Lamine Boubakar's research while affiliated with University Bourgogne Franche-Comté and other places

Publications (60)

Article
Various papers in the open source literature have shown that the tensile properties of plant fibres are very scattered. To date, this difference has been viewed as an obstacle to the use of biobased composites in structural applications. However, this question of dispersion has yet not been extensively addressed at the composite scale. Therefore, t...
Article
Despite the great similarities in the physical and chemical properties of flax and primary hemp fibres, literature generally reports differences in their average tensile properties. This work proposes a numerical investigation of the relationships between the morphological, biochemical and cell wall features, along with their variability, and the m...
Article
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Experimental observations have shown that most of plant fibres are characterised by an intricate structure, morphology and organisation. This complex geometrical characteristics may affect the mechanical behaviour of this kind of natural fibres and contribute to the high variability of their mechanical properties. So, this study proposes a numerica...
Article
Novel high-temperature thermoplastic polymers offer potential advantages over thermoset ones and represent a promising alternative in advanced composite applications. This work proposes to determine the thermal properties and resistance of unidirectional carbon fibre reinforced thermoplastic polyimide composite and to characterize the influence of...
Conference Paper
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Due to the difficulties encountered to predict the long-term behaviour of composite structures in operating conditions, a real-time monitoring of their integrity is required in order to anticipate catastrophic failures. Although the early detection of crack initiation and propagation is beyond the potential of most non-destructive techniques (NDT),...
Article
In Acoustic Emission (AE) applications, the processing of continuous signals resulting from high AE rates or the superimposition of transients emitted from different emission sources, is a major problem. In complex systems like Organic Matrix Composites (OMC) fatigue tests, a high AE activity is produced due to the emergence of several emission sou...
Conference Paper
Full-text available
Natural fibres derived from annual plants are attractive candidates to reinforce organic matrix in high performance composite applications. This use requires an accurate understanding of their mechanical properties and the development of efficient models. In the last years, many efforts were focused on the characterisation of the tensile properties...
Conference Paper
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Le travail expérimental présenté dans ce papier s’attache principalement à caractériser l’influence de l’endommagement cumulé dans un composite sous sollicitation de fatigue sur les signatures acoustiques. L’idée est de suivre la distorsion induite par l’endommagement du matériau composite sur une salve générée par une même source acoustique.
Conference Paper
Acoustic Emission (AE) technique is gaining more and more interest for structural health monitoring (SHM) in polymer-composite materials. Recent literature has shown that using appropriate pattern recognition techniques (PRT), the identification of the natural clusters of acoustic emission data can be obtained. Despite these recent and valuable adv...
Conference Paper
In Acoustic Emission (AE) applications, the processing of continuous signals, which results from high AE rates or superimposition of transients emitted from different emission sources, is a major problem. In complex systems like Organic Matrix Composites (OMC) fatigue tests, a high AE activity is produced due to the emergence of several emission so...
Conference Paper
Full-text available
Acoustic Emission (AE) technique is gaining more and more interest for structural health monitoring (SHM) in polymer-composite materials. Recent literature has shown that using appropriate pattern recognition techniques (PRT), the identifi,cation of the natural clusters of acoustic emission data can be obtained. This work investigates acoustic emiss...
Article
The aim of this paper is to investigate the origin of the diameter-dependence of Young’s modulus in hemp fibres. In view of the considerable experimental difficulties encountered when determining the 3D morphology of elementary fibres, the influence of the fibre morphology and size on the E-modulus is studied using a mathematical model. An approach...
Article
The aim of this paper is to propose a methodology to take into account the influence of uncertain data in structural calculations. A specific method, based on the approximation of the responses as a function of the uncertain data, is proposed. Classical methods from the literature are also considered. The different methods are compared on a simple...
Article
Full-text available
We present a model based on the phase transformation surface of SMA. This model is described per a thermodynamical point of view. We applied this modelling on an experimental part that has been realized by P. Sittner et al. on a nickel titane wire. We had several experimental sets with we could show the performances of our model, in particular when...
Article
The main objective of a typical identification process is to determine the best input parameter set of a given problem for which the cost function is not explicitly known in terms of its associated inputs. In the worst case, the cost function is largely multimodal and needs an efficient identification technique to reach an acceptable solution withi...
Article
Full-text available
This paper presents a unilateral damage model coupled with an orthotropic elastic behaviour, to analyse the cracks closure/opening effect on the behaviour of a plate made of long fibre reinforced polymer matrix. The cracks are supposed to grow along the fibres direction with different opening ways. According to the sign of the stress normal to the...
Article
Full-text available
This paper presents the investigation of elastic behaviour of a multilayer composite tube (tubular part of the cylindrical tank) reinforced by a metal liner under the thermomechanical loading using an analytical simulation. The aim of this study was to highlight the thermal effect on the stresses, strains, and displacements through the thickness in...
Article
Full-text available
This paper presents an analysis of stresses and strains of a multi-layer composite tube (tubular part of the cylindrical tank) reinforced by a metal liner under an internal and external pressure loadings. The analytical procedure of simulation is used for the investigation of the elastic behavior of the structure under pressure. The aim of this stu...
Article
Some computer codes are developed to solve specific industrial problems. For economical reasons, and especially when they are used for parametrical studies, these codes have to be not too time-consumer. However, industrial problems are often complex, involving 3D effects when 3D modelling is often not practicable. So 2D or even 1D modelling have to...
Article
This chapter presents an extension of RL models of pseudoelasticity accounting for large strains. The mechanical model is reformulated in an intermediate configuration to recover a small strain-like format of the constitutive relationship. Alloys capable of undergoing phase transformations between a highly ordered austenitic (parent) phase and a le...
Article
Full-text available
Résumé : La conception en matériaux composites des réservoirs de stockage des hydrocarbures permet de réduire leur poids et leur consommation en carburant des véhicules roulant. Plusieurs composites de grande rigidité sont fabriqués par l'utilisation du procédé d'enroulement filamentaire. Dans plusieurs applications, les réservoirs composites-liner...
Article
Full-text available
This paper presents a unilateral damage model coupled with an orthotropic elastic behaviour, to analyse the closure/opening effect on the behaviour of a representative elementary volume. Indeed, the oriented nature of the cracks along the fibres and the unilateral contact of the cracks lips (according to the opening or closure of cracks) lead to co...

