Experimental Study of Mechanical Behaviour of Renewable Fibre Reinforced Composite Materials Type (Cynara Cardunculus L/Polyester)

International audienceThis study is particularly focused on renewable materials of bio-composites. Our work draws on the extraction method and the mechanical characterisation of natural fibres of artichokes (Cyanara cardunculus L) which are produced naturally and in abundance in the northern regions of Algeria particularly so in the north-east. It also draws on the manufacturing of composite with bio-reinforcement models consisting of long fibres of laminated materials of the Cyanara cardunculus L type compiled with unsaturated polyester resin. Standardised sample test-pieces are then drawn from these models so as to carry out tensile and shear tests to evaluate their mechanical behaviour. Additionally, the diversity in characteristics necessitates the use of statistical approaches in order to estimate the proper Weibull parameters of natural fibres, based on a Weibull distribution

Experimental in-plane characterization of a cellular material composed by a cell with a normal re-entrant link and geometrical parameters effects on the structure mechanical properties

International audienceIn this work, we have characterized a cellular structure constituted by a new cell on which we carried out, initially, tensile and shear tests in order to get its in-plane mechanical properties; in the second time, we explored the effects that geometry will have on these mechanical properties by varying the geometric parameters of the cell. The specimens were designed by Computer Aided Design software and obtained by rapid prototyping (laser cutting). In the quest for results, we used the technique of marker tracking. This optical method of correlating images consists in measuring the plane components of the displacement of a plane surface leaving some marks on the specimen. This makes it possible to determine the in-plane components of the transformation gradient tensor and to reach the plane components of the deformation tensor under certain assumptions (axisymmetric or isochoric transformation, small deformations, etc). The material of the studied structure is a polymethylmethacrylate, often abbreviated to PMMA. The first results gave a negative Poisson's ratio, announcing an auxetic behavior. The following results have confirmed the auxetic character of the cell and show great influence of the geometric parameters on the mechanical properties of the new structure