Salim Chaki

Institut Mines-Télécom | telecom-sudparis.eu · Ecole des Mines de Douai

Non-destructive testing techniques (NDT) are usually used for characterization of defects arising in composite materials during manufacturing or during in-service use. NDT techniques such as ultrasonic waves, X-ray radiography, X-ray tomography, infrared thermography, acoustic emission are the most commonly used in various industrial applications....

Non-destructive testing (NDT) techniques are usually used for the characterisation of defects arising in polymer composites during manufacturing or in-service use. However, each of these NDT techniques cannot always allow a full diagnosis of the material’s or component’s structural health. Thus, several techniques have to be combined in order to im...

This work presents a coupling between three multivariable analysis techniques (Principal Component Analysis (PCA), K-means and Kohonen Self-Organizing Map (KSOM)) applied to the acoustic emission data recorded on Glass Fiber-Reinforced Polymer (GFRP) composite materials in order to monitor and identify, in real-time, their damage mechanisms: matrix...

An inverse method for determining the in-plane effective thermal conductivity of porous thermoplastics was implemented by coupling infrared thermography experiments and numerical simulation of heat transfer in straight fins having temperature-dependent convective heat transfer coefficient. The microstructure heterogeneity of extruded polyethylene f...

Les matériaux aussi ont des problèmes de santé. Même les plus résistants comme les composites ne sont pas épargnés ! A leur naissance, lors de leur élaboration, ou plus tard au cours de leur vie en service, les composites organiques (plastiques renforcés par des fibres continues ou discontinues) peuvent être affectés de pathologies plus ou moins gr...

Au cœur des thématiques de l’Industrie du Futur, l’Intelligence Artificielle (IA) est un domaine de R&D en pleine expansion dans tous les secteurs, et notamment dans celui du monitoring de l’état de santé des matériaux et de la maintenance prédictive des structures et installations industrielles in-situ. Dans ce domaine d’application, le parallèle...

This paper focuses on the fatigue lifetime estimation of metallic components containing group of porosities as manufacturing defects. In order to represent these defects, six test specimens with different Side Drilled Holes (SDH) clusters, have been made of 7075-T6 aluminium alloy. Main characteristics of such defect (elementary size of porosities,...

Acoustic emission (AE) is a passive non-destructive testing (NDT) technique, which can detect evolving damage in materials or structures submitted to mechanical loading. Therefore, free stress structures cannot be monitored by AE. Moreover, there are numerous applications where mechanical loading stimulation is not desirable as it may induce damage...

Polymer composite materials are being increasingly used in primary load-bearing structures in several advanced industrial fields such as aerospace vessels, railway wagons and mega-scaled wind turbines where detection of subcritical damage initiation can significantly reduce safety issues and maintenance costs. It is therefore crucial to inspect the...

A hybrid non-destructive testing (NDT) approach has been developed for structural composites damage monitoring using several NDT techniques. Three nondestructive techniques (acoustic emission, infrared thermography and digital image correlation) were used simultaneously, in-situ and in real time to assess damage in an aeronautical carbon/epoxy comp...

An inverse method for determining the in-plane effective thermal conductivity of porous thermoplastics was implemented by coupling infrared thermography experiments and numerical solution of heat transfer in straight fins having temperature-dependent convective heat transfer coefficient. The obtained effective thermal conductivity values were compa...

In this paper, the mechanical behavior of semi-crystalline polymer films in finite elastoplastic strains is investigated. A 3-phase constitutive model has been specially developed in a previous paper and validated for various materials in both uniaxial and biaxial uniform hot drawing. In the present study, the numerical implementation of this 3-pha...

A hybrid non-destructive testing (NDT) approach has been developed to characterize composites damage using simultaneously bulk and guided ultrasonic waves, acoustic emission, and passive and active infrared thermography. Combining multiple NDT techniques makes it possible to optimize the diagnosis of a material's structural health.

The damage phenomenon occurring in glass fiber reinforced polymer (GFRP) laminate is very complex; it is inherently an anisotropic, multi-source and multi-scale process. In the present work, a new non destructive testing (NDT) approach is suggested using, simultaneously, multiple techniques. These are bulk and guided ultrasonic waves, acoustic emis...

The damage phenomenon occurring in glass fiber reinforced polymer (GFRP) laminate is very complex; it is inherently an anisotropic, multi-source and multi-scale process. In the present work, a new non destructive testing (NDT) approach is suggested using, simultaneously, multiple techniques. These are bulk and guided ultrasonic waves, acoustic emis...

A fracture mechanics approach (Essential Work of Fracture, EWF) was applied to assess the toughness of novel partly starch-grafted polyolefin blown films, compared to that of a neat polyethylene reference. Tests were performed on double-end notched samples. The digital image correlation method was used to monitor the deformation field around the no...

