind experimental campaign realised on real bonded CFRP aircraft parts.L’une des grandes problématiques actuelles des secteurs aéronautique et spatial est la réduction du taux d’émission de CO2. Une des solutions est l’allègement et l’optimisation des structures. Dans cette optique, certains avions comme l’a380 ou l’a350 XWB ont été fabriqués en grande partie à l’aide de matériaux composites. Plus résistants et plus légers, ils permettent un gain de poids important comparés aux matériaux métalliques. Cependant, ces pièces composites sont encore assemblées à l’aide de rivets ou de boulons. Ces procédés non adaptés aux matériaux composites limitent le gain de poids que pourrait engendrer leur utilisation. L’emploi de colles en revanche permettrait ce palier à ce problème, permettant ainsi de réduire de manière plus efficace le poids des structures. Cependant, ce procédé peut aussi être à l’origine de la création de joints faibles. Un joint est qualifié de faible quand sa tenue mécanique est inférieure à sa tenue nominale prévue. Actuellement, l’absence de Control Non Destructif (CND) permettant d’évaluer les propriétés mécaniques de ces pièces collées est l’un des principaux verrous à l’utilisation de ce procédé d’assemblage.Le Test d’Adhérence par Choc Laser (LASAT) a déjà prouvé sa capacité à évaluer la tenue mécanique de joints de colle dans des structure en Polymère Renforcé de Fibres de Carbone (PRFC). Cependant il ne peut s’appliquer qu’à quelques géométries d’assemblage spécifiques et a aussi démontré des limites en termes de détection de joint faible. Ce travail propose une étude expérimentale et numérique d’une des optimisations du LASAT : le Test d’Adhérence par Choc Laser Symétrique (S-LASAT). Le but est d’approfondir la compréhension de la physique mise en jeu afin de mieux appréhender les prérequis nécessaires à la technologie pour détecter les joints faibles. Cette étude conclura sur une étude unique de test d’adhérence réalisée sur de vraies pièce aéronautiques collées

Development of the symmetrical laser shock test for weak bond inspection

International audienceThis study aims to assess the capability of the LAser Shock Adhesion Test to detect weak bonds in assemblies made of carbon fibre reinforced polymer laminates as well as understand the behaviour of different bonded composite structure under a shock load. A specific setup based on symmetrical laser shocks has been used. After each test, ultrasounds are used to determine if the bond has been damaged or not. At first, samples with two contaminants - de-icing fluid and finger prints - were studied. Then, the bond quality of two partially contaminated aircraft parts were investigated. These original results demonstrate the efficiency of the symmetrical laser shocks method as a Non-Destructive Test for bonded carbon fibre reinforced polymer assemblies

Extended Non-destructive Testing for the Bondline Quality Assessment of Aircraft Composite Structures

International audienceAbstract We present the results of extended non-destructive testing (ENDT) methods for bond line quality assessment in adhesive joints. The results presented were derived for important application scenarios with regards to aircraft manufacturing and the in-service repair of composite structures. The electromechanical impedance (EMI), laser shock adhesion testing (LASAT), and nonlinear ultrasound scanning (NUS) were used on flat coupon samples, scarfed samples, and curved samples. The EMI method applied to the flat coupons showed some relation of the frequency shift to the level of contamination. For the curved samples, there was insufficient sensitivity to differentiate distinct levels of contamination, while for scarfed samples in most cases both detection and distinction were possible. The LASAT method gave good results for the coupon samples, which were also in accordance with the results of the $${\text{G}}_{\text{IC}}$$ G IC and $${\text{G}}_{\text{IIC}}$$ G IIC tests. For coupon samples with multiple contaminations, we obtained results with varying significance. In the case of NUS, the measurements revealed an increase in nonlinearity affected by contamination at the interphase between the CFRP adherend and the adhesive layer for the majority of scenarios comprising single contamination of flat coupons and scarfed samples. The effect of multiple contaminations was a decrease in nonlinearity for the curved samples

Extended Non-destructive Testing Technique Demonstration in a Realistic Environment with Technology Assessment

