Conception, modélisation, fabrication et validation expérimentale d'une structure d'aile en matériaux composites

Abstract

This work is a result of the project CRIAQ 7.1 which goal was: "to improve the laminar flow of an aeroelastic wing" [1]. The development of a prototype of a wing with the upper section of adaptive was the result. This flexible composite section was attached to a solid aluminum base. This work focuses on the design of a composite structure at can replace the aluminum base of the project CRIAQ 7.1. A finite element analysis model is developed and experimentally validated to allow the prediction of the displacement of the structure under different static loads. A first investigation of the manufacturing process, vacuum assisted infusion (VARTM), is carried out using the analysis of the percentage by volume of fiber (ASTM 3171) and air (ASTM 2734) of 131 samples from 13 different composites panels. The composites used are the T300 Twill 2x2/8604 and T300 Twill Unidirectional/8604. Respective values of 65% and 59% for the percentage of fiber and 0.3% and 1.4% for the porosity with standard deviations for all values less than 1% have concluded that the process is stable and that the future part produced will present similar mechanical properties. The mechanical properties are then obtained using tension tests performed according to ASTM D 3039 and ASTM D 3515. An easily manufacturable structure formed of two spars, height ribs and an upper and a lower surface is selected as the starting point for design. The scale is set at two meters and CATIAV5 is used for 3D modeling of the structure. Subsequently, a step on the comparison between the experimental and numerical results of 217 rectangular specimens subjected to loads in tension and bending allowed the validation of a first simple numerical model and the prediction of the sources of error of future models much complex. A first EF model of the simplified structure is then used to determine the positions of the spars so as to optimize the flexural and torsional rigidity of the section. This step is necessary to set the center of gravity of the structure, this value being useful to the calculation of aerodynamic forces. The software Ansys Classic and an APDL code are used for all EF analyzes. The aerodynamic loads are determined using lift profiles of wind tunnel values obtained during the project CRIAQ 7.1. The lift force and the torque generated by the distance between the center of gravity and the aerodynamic load center are calculated for the 35 flight conditions tested experimentally in the project CRIAQ 7.1. The maximum values of 3590 kN for the lift force and 295 Nm for the torque are used when designing laminates. An optimization criterion called the Laminate Structural Optimization Factor (LSOF) is then developed to allow comparison of several laminates subjected to loads in tension and shear respectively generated by the bending and twisting of the structure. Matlab software is then used to program an algorithm for calculating the IOSS criterion and the Tsai-Wu (TW) failure criterion for different stacks at the upper and lower surfaces of the structure. In total, 59 385 laminated are compared to allow the setting to six of the number of plies for the first EF analysis. The FE model of the simplified structure is reused for the final optimization of the orientation of the plies of the intrados and the extrados. Finally, an buckling analysis of the upper surface is carried out to determine the number of ribs. The addition of an ply allowed to fix the critical buckling length to 250 mm with a safety factor (SF) of 2. A FE model of the complete structure is then developed for the final analyzes of the structure and the comparison of the displacements that will be obtained during experimental testing. The final FE model includes all components of the structure, the bonding joints and the changes made to the model to allow static loading. A prototype of the structure is then fabricated and tested. Plugs are first modeled for all components and machined using a machining center for wood. Polyester and glass fiber molds are then produced using the machined plugs. These molds are then used for infusion (VARTM) of all the components. A jig is finally used for the bonding of the internal structure, the upper surface, the lower surface and the attachment points for the loads. For the experimental tests, the structure of the wing is fixed at one end with the upper surface pointing towards the ground. Three different loads are applied using sandbag. Finally, an adjustment of the axial stiffness of the unidirectional composite (128 GPa to 118 GPa) for the numerical model has to reproduce the observed flexion displacement during static load tests with a error percentage less than 2%.

Date	9 May 2012
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Vladimir Brailovski (Supervisor) & Patrick Terriault (Co-supervisor)