Composite repair

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Réparation des composites par infiltration de résine = Investigation of a composite repair method by liquid resin infiltration

Réparation des composites par infiltration de résine = Investigation of a composite repair method by liquid resin infiltration

Mots Clés : Réparation des composites, infiltration de résine, dommage d'impact, délaminage, fissuration. Keywords : Composite Repair, Liquid Resin Infusion, Impact Damage, Delamination, Crack. 1 Introduction Bien que les composites soient de plus en plus employés notamment dans le domaine aéronautique, l’ensemble des fabricants et utilisateurs de composite sont d’accord sur la sensibilité à l’impact de ces matériaux. [1]. L’origine des dommages peut être de nature très variée (impact de grêle, chute d’outils, choc entre deux panneaux lors de l’assemblage, foudre,…) mais l’origine principale reste liée à un impact. Il est important de préciser, que ce type de sollicitation peut se produire dès la phase de fabrication, pendant les phases d’assemblages et pendant la vie en série du produit composite. Le dimensionnement des pièces composites permet de tenir compte des chargements statiques et en fatigue contrairement aux chargements accidentels qui sont difficiles à prédire. Afin de pallier ce problème, on assiste aujourd’hui à
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Proof of a composite repair concept for aeronautical structures: a simplified method

Proof of a composite repair concept for aeronautical structures: a simplified method

4 Bayab Industries, 10 allée de Longueterre, 31850 Montrabé, France Received: 7 October 2019 / Accepted: 16 June 2020 Abstract. This paper provides an illustration of all stages of primary aeronautical composite structure repair by using industrial tools and scientific methodologies, as well as numerical tools to simplify the cross-over analysis of the mechanical behaviour of the repaired area. Economically and scienti fically speaking, one of the main challenges of composite repair (for monolithic long fiber composite parts) consists of promoting a bonded composite patch option without additional riveted doublers. To address this challenge, size reduction of the patch could be mandatory. A patent (jointly owned by ICA, Bayab Industries and CES), entitled “Method for repairing a wall consisting of a plurality of layers”, is devoted to reducing repair patch dimensions of monolithic composite parts provided the bonding zone has a stepped-lap geometry. This patent is based on a simple idea that no overlapping length is required between composite plies for load transfer except in the fiber directions of the plies (unidirectional or biaxial long fiber reinforcements with epoxy matrix). To prove this concept, we consider on one hand, a situation unusual in the literature by studying a composite specimen without fibers aligned along the main loading axis, and on the other hand, a classical situation of where the shape of the specimen is adapted to be studied by uniaxial tension tests. After different manufacturing steps, the studied specimen contains three zones representing both the in fluence of the total thickness of a repair patch, the stepped-lap area assembled with an adhesive film and the parent composite part. Basically, a simple parent structure consisting of 16 plies of UD Hexply ® M21/35%/268/T700GC (close to Airbus composite raw materials on board in A380) is manufactured with a stacking sequence of [+45/ −45/−45/+45/+45/−45/−45/+45] s .
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Disbond effects on bonded boron/epoxy composite repair to aluminium plates

Disbond effects on bonded boron/epoxy composite repair to aluminium plates

behaviour of a crack repaired by a boron/epoxy patch by computing the stress intensity factor at the crack tip in mode I and mixed mode. The effects of the mechanical and geometrical p[r]

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Quality control evaluation of reinforced sulphur-asphalt composite repair material

Quality control evaluation of reinforced sulphur-asphalt composite repair material

/ La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur. For the publisher’[r]

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Implementation of a new method for robotic repair operations on composite structures

Implementation of a new method for robotic repair operations on composite structures

The aim of this project is the development of an integrated process chain for a fast, low price, automated and reproducible repair of high performance fiber composite structures with a collaborative robot. This platform will be mountable on aircraft structures even in-field, which allows for repairs without disassembly of the part itself. Consequently, a faster, more reliable and fully automated composite repair method is possible for the aeronautical and nautical industry. The objective of this article is to propose a new method to automate repair process of composite parts, for example monolithic CFRP laminate plates representative of primary aircraft structures.
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Infrared signatures of bonded interfaces for the repair of primary structures in composite materials

Infrared signatures of bonded interfaces for the repair of primary structures in composite materials

