-significantly different Poisson ratios between the fibre direction/perpendicular-to-the-fibre direction and the two perpendiculars to the fibre directions; -ply thicknesses between 30 and 70 μm.A constitutive anisotropic elasto-plastic law for this class of materials is proposed, and its validity with reference to Tensylon™ is verified experimentally. Satisfactory agreement is reached, and the viscous nature of the deviations between the model proposed and the experimental results is revealed.

The paper purpose is to present some aspects regarding the calculus model and technical solutions for small satellites attitude control. Mathematical model is put in nonlinear and linear form. The linear form is used for attitude control system synthesis. The attitude control system obtained is used in nonlinear form in order to maintain desired attitude. A few numerical simulations are made for standard input and the satellite behavior is obtained. The satellite model presented will be with six DOF and use Cartesian coordinates. At this item, as novelty of the work we will use the rotation angles to describe the kinematical equations. Also this paper proposes a Fourier linearising of Trigger Schmidt element used for applying the command moment. The results analyzed will be the rotation angles of the satellite as well the rotation velocity. The conclusions will focus the comparison between results obtained using optimal attitude control system, and the possibility to use such system for small satellite.

Abstract. This study refers to an experimental and numerical evaluation of a polyurea coating layer influence on the dynamic behaviour of OL50 specimens. Mechanical quasi-static and dynamic tensile tests were performed in axial loading conditions, for 2 mm steel plate specimens. Several metallic specimens have been previously coated with 1.5 mm and 3 mm respectively thickness polyurea layer and tested in traction. The findings results indicate that the presence of polyurea changes the loading pattern of metallic material in the necking area. In terms of polyurea coated metal specimens fracture, there was clearly observed a change of fracture limit. One possible explanation of this phenomenon is the modification of triaxiality state in the necking zone, fact proven by the numerical simulations. Test results indicate that the presence of polyurea layer delays the necking onset phenomenon which precedes the OL50 metallic specimen fracture.

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