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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 33

Efficient Reliability-Based Design Optimization of Structural-Acoustic Problems

A. Mohsine and A. El-Hami

INSA de Rouen, LMR, St Etienne du Rouvray, France

Full Bibliographic Reference for this paper
A. Mohsine, A. El-Hami, "Efficient Reliability-Based Design Optimization of Structural-Acoustic Problems", 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 33, 2006. doi:10.4203/ccp.83.33
Keywords: reliability-based design optimization, structural reliability, acoustic, probabilistic model.

Summary
The objective of reliability based design optimization (RBDO), it is to provide the designer with structures that should be economic and reliable. The RBDO problem is often formulated as a minimization of the initial structural cost under constraints imposed on the values of elemental reliability indices corresponding to various limit states. The classical RBDO leads to high computing time and weak convergence. To overcome these two drawbacks, a hybrid method has been elaborated [1]. It has been demonstrated that the hybrid method successfully reduces the computing time in static and dynamic cases [1]. The formulation of the hybrid method is expressed by:

   

In this formulation, is the distance in the hybrid space between the optimum solution and the design point (the most probable failure point). The minimization of the total function is carried out in the hybrid design space (HDS) of deterministic variables and random variables . In the above formulation the deterministic variable vector is found in both functions: and but the random vector is only located in the distance function . Therefore, when minimizing the total objective function , we may obtain several optimum solutions verifying the different constraints of the problem, especially the reliability index constraint. In order to obtain a global solution, we propose in this paper, to multiply the objective function with the random vector by the total objective function. So, the formulation of the improved hybrid method can be expressed as:

   

Using the proposed formulation, we can improve our results (objective function) and we can control the optimal configuration of the studied structure to get global solution. A numerical application shows the importance of the improved hybrid method.

In this paper, we apply the improved hybrid method as an efficient RBDO approach to the acoustic problem.

References
1
Kharmanda, G., Mohamed, A. and Lemaire, M. "Efficient reliability-based design optimization using a hybrid space with application to finite element analysis", Struct. Multidisc. Optim 24 3, pp 233-245, 2002. doi:10.1007/s00158-002-0233-z

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