Keywords: Composite repair, Infrared thermography, Bonding certification A BSTRACT This paper deals with the use of infrared thermography for the reliability evaluation of bonded re- paired composite structures. To address such issue, the present work intends to characterize a heat flow load by inverse identification. In this way, a specific experimental bench is developed to carry out ther- mal tests under controlled conditions. Moreover, the FEMU technique is adopted to identify the heat flow amplitude by means of correlation between experimental and numerical surface temperature fields. Such procedure is used on metallics coupons to identify the heat flow and is validated on carbon fiber laminates with different lay up.
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Infrared signatures of bonded interfaces for the repair of primary structures in composite materials

Infrared signatures of bonded interfaces for the repair of primary structures in composite materials

Keywords: Composite repair, Infrared thermography, Bonding certification A BSTRACT This paper deals with the use of infrared thermography for the reliability evaluation of bonded re- paired composite structures. To address such issue, the present work intends to characterize a heat flow load by inverse identification. In this way, a specific experimental bench is developed to carry out ther- mal tests under controlled conditions. Moreover, the FEMU technique is adopted to identify the heat flow amplitude by means of correlation between experimental and numerical surface temperature fields. Such procedure is used on metallics coupons to identify the heat flow and is validated on carbon fiber laminates with different lay up.
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Mechanical restoration and failure analyses of a hydrogel and scaffold composite strategy for annulus fibrosus repair

Mechanical restoration and failure analyses of a hydrogel and scaffold composite strategy for annulus fibrosus repair

biomechanics to the healthy (intact) condition, ease of delivery, and the potential to be functionalized to deliver cells or drugs in order to promote long-term healing or regeneration. This three part biomechanical study assessed the performance of multiple composite repair strategies using these components evaluated under multiple degree of freedom biomechanical testing using bovine caudal IVD injury models. Part 1 applied a torsional stiffness test to evaluate whether the repair restored AF integrity since mechanical integrity of annulus fibrosus integrity is most sensitive to torsion [9,19]. Part 1 tested the hypothesis that the composite repair strategy with scaffolds would best restore biomechanics to intact levels but the adhesive alone would have the lowest herniation risk. Part 2 selected the most promising repairs from Part 1 and after procedure refinement, evaluated them for herniation risk and biomechanical restoration in axial compression and two bending degrees of freedom. Bending was evaluated since it can rigorously test for herniation risk. Part 2 tested the hypothesis that the FibGen adhesive alone and the composite repair with suturing augmentation could restore biomechanics and disc height loss without risk of herniation. Part 3 used the most successful repair strategies from Parts 1 & 2 and evaluated mechanical restoration using a cruciate-style defect to be more representative of the variety of defects found clinically following herniation and discectomy procedures[12] (rather than biopsy defects) and to evaluate if FibGen could adhere to irregularly-shaped defects. Part 3 used an angle control with moment limits test. in 3 rotational degrees of freedom (i.e., torsion, flexion-extension & lateral bending). Part 3 was performed at the University of Bern (rather than Mount Sinai). Part 3 tested the hypothesis that the FibGen can seal a cruciate-style defect and restore the biomechanical behaviors to intact levels in bending, flexion-extension, and axial rotation.
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Why do maintenance and repair matter?

Why do maintenance and repair matter?

Besides this empirical variety, it is also important to recognise the theoretical potential of maintenance and repair studies, each of their explorations offering an occasion to document original ways of enacting order, identity and authenticity, but also inviting us to denaturalise the relationship between maintenance and order. Whilst one may think that maintaining objects or infrastructures always amounts to bringing things back to order, we saw here that things are not so simple. First, studying maintenance and repair directs attention to the relationality of order (if an order is repaired or maintained, which one is it, from which standpoint?). Second, certain forms of maintenance have less to do with order than with precariousness and the life that emerges in the interstices (or the ruins) of innovation and even capitalism (Tsing, 2015). Maintenance and repair studies also bring ways to unfold and discover power relations from the starting point of the various object ontologies that are enacted in distinct regimes of
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Mortars for repair of traditional masonry

