Experimental investigation of the mechanical behavior of glass fiber/high fluidity polyamide-based composites for automotive market

International audienceIn this work, we examine the relationships between the microstructure and the mechanical properties of glass fiber–reinforced polyamide 6,6 composite materials ( V f = 54%). These materials made by thermocompression incorporate different grades of high fluidity polyamide-based polymers and two types of quasi-UD glass fiber reinforcement. One is a classic commercial fabric, while the other specially designed and manufactured incorporates weaker tex glass yarns (the spacer) to increase the planar permeability of the preform. The effects of the viscosity of the polymers and their composition on the wettability of the reinforcements were analyzed by scanning electron microscopy observations of the microstructure. The respective influences of the polymers and the spacer on the mechanical performance were determined by uniaxial tensile and compression tests in the directions parallel and transverse to the warp yarns. Not only does the spacer enhance permeability but it also improves physical and mechanical properties: tensile longitudinal Young’s modulus increased from 38.2 GPa to 42.9 GPa (13% growth), tensile strength increased from 618.9 MPa to 697 MPa (3% growth), and decrease in ultimate strain from 1.8% to 1.7% (5% reduction). The correlation of these results with the damage observed post mortem confirms those acquired from analyses of the microstructure of composites and the rheological behaviors of polymers

Behavior of Composite Instrumented by Optical Fiber

International audienc

Identification à l'aide de capteurs optiques à réseaux de Bragg des coefficients de dilatation hygroscopiques d'un composite à matrice organique

Cette étude porte sur l'identification des coefficients de dilatation hygroscopique de matériaux composites au moyen d'une nouvelle technique de mesure. Celle-ci repose sur l'insertion de capteurs optiques à réseaux de Bragg au coeur de la structure composite. Cette méthode est dédiée à la mesure de la déformation hygroscopique induite par la diffusion d'humidité dans un composite. L'évolution de la déformation, due à l'absorption d'humidité, a été représentée en fonction de la teneur en eau, afin de caractériser le coefficient de dilatation hygroscopique

Numerical end experimental investigation of hygro mechanical states of glass fiber reinforced polyester composites experienced by FBG sensors

International audienceThis study is focused on the finite element analysis of the hygro-elastic stresses experienced by unidirectional composite structures instrumented by Fiber Bragg Grating (FBG) sensors. One of the significant advantages of this method is that by taking into account the complex geometry of elaborated specimen and their different constituents with heterogeneous hygroscopic and mechanical properties. In the first time, the obtained results were compared with the results obtained owing to an analytical solution deduced from the simplified concentric cylinders approach. This comparison allows us to evaluate the reliability of the concentric cylinders approach which cannot account for every aspects of the actual geometry of the studied samples. Besides the numerical results were compared to the experimental characterization of the mechanical states deduced from the Fiber Bragg Grating measurements

Polymer additive manufacturing of ABS structure: Influence of printing direction on mechanical properties

International audienceThe present study relates to Polymers Additive Manufacturing (PAM) traditionally used for rapid prototyping operations. The use of PAM components as functional parts is still marginal compared to injection molded components. This is due to the uncertainty on their mechanical properties and to the present knowledge on PAM products. A new additive manufacturing technology has been integrated in the free former-Arburg machine. It was inspired by injection molding technology and creates plastic parts using layers built up from tiny droplets of polymer. In this work, the mechanical characterization of thermoplastic polymer parts obtained by Arburg Plastic Free forming (APF) is studied. Additionally the mechanical properties of polymer specimens obtained by injection molding as a conventional process are studied in order to evaluate the influence of the manufacturing process on the parts mechanical behavior. The tensile mechanical properties are evaluated by varying some manufacturing parameters, such as the printing path. Microstructural analyses have been performed to better understand the relationship between the manufacturing process and the final mechanical properties

Durabilité des matériaux composites sous sollicitations hygrothermomécaniques

International audienceThe scope of the paper is to present the key points to be addressed in a durability study in the case composite materials in hygrothermomechanical environments. The experimental aging tests allowing the identificat ion of the diffusive behavior are presented. The induced effects on the mechanical behavior and the hygrothermomechanical coupling phenomenon are also examined.L’objectif de cet article est de présenter les points-clés d’une étude de durabilité pour des matériaux composites soumis à un environnement hygrothermomécanique. La démarche permettant de réaliser des essais de vieillissement afin d’identifier le comportement diffusif est présentée. Les effets induits sur le comportement mécanique et les phénomènes de couplages hygrothermomécaniques sont ensuite examinés