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Vers une maîtrise des incertitudes en calculs des structures composites

Abstract : Security requirements in the aeronautic field require to take account of the various uncertainties affecting the structures, in particular the material variability. Despite their expansion, numerical simulations consider most of the time this topic in a simplify way, for example applying penalty to the material properties used in the calculations. But the increasing use of composite materials, intrinsically more sensitive to uncertainties, necessitates the development of sharper methods that could insure a better reliability of the design. Thus, the new Variability Analysis approach has been developed, to deal with numerical simulations constraints, such as computational code independence and limited number of calculations. Choice has been made to build an approach using response surface techniques. This approach is progressive for a better use of the various type of approximation selected (polynomials, polynomial chaos, kriging). Cross-validation techniques (leave-k-out, bootstrap) have been used to estimate the quality of the approximation. So that it is possible to display an assessment of the effects of uncertainties (with error bars) but also to evaluate the confidence of this assessment. Mathematical and analytic mechanical examples have permitted the validation of the approach which shows good agreements with Monte-Carlo simulations for a lower computation cost. Uncertain parameters used concern as well the geometry or the material properties as specific composite parameters (orientation and thickness of plies). Applied on various examples of finite elements calculations, the approach has shown good performances and a reasonable computing cost. Finally, the question of the reduction of the uncertainties effects has been considered. Solutions such as reduction of the uncertainties on the given parameters or improvement of models were investigated. In the end the new data basis improvement method, using correlation between parameters at the various scaled of composite materials, has been proposed.
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Submitted on : Tuesday, February 19, 2008 - 11:19:10 AM
Last modification on : Monday, October 19, 2020 - 10:59:42 AM
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  • HAL Id : tel-00257371, version 1



Yannis Rollet. Vers une maîtrise des incertitudes en calculs des structures composites. Mécanique []. Ecole Polytechnique X, 2007. Français. ⟨tel-00257371⟩



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