Abstract This chapter highlights two advances towards a higher maturity of versatile extended non-destructive testing (ENDT) procedures. Full-scale demonstration tests are presented in realistic user application cases that involve typical production or repair scenarios. Subsequently, the investigations used to assess the probability of detection (POD) are detailed for the respective ENDT processes and application-relevant scenarios in a realistic environment. Although some results indicated that some additional in-depth investigations would be even more enlightening, these demonstrations still clearly showed that developments and progress described in the previous chapters have enabled some of the technologies to achieve a maturity that is sufficient to proceed towards industrial implementation. Some ENDT techniques revealed the presence of contaminants on real structural parts with unknown contaminant amounts. For the first time, POD results obtained for ENDT investigations are presented. Some ENDT procedures permitted POD results to be obtained for several scenarios, while others showed technologically relevant POD only for certain scenarios. For two ENDT techniques, determining the POD helped to enhance the respective testing and evaluation procedures. In most of the cases, it was possible to estimate a preliminary quantification of POD by giving the POD90/95. For some techniques, this value was below the lowest contamination degree

Association of diabetes and outcomes in patients with COVID-19: Propensity score-matched analyses from a French retrospective cohort

International audienceBackground: Our study aimed to compare the clinical outcomes of patients with and without diabetes admitted to hospital with COVID-19.Methods: This retrospective multicentre cohort study comprised 24 tertiary medical centres in France, and included 2851 patients (675 with diabetes) hospitalized for COVID-19 between 26 February and 20 April 2020. A propensity score-matching (PSM) method (1:1 matching including patients' characteristics, medical history, vital statistics and laboratory results) was used to compare patients with and without diabetes (n = 603 per group). The primary outcome was admission to an intensive care unit (ICU) and/or in-hospital death.Results: After PSM, all baseline characteristics were well balanced between those with and without diabetes: mean age was 71.2 years; 61.8% were male; and mean BMI was 29 kg/m2. A history of cardiovascular, chronic kidney and chronic obstructive pulmonary diseases were found in 32.8%, 22.1% and 6.4% of participants, respectively. The risk of experiencing the primary outcome was similar in patients with or without diabetes [hazard ratio (HR): 1.16, 95% confidence interval (CI): 0.95-1.41; P = 0.14], and was 1.29 (95% CI: 0.97-1.69) for in-hospital death, 1.26 (95% CI: 0.9-1.72) for death with no transfer to an ICU and 1.14 (95% CI: 0.88-1.47) with transfer to an ICU.Conclusion: In this retrospective study cohort of patients hospitalized for COVID-19, diabetes was not significantly associated with a higher risk of severe outcomes after PSM.Trial registration number: NCT04344327

Relation of outcomes to ABC (Atrial Fibrillation Better Care) pathway adherent care in European patients with atrial fibrillation: an analysis from the ESC-EHRA EORP Atrial Fibrillation General Long-Term (AFGen LT) Registry

International audienceAbstract Aims There has been an increasing focus on integrated, multidisciplinary, and holistic care in the treatment of atrial fibrillation (AF). The ‘Atrial Fibrillation Better Care’ (ABC) pathway has been proposed to streamline integrated care in AF. We evaluated the impact on outcomes of an ABC adherent management in a contemporary real-life European-wide AF cohort. Methods and results Patients enrolled in the ESC-EHRA EURObservational Research Programme in AF General Long-Term Registry with baseline data to evaluate ABC criteria and available follow-up data were considered for this analysis. Among the original 11 096 AF patients enrolled, 6646 (59.9%) were included in this analysis, of which 1996 (30.0%) managed as ABC adherent. Patients adherent to ABC care had lower CHA2DS2-VASc and HAS-BLED scores (mean ± SD, 2.68 ± 1.57 vs. 3.07 ± 1.90 and 1.26 ± 0.93 vs. 1.58 ± 1.12, respectively; P < 0.001). At 1-year follow-up, patients managed adherent to ABC pathway compared to non-adherent ones had a lower rate of any thromboembolic event (TE)/acute coronary syndrome (ACS)/cardiovascular (CV) death (3.8% vs. 7.6%), CV death (1.9% vs. 4.8%), and all-cause death (3.0% vs. 6.4%) (all P < 0.0001). On Cox multivariable regression analysis, ABC adherent care showed an association with a lower risk of any TE/ACS/CV death [hazard ratio (HR): 0.59, 95% confidence interval (CI): 0.44–0.79], CV death (HR: 0.52, 95% CI: 0.35–0.78), and all-cause death (HR: 0.57, 95% CI: 0.43–0.78). Conclusion In a large contemporary cohort of European AF patients, a clinical management adherent to ABC pathway for integrated care is associated with a significant lower risk for cardiovascular events, CV death, and all-cause death