A method for simultaneous measurement of the thickness and density for Glass Fiber-Reinforced Polymer (GFRP) laminate plates with ultrasonic waves in C-Scan mode is presented in the form of maps. The method uses three different signals in immersion pulse-echo C-Scan mode. The maps obtained based on the density show the heterogeneity of the material...

The present work uses an active form of the infrared (IR) thermography technique for monitoring and characterization of the damage of glass fibers reinforced Polymer–Matrix Composites (PMCs) following an experimental protocol based on a monotonic tensile test with constant stress steps. The active form introduces a new approach using the cooling ra...

This work aims at establishing the effect of stress and temperature on the velocity of ultrasonic longitudinal waves in typical engineering polymers, and evaluating the potential of ultrasonic stress measurement in the evaluation of residual stresses in polymer parts. In order to estimate the effect of material morphology, two amorphous and two sem...

This study deals with characterization of the damage and thermomechanical behavior of the Glass Fiber-Reinforced Polymer composite materials (GFRP), submitted to static tensile loadings, using a passive infrared thermography technique. During mechanical testing, thermal measurements are performed by means of an IR camera. The thermal data post-proc...

In this study, Non-Destructive Testing (NDT) of the Polymer Composite Materials damage mechanisms by combining three techniques, namely ultrasonic waves, acoustic emission and infrared thermography was achieved. Longitudinal waves in C-scan representation were used to characterize the initial state of the tested materials, where high-resolution map...

The critically refracted longitudinal (L(CR)) wave can be used in numerous non-destructive testing (NDT) applications, such as characterization of surface geometric aspects, subsurface defect detection and mostly for residual stress measurement. However, very few works characterize the associated ultrasonic beam. This paper deals with characterizat...

In this study, Non-Destructive Testing (NDT) of the Polymer Composite Materials damage mechanisms by combining three techniques, namely ultrasonic waves, acoustic emission and infrared thermography was achieved. Longitudinal waves in C-scan representation were used to characterize initial state of the tested materials, where high resolution maps of...

At critical incidence, the critically refracted longitudinal (L CR) wave propagating in the subsurface domain of a solid specimen can be used in numerous non-destructive testing (NDT) applications, such as characterization of surface geometric aspects or structural subsurface properties of materials, like residual stress measurement. Generally spea...

The ultrasonic residual stresses measurement is based on the acoustoelastic effect that refers to the change in velocity of the elastic waves when propagating in a stressed media. The experimental method using the longitudinal critically refracted (Lcr) waves requires an acoustoelastic calibration and an accuracy measurement of the time-of-flight o...

In-situ health monitoring of the tensioning components such as strands, tendons, bars, anchorage bolts, etc. used in civil engineering structures, namely bridges, dams, nuclear power plants, etc. is extremely important to ensure security of users and environment. This paper deals with a guided ultrasonic wave procedure for monitoring the stress lev...

Acoustic Emission (AE) was investigated in order to monitor in real time the Mullins effect. Cyclic uniaxial tensile tests were carried out on two different natural rubbers. Different behaviour is revealed depending on whether or not the material undergoes the Mullins effect. The acoustic emission activity is very important during the first cycle,...

The safety of prestressed civil structures such as bridges, dams, nuclear power plants, etc. directly involves the security of both environment and users. Health monitoring of the tensioning components, such as strands, tendons, bars, anchorage bolts, etc. is an important research topic and a challenging task bringing together the non-destructive e...

In this paper, parameters for characterization of connected porosity and overall damage in the thermally-cracked rock of granite in order to assess, respectively, its transport properties and its mechanical strength are identified and quantified. Samples were heated to a range of peak temperatures up to 600 °C at ambient pressure. Characterizations...

The feasibility of an absolute ultrasonic measurement of the tightening force in bolts was investigated. For this purpose, we used both longitudinal and transverse ultrasonic waves (bi-wave method) to remove the time-of-flight measurement of waves in the unstressed state. To avoid the systematic calibration tests (generally carried out before tight...

The feasibility of an absolute ultrasonic measurement of the tightening force in bolts was investigated. For this purpose, we used both longitudinal and transverse ultrasonic waves (a biwave approach) to remove the time of flight measurement of waves in the unstressed state. First, we developed an equation based on the acoustoelasticity theory, whi...

Non destructive monitoring of prestressed civil structures such as bridges, dams, nuclear power plants, etc. is extremely important to ensure security of users and environment. This challenging task brings together the non destructive testing (NDT) and civil engineering (CE) communities. As a part of this relationship, this paper deals with a non d...