CNRS Optimisation and Reliability in Structural Mechanics lab

Rouen, France

CNRS Optimisation and Reliability in Structural Mechanics lab

Rouen, France

Time filter

Source Type

Mycek P.,CNRS Laboratory of Waves and Complex Media | Mycek P.,French Research Institute for Exploitation of the Sea | Gaurier B.,French Research Institute for Exploitation of the Sea | Germain G.,French Research Institute for Exploitation of the Sea | And 3 more authors.
International Journal of Marine Energy | Year: 2013

The understanding of interaction effects between marine energy converters represents the next step in the research process that should eventually lead to the deployment of such devices. Although some a priori considerations have been suggested recently, very few real condition studies have been carried out concerning this issue. Trials were run on 1/30th scale models of three-bladed marine current turbine prototypes in a flume tank. The present work focuses on the case where a turbine is placed at different locations in the wake of a first one. The interaction effects in terms of performance and wake of the second turbine are examined and compared to the results obtained on the case of one single turbine. Besides, a three-dimensional software, based on a vortex method is currently being developed, and will be used in the near future to model more complex layouts. The experimental study shows that the second turbine is deeply affected by the presence of an upstream device and that a compromise between individual device performance and inter-device spacing is necessary. Numerical results show good agreement with the experiment and are promising for the future modelling of turbine farms. © 2013 Elsevier Ltd. All rights reserved.


Mycek P.,CNRS Laboratory of Waves and Complex Media | Mycek P.,French Research Institute for Exploitation of the Sea | Gaurier B.,French Research Institute for Exploitation of the Sea | Germain G.,French Research Institute for Exploitation of the Sea | And 3 more authors.
Renewable Energy | Year: 2014

The ambient turbulence intensity in the upstream flow plays a decisive role in the behaviour of horizontal axis marine current turbines.Experimental trials, run in the IFREMER flume tank in Boulogne-Sur-Mer (France) for two different turbulence intensity rates, namely 3% and 15%, are presented. They show, for the studied turbine configuration, that while the wake of the turbine is deeply influenced by the ambient turbulence conditions, its mean performances turn out to be slightly modified.The presented conclusions are crucial in the view of implanting second generation turbines arrays. In addition, complete and detailed data sets (wake profiles and performance graphs) are made available to the scientific community in order to encourage further comparisons. © 2014 Elsevier Ltd.


Mycek P.,CNRS Laboratory of Waves and Complex Media | Mycek P.,French Research Institute for Exploitation of the Sea | Gaurier B.,French Research Institute for Exploitation of the Sea | Germain G.,French Research Institute for Exploitation of the Sea | And 3 more authors.
Renewable Energy | Year: 2014

The future implantation of second generation marine current turbine arrays depends on the understanding of the negative interaction effects that exist between turbines in close proximity. This is especially the case when the turbines are axially aligned one behind another in the flow. In order to highlight these interaction effects, experiments were performed in a flume tank on 3-bladed 1/30th scale prototypes of horizontal axis turbines.This work focuses on the interactions between two horizontal axis marine current turbines, axially aligned with the upstream flow. Thrust and power coefficients function of the rotation speed of the downstream device are presented. Besides, the wake of each turbine is characterised so as to explain their behaviour.A large range of inter-device distances is considered, as well as two upstream turbulence intensity conditions, namely 3% and 15%. This latter parameter deeply influences the behaviour of a marine current turbine and thus plays a preponderant role in the interactions effects between two devices. Indeed, this study points out that, for the considered turbine and blade geometry, higher ambient turbulence intensity rates (15%) reduce the wake effects, and thus allows a better compromise between inter-device spacing and individual performance. © 2014 Elsevier Ltd.


Cherfils J.M.,CNRS Laboratory of Waves and Complex Media | Pinon G.,CNRS Laboratory of Waves and Complex Media | Rivoalen E.,CNRS Laboratory of Waves and Complex Media | Rivoalen E.,CNRS Optimisation and Reliability in Structural Mechanics lab
Computer Physics Communications | Year: 2012

JOSEPHINE is a parallel Smoothed Particle Hydrodynamics program, designed to solve unsteady free-surface flows. The adopted numerical scheme is efficient and has been validated on a first case, where a liquid drop is stretched over the time. Boundary conditions can also be modelled, as it is demonstrated in a second case: the collapse of a water column. Results show good agreement with both reference numerical solutions and experiments. The use of parallelism allows significant reduction of the computational time, even more with large number of particles. JOSEPHINE has been written so that any untrained developers can handle it easily and implement new features. © 2012 Elsevier B.V. All rights reserved.


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.


Huang C.,CNRS Optimisation and Reliability in Structural Mechanics lab | El Hami A.,CNRS Optimisation and Reliability in Structural Mechanics lab | Radi B.,French National Institute for Agricultural Research
Engineering Optimization | Year: 2016

This article proposed a metamodel-based inverse method for material parameter identification and applies it to elastic–plastic damage model parameter identification. An elastic–plastic damage model is presented and implemented in numerical simulation. The metamodel-based inverse method is proposed in order to overcome the disadvantage in computational cost of the inverse method. In the metamodel-based inverse method, a Kriging metamodel is constructed based on the experimental design in order to model the relationship between material parameters and the objective function values in the inverse problem, and then the optimization procedure is executed by the use of a metamodel. The applications of the presented material model and proposed parameter identification method in the standard A 2017-T4 tensile test prove that the presented elastic–plastic damage model is adequate to describe the material's mechanical behaviour and that the proposed metamodel-based inverse method not only enhances the efficiency of parameter identification but also gives reliable results. © 2016 Informa UK Limited, trading as Taylor & Francis Group


Pinon G.,CNRS Laboratory of Waves and Complex Media | Mycek P.,CNRS Laboratory of Waves and Complex Media | Mycek P.,French Research Institute for Exploitation of the Sea | Germain G.,French Research Institute for Exploitation of the Sea | And 2 more authors.
Renewable Energy | Year: 2012

This paper presents numerical computations of three bladed horizontal axis marine current turbines in a uniform free upstream current. The unsteady evolution of the turbine wake is taken into account by some three-dimensional software, developed to assess the disturbances generated in the sea. An unsteady Lagrangian method is considered for these computations using " Vortex Method" ; a velocity-vorticity numerical implementation of the Navier-Stokes equations. The vortex flow is discretised with particles carrying vorticity, which are advected in a Lagrangian frame. The present paper aims at presenting results on both power and thrust coefficient (C P and C T) predictions and wake characterisation, up to ten diameters downstream of the turbine. Moreover, two different marine current turbines configurations are considered: one is taken from literature [1] and the second one is an open-modified version of turbine inspired from previous works [2]. © 2012 Elsevier Ltd.


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.


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.


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.

Loading CNRS Optimisation and Reliability in Structural Mechanics lab collaborators
Loading CNRS Optimisation and Reliability in Structural Mechanics lab collaborators