Damage mechanisms assessment of hybrid carbon/flax fibre composites using acoustic emission

The purpose of the present experimental study is to describe the damage mechanisms occurring in epoxy matrix composites reinforced with hybrid carbon-flax fibres. The samples tested were consist of unidirectional carbon and flax fibre plies with different stacking sequences. Composite laminates were manufactured by hand lay-up process. The specimens were tested under uniaxial tensile loading. The tests carried out were monitored by the acoustic emission (AE) technique. The results obtained during the monotonic tensile tests were analyzed in order to identify the damage mechanisms evolutions. The recorded events were classified with the k-means algorithm which is a statistical multivariable analysis. In addition, it was an unsupervised classification according to temporal descriptors. The percentage of each damage mechanism to the global failure was evaluated by the hits number and the acoustic energy activity. The AE technique was correlated with scanning electron microscopy (SEM) observations to identify the typical damage mechanisms

Effet de l'hybridation sur les propriétés mécaniques et vibratoires des composites à fibres lin-carbone

International audienceIn recent days, several industries are focus on the light weight and environmentallyfriendly materials with good mechanical and damping properties.Flax fiber reinforced composites have been proven in the field of dynamics with high vibration damping performance. Nevertheless, their static mechanical and fatigue characteristics are much less important than composites made of carbon fibers.To overcome these problems, hybridization technique of flax fibers and carbon fibers is used to manufacture compositesto enhance their properties.Therefore, the objective of this study is to investigate the effect of hybridization on the mechanical and vibratory behavior of composites.Two types of non-hybrid laminates (flax / epoxy and carbon / epoxy) and different hybrid laminates (flax / carbon / epoxy) have been experimentally characterized. At first, the different composite laminates were studied using uni-axial tensile tests. In a second step, an experimental modal analysis was conducted to identify the damping coefficients experimentally.Ces derniers jours, plusieurs industries se sont concentrées sur les matériaux légers et écologiques, dotés de bonnes propriétés mécaniques et amortissantes.Les composites renforcés de fibres de lin ont fait leur preuve dans le domaine de la dynamique en présentant des performances élevées en amortissement des vibrations. Néanmoins, leurs caractéristiques mécaniques statiques et de fatigue sont nettement moins importantes que celles des composites constitués de fibres de carbone. Pour surmonter ces problèmes, la technique d'hybridation de fibres de lin et de fibres de carbone est utilisée pour fabriquer les composites afin d’améliorer leurs propriétés.De ce fait, l’objectif de la présente étude consiste à investiguer l’effet de l’hybridation sur le comportement mécanique et vibratoire des composites. Deux types de stratifiés non-hybride (lin/époxy et carbone/époxy) et différentes stratifiés hybrides (lin/carbone/époxy) ont été caractérisés expérimentalement.Dans un premier temps, les différents stratifiés composites ont été étudiés à l'aide des essais de traction uni-axiaux. Dans un deuxième temps, une analyse modale expérimentale a été menée afin d’identifier expérimentalement les coefficients d’amortissemen

International Conference on Acoustics and Vibration

The book provides readers with a snapshot of recent research and industrial trends in field of industrial acoustics and vibration. Each chapter, accepted after a rigorous peer-review process, reports on a selected, original piece of work presented and discussed at International Conference on Acoustics and Vibration (ICAV2016), which was organized by the Tunisian Association of Industrial Acoustics and Vibration (ATAVI) and held March 21-23, in Hammamet, Tunisia. The contributions, mainly written by north African authors, covers advances in both theory and practice in a variety of subfields, such as: smart materials and structures; fluid-structure interaction; structural acoustics as well as computational vibro-acoustics and numerical methods. Further topics include: engines control, noise identification, robust design, flow-induced vibration and many others.This book provides a valuable resource for both academics and professionals dealing with diverse issues in applied mechanics. By combining advanced theories with industrial issues, it is expected to facilitate communication and collaboration between different groups of researchers and technology users