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Pagnacco E.,CNRS Optimisation and Reliability in Structural Mechanics lab | Zidani H.,Mohammed V University | Sampaio R.,Pontifical Catholic University of Rio de Janeiro | de Cursi E.S.,CNRS Optimisation and Reliability in Structural Mechanics lab | Ellaia R.,Mohammed V University
Latin American Journal of Solids and Structures | Year: 2016

This work deals with the design of a suspension device, idealized as a spring-mass-damper system. The amplitude of a nominal system is constrained to satisfy certain limitations in a given frequency band and the design is to be done as a reliability-based optimization. This constitutes a major difficulty since the constraint becomes a random process. To concentrate in the main ideas, only the stiffness of the system will be considered random. The stiffness is characterized by a uniform random variable, and its mean and standard deviation are the optimization parameters. The design problem is stated as a two-objective optimization. They are the mean and the standard deviation of the stiffness: one search for the lowest stiffness and the greatest standard deviation, while the amplitude response must be within the acceptable domain of vibration, which is prescribed. To generate the Pareto front, the Normal Boundary Intersection method is used in the RFNM algorithm. Results show that a not-connected Pareto curve can be obtained for some choice of constraint. Hence, in this simple example, one shows that difficult situations can occur in the design of dynamic systems when prescribing an amplitude-response hull. Despite the simplicity of the example treated here, chosen to highlight the main ideas without distraction, the strategy proposed here can be generalized for more complex cases and give valuable results, able to help designers to choose for the best compromise between the mean and the standard deviation in reliability-based designs. © 2016, Brazilian Association of Computational Mechanics. All rights reserved. Source


Zidani H.,CNRS Optimisation and Reliability in Structural Mechanics lab | Zidani H.,Sina | Pagnacco E.,CNRS Optimisation and Reliability in Structural Mechanics lab | Sampaio R.,Pontifical Catholic University of Rio de Janeiro | And 2 more authors.
Engineering Optimization | Year: 2013

In this article two linear problems with random Gaussian loading are transformed into multi-objective optimization problems. The first problem is the design of a pillar geometry with respect to a compressive random load process. The second problem is the design of a truss structure with respect to a vertical random load process for several frequency bands. A new algorithm, motivated by the Pincus representation formula hybridized with the Nelder-Mead algorithm, is proposed to solve the two multi-objective optimization problems. To generate the Pareto curve, the normal boundary intersection method is used to produce a series of constrained single-objective optimizations. The second problem, depending on the frequency band of excitation, can have as Pareto curve a single point, a standard Pareto curve, or a discontinuous Pareto curve, a fact that has been reported here for the first time in the literature, to the best of the authors knowledge. © 2013 Taylor & Francis Group, LLC. Source


Aoues Y.,CNRS Optimisation and Reliability in Structural Mechanics lab | Makhloufi A.,CNRS Optimisation and Reliability in Structural Mechanics lab | El-Hami A.,CNRS Optimisation and Reliability in Structural Mechanics lab | Pougnet P.,Valeo
Civil-Comp Proceedings | Year: 2014

Reliability is a major concern in the microelectronics industry. However, new packaging and assembly technologies and requirements to comply with environmental friendly directives create challenges in assuring the reliability of mechatronics products for higher performance and lower cost. Deterministic design modelling does not take into account the uncertainties of design parameters and the variability of operating conditions in service. In this paper, reliability-based design optimization (RBDO) is developed to search for the optimal geometrical configuration of the solder so that fatigue performances are better. Moreover, the RBDO formulation allows for dealing with uncertainties related to geometrical dimensions and temperature loading. The RBDO approach is combined with the kriging approximation in order to surrogate the thermo-mechanical nonlinear finite element model. This paper demonstrates the effectiveness of the RBDO method with the kriging metamodel to conduct the design optimization of complex structures. © Civil-Comp Press, 2014. Source


Poupardin A.,CNRS Laboratory of Waves and Complex Media | Perret G.,CNRS Laboratory of Waves and Complex Media | Pinon G.,CNRS Laboratory of Waves and Complex Media | Bourneton N.,CETE | And 2 more authors.
European Journal of Mechanics, B/Fluids | Year: 2012

This paper presents the vortex dynamics generated by the interaction of a submerged horizontal plate, considered as a vortex generator, and a monochromatic wave. The velocity and vorticity fields are determined experimentally using PIV technique for different resolutions in order to study the global flow around the plate and the formation and advection of vortices upstream and downstream of the plate. The global flow around the plate shows great discrepancies with the potential flow solution: two recirculation cells are formed beneath the plate, the global flow is non-symmetric and the advection of vortices induces strong velocities not represented by the potential flow theory. The formation of vortices at the edges of the plate is characterised. At each period, one vortex is formed at the edge followed by the formation of an opposite sign vortex. The upstream and downstream vortex pairs are then advected in front of the plate and toward the bottom respectively, over a distance of about one third the plate length. The lifetime of vortices is about two wave periods. This study will help us validate a numerical software to be used for analysing the influence of various parameters on the dynamics. These results will be presented in the second part of this paper. © 2012 Elsevier Masson SAS. All rights reserved. Source


Makhloufi A.,CNRS Optimisation and Reliability in Structural Mechanics lab | Aoues Y.,CNRS Optimisation and Reliability in Structural Mechanics lab | El-Hami A.,CNRS Optimisation and Reliability in Structural Mechanics lab
Civil-Comp Proceedings | Year: 2014

This paper presents a numerical investigation of the probabilistic approach in estimating the reliability of wire bonding for microelectronic device structures. The finite element simulation model is used to analyze the sequence of the failure events in power microelectronic devices. This numerical model is used to estimate the probability of failure of power module regarding the wire bonding connection. However, as a result of the time-consuming methods of the multiphysics finite element simulation, a kriging metamodel is used as a surrogate for the response output of the limit state, in this way the reliability analysis is performed directly to the kriging approximation by using the FORM/SORM methods. This study demonstrates the appropriateness of using the reliability approach to predict the effects of the wire bonding failure of power modules. © Civil-Comp Press, 2014. Source

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