Citations

... L'organisation hiérarchique, depuis l'ultrastructure de la fibre unitaire jusqu'aux lamelles mitoyennes des faisceaux de fibres, complique les démarches multiparamétriques (ultrastructure, morphologie et composition biochimique) en faisant intervenir plusieurs mécanismes complexes. Ces dernières années, l'utilisation de modèles numériques [230,194,191,75,76,237] de plus en plus performants résout dans une certaine mesure cette difficulté en permettant de focaliser l'attention sur certains paramètres et aussi d'identifier les paramètres dont les variations produisent le plus d'effet sur les résultats de la modélisation. Des modélisations multi-échelles prenant en compte l'hétérogénéité radiale et longitudinale de l'AMF et de la force de texture, la phase paracristalline et, si possible, la forme des microfibrilles, permettraient d'approfondir le rôle joué par ces paramètres dans le comportement non-linéaire à la fois des fibres unitaires et des faisceaux de fibres. ...
... In spite of their advantages, NLFs also have shortcomings related to their hydrophilic behavior, which hinders adhesion with hydrophobic polymer matrix composites [8]. Moreover, NLFs are characterized by an intricate structure with variable cross-section dimensions within fibers of the same species [8][9][10], associated with different values of density and tensile strength. As such, investigation of the variation in these properties with the diameter of any NLF might be of utmost importance, aiming for possible industrial applications. ...
... Gabrion et al. investigated the tensile properties of carbon fibre-reinforced high-temperature thermoplastic composite after being exposed to high temperatures. They concluded that thermal degradation occurred at temperatures higher than 400 • C [94]. The interlaminar shear strength was relatively low when the material was exposed to high temperatures. ...
... Hemp fibres and their composites [17,18,19] and plant fibres and their composites in general [20,21] exhibit a characteristic non-linear stress-strain response. While traditional fibre-reinforced composites have a linear stress-strain response showing constant stiffness for over 0.5% applied strain, the stiffness (measured through secant or tangent modulus) of hemp fibre composites can drop by over 30 %, even up to 50%, in the strain range of 0% to 0.4%, due to a low elastic limit of ca. ...
... The sensors, converting the subnanometric displacements into voltage signals, have to be read continuously in order to catch all events originating from the material. The data stream is then segmented using a wave-picking algorithm with the aim to detect damage-related (non-noise) AE signals [9,10,11,12,13,14]. In feature-based interpretation of AE signals, a feature extraction step is performed in which AE signals are represented in a common feature space. ...
... The elastic parameters which can be identified are 1 E , 2 E , 12  , 12 G and 23 G , whereas the shear modulus 23 G cannot be identified with the available tests. It was therefore obtained through the use of an asymptotic homogenization technique [9]. To begin the identification process, each parameter's range was defined and its distribution evaluated, in order to restrict the size of the search domain (See Fig. 5). 1 E , 2 E and 12 G distributions show a preferential zone where the objective function has a low value, hence the size of the search domain used for these three parameters could be reduced, and centered on the peak value of each parameter. ...
... The detailed thermomechanical model used to describe the transition from thermal martensite to stress induced martensite can be found in (Boubakar and Lexcellent, 2002). It is based on three main equations: the kinetic equation, the driving force associated to the reorientation as a function of the strain and the internal interactions, and the heat equation. ...
... Conversely, when control rods are withdrawn, the temperature rises locally, and part of the fuel's pellets and claddings dilate. Because the fuel pellets have a higher temperature (especially in the center) and a higher thermal expansion coefficient than their claddings 7 , their volume evolves more consequently to power variations [27,28]. These power variations may bring pellets into contact with the claddings [29,30], creating mechanical stress that endangers the integrity of the claddings, which is a breach of the first containment barrier of PWRs. ...
... For several decades, many models have been proposed to describe composite behaviour, and especially the asymmetry in traction and compression loads [5,6,7,8]. A previous model of unilateral damage has been developed by the authors [3 ] which was able to report matrix micro-cracking taking account for the cracks states. When cracks were opened, a damaged behaviour was used, when cracks were closed and stuck the virgin behaviour was recovered and when cracks were closed and sliding, virgin behaviour was recovered in compression and damaged shearing behaviour was present. ...
... Various approaches with a focus on detection of characteristic similarities of the recorded AE signals have been published. 18,20,[23][24][25][26][27][109][110][111][112][113][114][115][116][117] As a distinctly different approach, supervised pattern recognition techniques consist of two subsequent stages. In the supervised stage a set of objects with known assignment to the respective classes is prepared. ...