Reversible Rail Shear Apparatus Applied to the Study of Woven Laminate Shear Behavior

The multitude of in-plane shear tests existing in the literature seems to demonstrate the complexity of developing a test adapted to all experimental works. In a general framework of investigation of translaminar cracks in thin laminates, a test able to reproduce a pure in-plane shear loading was required. The laminate studied is notably employed as helicopter blade skin, and cyclic torsion induced by aerodynamic load involves cyclic in-plane shear. This particular application established some specifications for the test needed to carry out this study. To comply with them, an original technological solution has been developed from a three-rail shear test apparatus. This paper describes the resulting “reversible rail shear test” solution and its application to the study of in-plane shear behavior of a thin glass-epoxy laminate. The results concern plain and notched coupons under quasi-static loading, and crack growth tests under cyclic loading

Multi-method characterization of soda-lime glass corrosion : Part 2. Corrosion in humidity Report of the International Commissionon Glass (ICG) Subcommittee of Technical Committee 19 "Glass Surface Diagnostics"

As-received and cleaned soda-lime glass surfaces corroded in high relative humidity of 95 % at a temperature of 60 °C for times up to one week are investigated by means of TOF-SIMS, SNMS, XPS, NRA, ERD, RBS, GIXR, AFM, SEM and optical microscopy. Distinct differences in the corrosion behavior are observed for as-received and cleaned glass surfaces. Changes in element concentration in the glass interface and in the topography of the glass surfaces are described for different exposure times in humidity. They are combined with variations in density of the modified surface layer. Cleaning before the corrosion treatment drastically reduces degradation; cleaning after the corrosion treatment can restore the surface

Propagation de coupure dans des tissus de verre de pâles arrières d'hélicoptères

L'objet de ce travail est l'étude de la propagation de coupure en fatigue dans des tissus composites de verre/époxy utilisés pour la fabrication de pâles arrières d'hélicoptères par la société EUROCOPTER. Une étude des directions chaîne et trame du tissu a été menée et a montré une différence de comportement importante sur la vitesse de propagation d'une coupure; en particulier le temps d'initiation dans la direction trame s'est révélé près de 10 fois plus important que celui de la chaine

Semi-continuous approach for the modeling of thin woven composite panels applied to oblique impacts on helicopter blades

International audienceIn aeronautics, passenger safety and reliability of structures are essential aspects. In the specific case of helicopters, blades are subjected to impact loadings. Modeling these phenomena continue to be difficult and experimental tests often replace the prediction. The following work will focus on the experimental and numerical study of an oblique impact on the skin of the blade. It is equivalent in a first approach to an impact on a sandwich panel made up of a foam core and a thin woven composite skin. The objectives are to identify the mechanisms of damage in the skin for this kind of loading and to develop a representative modeling of the chronology of damage adapted to the modeling of the complete structure. Thus, a semi-continuous F.E. explicit modeling has been developed. It relies on the development of a specific damageable element at the bundles scale. Satisfactory numerical results are obtained. They allow the identification of the damage mechanism of the woven skin

Experimental and numerical study of oblique impact on woven composite sandwich structure: Influence of the firing axis orientation

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Light coupling with a nonlinear prism

International audienceWe propose the use of a prism with nonlinear optical properties to improve the prism-coupling method. The principle is based on the inscription of an adapted waveguide inside this prism by beam self-trapping to enhance the coupling efficiency and stability. The experimental demonstration is realized with a prism diced from a LiNbO3 wafer to couple light into a resonator

Experimental and Numerical Study of Normal and Oblique Impacts on Helicopter Blades

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Semi-continuous approach for the study of impacts on woven composite laminates: Modeling interlaminar behavior with a specific interface element

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Multi-method characterization of soda-lime glass corrosion : Part 1. Analysis techniques and corrosion in liquid water Report of the International Commission on Glass (ICG) Subcommittee of Technical Committee 19 "Glass Surface Diagnostics"

Corroded soda-lime float glass surfaces prepared in water (room temperature and 60 °C) or air (relative humidity of 95 %, 60 °C) for different times are invesdgated by means of SIMS, SNMS, XPS, NRA, ERD, RBS, GIXR, AFM, SEM, light microscopy and scratch testing. The corrosion effects are studied for as-received and cleaned glass surfaces. Changes in the dement concentration in the glass interfaces with the immersion time in water are described. They are combined with variations in density of the surface layer which exhibits plastic deformation behaviour. Inhomogeneous corrosion leads to changes in the topography and an increase in surface roughness