![]() |
Computational & Technology Resources
an online resource for computational,
engineering & technology publications |
Civil-Comp Proceedings
ISSN 1759-3433 CCP: 83
PROCEEDINGS OF THE EIGHTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping, G. Montero and R. Montenegro
Paper 48
Reliability and Optimization of a Fully Composite Stiffened Cylinder M. Olivier-Mailhé1, S. Ben Chaabane1, F. Léné2, G. Duvaut1 and S. Grihon3
1ESILV Dep MS, PULV, Paris, France
Full Bibliographic Reference for this paper
, "Reliability and Optimization of a Fully Composite Stiffened Cylinder", in B.H.V. Topping, G. Montero, R. Montenegro, (Editors), "Proceedings of the Eighth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 48, 2006. doi:10.4203/ccp.83.48
Keywords: composite material, reliability, optimization, finite elements.
Summary
Due to their high stiffness and low mass, composite materials take more and more
importance in the design of plane structures (e.g. wings, tails). Their extension to the
design of fully composite fuselage is under development.
The great increase in computer performance contributes to the generalization and to the intensive use of optimization methods and their application to composite structures. However these optimization methods lead to deterministic optimum designs, and don't include the variability of the design parameters. These configurations ignoring the different uncertainties can result in unreliable designs. The origin of uncertainties can be for example geometrical, modeling, simulation or manufacturing.
Several authors recently addressed these uncertainties. Moreover the reliability
studies taking into account the uncertainties were often coupled with optimization
strategies, leading to the Reliability Based Design Optimization methods (RBDO).
Many studies use the reliability index Firstly we perform a sensitivity analysis with some parameters (e.g. material parameters, geometrical parameters). The number, position and geometry of the longitudinal stiffeners appear to be the more influential parameters and are considered in the further calculations. The continuous parameters are supposed to be uncertain with a normal distribution. In order to be consistent with the manufacturing process and to limit the number of parameters, we define four zones in the fuselage. The stiffeners have the same profile in all the zones.
The objective of the optimization problem is to set the failure probability lower than
an acceptable value
The algorithm consists of three steps:
All the optimization and statistical analysis are computed on the response surface obtained by a Latin Hypercube Sampling and quadratic approximation. The Monte-Carlo simulation and the optimization are immediate as the approximate function is analytically defined. The methodology proposed provides good results. the first critical load is improved by almost 20%, when the mass increases by only 2.2%. The failure probability of the optimized structure is acceptable (0.125%) and the influence of each zone of the cylinder section is established. The work developed in this paper is a practical way to reach a reliable objective for the buckling behavior of such structures without enormous calculation cost nor increase of the mass. purchase the full-text of this paper (price £20)
go to the previous paper |
|