Mortars for repair of traditional masonry

The following gives a list of typical performance requirements. The requirements must be considered as a whole - improvements in one area may reduce performance in another. • Mortar should be no stronger than needed for the structural and durability requirements of the masonry. The long-term compressive strength should be lower than that of the existing masonry units and similar or lower in strength than the existing bedding mortar. Strength specifications should therefore have an upper limit as well as a lower limit. There is a tendency to over specify the strength in the belief stronger is better. Unfortunately although the mortar itself may become more durable it can have a negative effect on the performance of the masonry as a whole. The masonry becomes more rigid and less able to accommodate movement. If any movement takes place cracks may occur through the masonry units as opposed to cracking along the mortar joints. Lower strength mortars will also be easier to remove in future repair and maintenance.
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Scapholunate kinematics after flexible anchor repair

Scapholunate kinematics after flexible anchor repair

The scapholunate joint is one of the keystones of the wrist kinematics, and its study is difficult due to the carpal bones size and the richness of surrounding ligaments. We propose a new method of quantitative assessment of scapholunate kinematics through bone motion tracking in order to investigate scapholunate ligament lesion as well as repair techniques. On 6 intact wrists, steel beads were inserted into the bones of interest to track their motions. Experimental set up allowed wrist flexion extension and radio-ulnar deviation motions. Low-dose bi-planar radiographs were performed each 10 ° of movement for different configurations: 1) intact wrist, 2) scapholunate ligament division, 3) repair by soft anchors at the poste- rior then 4) anterior part. Beads’ 3D coordinates were computed at each position from biplanar X-Rays, allowing accurate registration of each wrist bone. The Monte Carlo sensitivity study showed accuracy be- tween 0.2 ° and 1.6 ° for the scaphoid and the lunate in motions studied. The maximum flexion-extension range of motion of the scaphoid significantly decreased after anterior repair from 73 ° in injured wrist to 62.7 °.
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Complex Chromatin Motions for DNA Repair

Complex Chromatin Motions for DNA Repair

; Korsholm et al., 2019 ; Marnef et al., 2019 ). Relocalization of repair sites to the nuclear periphery is also a response to damaged CAG repeats in budding yeast ( Su et al., 2015 ; Aguilera et al., 2020 ; Whalen et al., 2020 ), collapsed replication forks in yeast and mammalian cells ( Nagai et al., 2008 ; Su et al., 2015 ; Lamm et al., 2018 ; Aguilera et al., 2020 ; Whalen et al., 2020 ), and damaged telomeric or subtelomeric sequences in yeast ( Therizols et al., 2006 ; Khadaroo et al., 2009 ; Cho et al., 2014 ; Chung et al., 2015 ; Churikov et al., 2016 ; Oshidari et al., 2018 ; Aguilera et al., 2020 ). Similar relocalization occurs as a result of persistent/unrepairable DSBs ( Nagai et al., 2008 ; Kalocsay et al., 2009 ; Oza et al., 2009 ; Horigome et al., 2014, 2016 ; Swartz et al., 2014 ; Marcomini et al., 2018 ). In these contexts, relocalization appears to prevent aberrant recombination with ectopic repeated sequences ( Torres-Rosell et al., 2007 ; Chiolo et al., 2011 ; Ryu et al., 2015, 2016 ; Su et al., 2015 ; Caridi et al., 2018a ; Dialynas et al., 2019 ; Aguilera et al., 2020 ) and/or promote alternative repair mechanisms ( Therizols et al., 2006 ; Nagai et al., 2008 ; Khadaroo et al., 2009 ; Oza et al., 2009 ; Horigome et al., 2014, 2016 ; Churikov et al., 2016 ; Aguilera et al., 2020 ) (reviewed in Amaral et al., 2017 ; Caridi et al., 2017, 2019 ; Rawal et al., 2019 ). Further dynamics have been associated with other repair pathways. For example, deprotected telomeres are mobilized in mouse cells to promote non-homologous end- joining (NHEJ) ( Dimitrova et al., 2008 ; Lottersberger et al., 2015 ). Additionally, a few chromosome territories reposition in response to damage in human fibroblasts, perhaps reflecting
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Selecting appropriate repair materials for concrete

Selecting appropriate repair materials for concrete

Microstructural examination revealed that the reference paste comprised mainly fibres, whereas the paste formed with NaOH consisted mainly of plates. In the reference p[r]

