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This work presents a new multilayered laminated composite structure model to predict the mechanical behaviour of multilayered laminated composite structures.Thisnewmultilayered structure model describes the shear stress distribution model through the thickness respecting free boundary conditions on the top and bottom surfaces by an exponential function. This model has the same order of complexity as Touratier's model 'Sine', so a shear correction factor is not required like in the first-order shear deformation theory. This model is more precise than all other existing refined theories. This theory is based on the kinematic approach in which the shearing is represented by an exponential function. The virtual power principal is used to deduce the boundary value problem. To verify the precision of the present model, several significant problems on bending, vibration, and buckling of laminated and sandwich structures have been studied. The results by the present model are compared with the exact three-dimensional elasticity theory and with several other well-known theories. The proposed model is found to be more precise for analysing multilayered structures. [ABSTRACT FROM AUTHOR]

Spherical plain bearings are used on many components of Airbus aircrafts like engine-to-pylon and pylon-to-wing links. Their design is based on contact pressure distribution on spherical surfaces. Until now, empirical laws are applied to determine it, and the aim of this work is to develop a numerical modelling in order to validate the use of these laws. The assumptions on the numerical model and their significance have been verified and meas-ured by scattered light photoelasticity (SLP) on an epoxy replica of the bearing. The analysis of this type of bearing is difficult due to its three-dimensional behaviour and its spherical confined contact. The SLP technique allows getting information on stress fields inside an epoxy specimen with the analysis of photoelastic fringes. Comparing photoelastic fringes with simulated results, the finite-element model has been improved to be more representative of the real life bearing. In addition, some critical factors on the bearing behaviour have been obtained. [ABSTRACT FROM AUTHOR]

Long duration super-pressure balloon design and manufacturing is a great challenge for the Centre National d'Etudes Spatiales in scientific ballooning. They are made of 50 μm thick polymer films polyethylene terephtalate/polyamide/polyethylene terephtalate which are joined with 23 μm thick adhesive polyethylene terephtalate bands. To date, during flight missions, a major problem appears: some balloons explode prematurely. This is why this study deals with the mechanical behaviour of the stratospheric pressurized balloons and particularly with the assembly of the constitutive films material. First, a nanoindentation test campaign makes it possible to identify the elastic properties of the materials at two different temperatures. Then, a nominal assembly is simulated in two stages: two-dimensional and three-dimensional. Finally, the factorial design method combined with finite-element simulations was used to study the influence of the various conception parameters on the mechanical behaviour of the assembly. [ABSTRACT FROM AUTHOR]

Abstract: On Airbus aircraft, spherical plain bearings are used on many components; in particular to link engine to pylon or pylon to wing. Design of bearings is based on contact pressure distribution on spherical surfaces. To determine this distribution, a 3D analysis of the mechanical behaviour of aeronautical plain bearing is presented in this paper. A numerical model has been built and validated from a comparison with 3D experimental measurements of kinematic components. For that, digital volume correlation (DVC) coupled with optical scanning tomography (OST) is employed to study the mechanical response of a plain bearing model made in epoxy resin. Experimental results have been compared with the ones obtained from the simulated model. This comparison enables us to study the influence of various boundary conditions to build the FE model. Some factors have been highlighted like the fitting behaviour which can radically change contact pressure distribution. This work shows the contribution of a representative mechanical environment to study precisely mechanical response of aeronautical plain bearings. [Copyright &y& Elsevier]

Abstract: One of the current problems connected with multi-layer composite structures concerns the analysis of the distribution of the stresses around peculiarities (free edge and loaded edge) and at the interfaces of each layer. This work presents a new shear stress function in the form of the exponential function, to predict the mechanical behaviour of multi-layered laminated composite structures. As a case study, the mechanical behaviour of a laminated composite beam (90°/0°/0°/90°) is examined. The results are compared with the model “Sinus” and 2D finite element method studied. Results show that this new model is more precise than older ones as compared to the results obtained by the finite element analysis [Abaqus]. To introduce continuity on the interfaces of each layer, the kinematics defined by Ossadzow is used with the new exponential model. The equilibrium equations and natural boundary conditions are derived by the principle of virtual power. [Copyright &y& Elsevier]