AETECH - Acoustic Emission Technology

Caractérisation par émission acoustique de l'adhérence et de l'endommagement d'un revêtement : cas d'un revêtement WC–Co sur acier

30/05/2003

Cette note présente une méthode de caractérisation par émission acoustique de « l'adhérence » d'un revêtement sur son substrat. Lors de tests de flexion quatre points, des mesures in situ de l'émission acoustique, exploitées en termes d'amplitude, d'énergie absolue et de position des événements... ont été réalisées sur des éprouvettes revêtues de cermet WC–Co par HVOF (High Velocity Oxy Fuel). L'observation microscopique des éprouvettes a mis en évidence la présence de deux types de fissuration : une fissuration transverse (fissures régulièrement espacées à la surface) et une fissuration interfaciale (délaminage). Les résultats d'émission acoustique ont révélé deux types différents d'événements (en termes d'amplitudes et d'énergies), représentatifs des deux modes de fissuration observés.

Davy Dalmas, Salim Benmedakhene, Caroline Richard, Abdelouahed Laksimi, Gérard Béranger and Thierry Grégoire

Publication complète

Damage analysis and the fibre–matrix effect in polypropylene reinforced by short glass fibres above glass transition temperature

17/01/2003

In this paper an experimental and theoretic study of the influence of the fibre–matrix interface on the damage of the polypropylene reinforced with 40% in mass of short glass fibres is described. Tensile tests show the existence of several zones of behaviour, which are linear, non-linear without damage and non-linear with damage for material with treated and untreated short glass fibres. Creep tests with damage were carried out on each material. The number of acoustic emission events characterizing each damage mechanism, is more significant for the material with treated fibres. Also, the kinetics of damage is more pronounced in the first phase of damage for material with untreated fibres.

E. Ségard, S. Benmedakhene, A. Laksimi and D. Laï

Publication complète

Influence of the fibre–matrix interface on the behaviour of polypropylene reinforced by short glass fibres above glass transition temperature

07/08/2002

This paper describes an experimental and theoretic study of the influence of the fibre–matrix interface on the behaviour of the polypropylene reinforced with 40% in mass of short glass fibres. Tensile tests show that three zones of behaviour, which are linear, non-linear without damage and non-linear with damage, exist for each material tested. Creep-recovery tests without damage were carried out on the polypropylene reinforced with treated and untreated short glass fibres. Five stress levels were used for the creep tests according to the three zones determined with the tensile tests. The creep-recovery tests show the presence of elasticity, viscoelasticity (linear and non-linear) and viscoplasticity. The elasticity and viscoelasticity are described by Schapery's nonlinear constitutive equation and the viscoplasticity by Zapas–Crissman's equation. The results show that the elastic, viscoelastic and viscoplastic strains are more significant for the materials with untreated fibres.

E. Ségard, S Benmedakhene, A. Laksimi and D. Laï

Publication complète

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