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This paper presents the properties of the high- density polyethylene based hybrid composite made with two natural fibers: chicken feather and sawdust. The composites were produced and fabricated with the aid of two processes they are extrusion and injection molding. These composites were produced with different chicken feather and sawdust ratios (80H-10CF-10SD, 80H-5CF-15SD, and 80H-15CF-5SD). Tensile and Flexural tests were performed using a Universal Testing Machine (UTM) and impact strength was tested with notched Izod impact test method. Results showed that there is an improvement in the different mechanical properties such as tensile, flexural and impact strength because of the addition of chicken feather and sawdust. [ABSTRACT FROM AUTHOR]

The presence of the elliptical holes may lead to the increase in local stress, this phenomenon is known as stress concentration, has dangerous consequences what causes damage to the metal or composite structures. In this analytical and numerical study outlines the effect of the presence of elliptical hole on the mechanical behavior of composite structures. This is to determine the stress distribution around and away from the hole under pure tensile stress. The study focused on the evaluation of the stress concentration factor that is considered as an inducer of the local increase in stress due to the presence of the hole. This factor has been studied as a function of some parameters such as the variation of elliptical ratio (a/b) and the tensile stress of angles to the direction of large axis of the ellipse b (°/), and the variation of the fiber orientation. [ABSTRACT FROM AUTHOR]

Adhesive material is one of the main and fragile component in wind turbine blades. Being large in size compared to the conventional ones, the wind turbine blades are manufactured with composite materials. Generally blades are made by upper and lower sections separately and are joined together by adhesive materials. New generation wind turbines with an increased blade length makes the assembly procedure complicated for the blade manufacturers. Also the adhesive material failure is dependent on the rate of stress transfer between composite and adhesive materials. So, it becomes essential to study the bonding failure both in local and global scale of wind turbine blades. In this paper, we discuss an influence of lay-up orientation of the composite material on the failure of adhesive material used in wind turbine model for macro-scale and single-lap-joint model for meso-scale study. [ABSTRACT FROM AUTHOR]

The drilling circular holes in composite materials is necessary for mechanical purposes such as reducing the moment of inertia of the disks and assembly of parts and energy needs as the evacuation of heat in cooling systems. Precedence holes in composite structures causes the stress concentration phenomen on which negatively affects their mechanical behavior. This behavior is analyzed by a factor, said stress concentration factor (SCF), which expresses the maximum local variation of the stress due to the presence of the hole. In this study two analytical approaches were considered to evaluate this stress concentration factor in the plates with holes in composite materials, namely Lekhnitskii theory (1968) and the Green-Zerna (1954). The plates are loaded in pure tension and pure compression. The results will be compared with those calculated by the finite element method for different fiber orientation angles. [ABSTRACT FROM AUTHOR]

This paper presents the works performed by Airbus Group Innovations (AGI) within the ANR VULCOMP project achieved on 2010. They are on the intra-laminar damages of composite materials under static and dynamic loads and a new method of damage identification from monotonous tests. The studied material is the UD carbon tape T700/M21. The main part of these works is focused on the dynamic tests up to a nominal strain rate between 150 /s and 200 /s. Three tendencies are observed about the shear damage in the plane of the UD tape, compared to the static reference. The first one is an increase of the damage threshold as a function of the strain rate. The second one concerns the damage progression by steps: no progression when strain rate strongly increases, progression when strain rate decreases. The third one is that the damage level is lower than in the static case. [ABSTRACT FROM AUTHOR]

The precedence of geometrical singularities like holes in substructures is a technological need for mechanical requirements such as assembly and pipes. The presence of holes can lead to a weakening of the structure, as a consequence of the increase in the local stress. This phenomenon, known as stress concentration, causes damage to the metallic or composite structures and affects negatively their safety. In this analytical and numerical study, the effect of the presence of a circular hole on the mechanical behavior of orthotropic plate is considered. This is to determine the stress distribution around and away from the hole under pure traction. The study focused on determining the stress concentration factor which is considered as an inducer of the local increase of the stress due to the presence of the hole. A parametric study was also undertaken to highlight the effect of some parameter such as hole size, fiber orientation, layers stratification, the anisotropy ratio, and loading type. [ABSTRACT FROM AUTHOR]