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Uncertainty in concrete repair and restoration

Uncertainty in concrete repair and restoration

Uncertainty in concrete repair and restoration Mailvaganam, N. P. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Procedural sequence in repair of buildings

Procedural sequence in repair of buildings

Procedural sequence in repair of buildings Mailvaganam, N. P.; Alexander, T. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Repair Time in Distributed Storage Systems

Repair Time in Distributed Storage Systems

We propose a new analytical framework that takes into account this correlation when estimating the repair time and the probability of data loss. Mainly, we introduce a queuing model in which reconstructions are served by peers at a rate that depends on the available bandwidth. We show that the load is unbalanced among peers (young peers inherently store less data than the old ones). This leads us to introduce a correcting factor on the repair rate of the system. The models and schemes proposed are validated by mathematical analysis, extensive set of simulations, and experimentation using the GRID5000 test-bed platform. This new model allows system designers to operate a more accurate choice of system parameters in function of their targeted data durability.
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Self-repair rejuvenates mechanically stressed microtubules

Self-repair rejuvenates mechanically stressed microtubules

because in the absence of defects microtubules deformed elastically with no fatigue and no repair (Fig. 2f and Supplementary Fig. 7). Exactly how the accumulation of stress at lattice defects alters microtubule architecture and bending stiffness remains a key question. Our data suggest that two processes may operate: a local disassembly spreading from the pre-existing defect (Fig. 4) and a long-range disorganization of the microtubule lattice (Fig. 5). We speculate that structural defects may initiate lattice disorganization by allowing a higher degree of freedom to adjacent protofilaments (Fig. 6). Protofilaments adjacent to the defect have fewer lateral interactions and are thus easier to separate, making their deformation less constrained (Fig. 6b). This favours the propagation of cracks in the lattice as well as protofilament rupture and disassembly (Fig. 6c). These effects contribute to global and local microtubule softening. They can be further amplified in repeated bending sequences, generating microtubule fatigue (Fig. 6c). As the microtubule recovers its original straight shape, owing to the remaining stiffness of the intact protofilaments, separated protofilaments spontaneously realign and progressively re-establish lateral interactions (Fig. 6d). Meanwhile, free tubulin in the medium binds to the newly generated protofilament ends
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Biotechnology, material sciences and bone repair

Biotechnology, material sciences and bone repair

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignemen[r]

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Compatibility performance as a fundamental requirement for the repair of concrete structures with Self-Compacting Repair Mortars

Compatibility performance as a fundamental requirement for the repair of concrete structures with Self-Compacting Repair Mortars

Many authors are working on repair topics and, specifically, on the behaviour of the composite concrete/repair material. Common philosophy states that the repair materials must offer the same properties than the concrete substrate: « Repair like with like » [4]. It should contribute to the durability of the repair operation. However, if this assessment appears to be attractive, it doesn’t take into account the “age” of the material. While the “old” concrete is no more sensitive to shrinkage or creep, the “new” repair material will be submitted to stress/strain effects, directly depending on the evolution of material properties from the beginning. The problem has therefore to be considered as a global problem of compatibility between the two materials (mechanical, chemical, electrochemical and permeability compatibility) [5]. Specifically, in order to characterize the potential deformation compatibility between concrete substrate and repair material, five main parameters have to be known: shrinkage, E modulus, creep, restraint and tensile strength. That means that a simple evaluation of axial shrinkage (ASTM C157) is not enough to predict the behaviour of the composite in real situation.
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Artificial membranes tuning for lymphatic wall repair

Artificial membranes tuning for lymphatic wall repair

IT. INTRODUCTION: Chylothorax is an uncommon form of pleural effusion, which generally occurs after cardiac surgery and almost any surgical operation in the chest. The aim of this project is to develop a bioresorbable vascular patch for lymphatic wall repair [1]. Here, we project to develop new materials (i.e. membranes) having two different levels of porosity [2]. First short tests made with Polycaprolactone (PCL) membranes and PCL was blended with different biocompatible, bioresorbable membranes. It shows that human dermal lymphatic endothelial (HDLEC) cells can bind and spread on certain membrane and not on others suggesting that the chemical structure and the morphology of the membranes is important.
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