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El Hafidi A.,CNRS Research Department of Automotive Engineering | Martin B.,University of Burgundy | Loredo A.,CNRS Research Department of Automotive Engineering | Jego E.,RATP
Mechanical Systems and Signal Processing | Year: 2010

This study is composed of three essential parts. The first part describes an indirect semi-experimental method which is used to reconstruct the excitation force of an operating diesel engine from the acceleration data measured at the mounting points. These internal forces can not be directly measured with force sensors; they have to be derived from the dynamic deformation of the engine support, so a theoretical analysis is carried out to derive the equations for the force re-construction. The second part deals with prevention of low frequency vibration of the powertrain from spreading to the rest of the vehicle. Three uncoupling techniques are used to minimize these vibrations. The first technique reduces the non-diagonal elements of stiffness matrix. The second technique uses the elastic axes decoupling criterion. The third technique uncouple the torque roll axis (TRA) by using the previously determined excitation efforts. In the third part, numerical and experimental results are discussed. The solicitations deducted and the positions of mounts allowing decoupling of the powertrain are presented. © 2010 Elsevier Ltd. All rights reserved.


Sophy T.,CNRS Research Department of Automotive Engineering | Silva A.D.,CNRS Research Department of Automotive Engineering | Kribeche A.,CNRS Research Department of Automotive Engineering | Sadat H.,University of Poitiers
Numerical Heat Transfer, Part B: Fundamentals | Year: 2016

The aim of this work is the development of a space–time diffuse approximation meshless method (DAM) to solve heat equations containing discontinuous sources. This work is devoted to transient heat transfer problems with static and moving heat sources applied on a metallic plate and whose power presents temporal discontinuities. The space–time DAM using classical weight function is convenient for continuous transient heat transfer. Nevertheless, for problems including discontinuities, some spurious oscillations for the temperature field occur. A new weight function, respecting the principle of causality, is used to eradicate the physically unexpected oscillations. 2016 Copyright © Taylor & Francis Group, LLC


Gong X.J.,CNRS Research Department of Automotive Engineering | Hurez A.,IUT | Verchery G.,CNRS Research Department of Automotive Engineering
Polymer Testing | Year: 2010

This work covers the problems encountered in correctly determining mode I interlaminar fracture toughness of composite materials. Pure mode I tests were performed on double cantilever beam (DCB) specimens composed by quasi-homogeneous and uncoupled multidirectional (MD) laminates using 16 or 26-ply: [α/-α2/α/-α/α2/- α]sym or anti-sym and [0/α/-α/02/- α/0/α/02/α/-α/0]sym, with α = 0°,15°,30°,45°,90°. A finite element analysis shows that the non-uniformity ratio β=(GImax-GIav.)/G Iav% depends not only on the parameter Dc = D 12 2/(D11D22), but also on the specimen geometrical ratios a/b and a/h. The condition of Dc<0.25 is not sufficient to assure a uniform GI width-wise distribution. If we want to study the crack growth between any ply angles, it is difficult to find lay-ups having β<10%. In fact, the crack initiation in MD DCB specimens usually occurred at the middle of the specimens, where GI attained a maximum. Hence, the critical energy release rate GIC has to be measured by the maximum instead of the mean of GI. © 2010 Elsevier B.V. All rights reserved.


Bert J.,CNRS Research Department of Automotive Engineering | Chrenko D.,CNRS Research Department of Automotive Engineering | Sophy T.,CNRS Research Department of Automotive Engineering | Le Moyne L.,CNRS Research Department of Automotive Engineering | Sirot F.,Danielson Engineering
Energy | Year: 2014

A Stirling engine with nominal output power of 1kW is tested using air and helium as working gases. The influence of working pressure, engine speed and temperature of the hot source is studied, analyzing instantaneous gas pressure as well as instantaneous and stationary temperature at different positions to derive the effective power. A zero dimensional finite-time thermodynamic, three zones model of a generic Stirling engine is developed and successfully validated against experimental gas temperature and pressure in each zone, providing the effective power. This validation underlines the interest of different working gases as well as different geometric configurations for different applications. Furthermore, the validated model allows parametric studies of the engine, with regard to geometry, working gas and engine kinematics. It is used in order to optimize the kinematic of a Stirling engine for different working points and gases. © 2014 Elsevier Ltd.


Bert J.,CNRS Research Department of Automotive Engineering | Chrenko D.,CNRS Research Department of Automotive Engineering | Sophy T.,CNRS Research Department of Automotive Engineering | Le Moyne L.,CNRS Research Department of Automotive Engineering | Sirot F.,Danielson Engineering
Renewable Energy | Year: 2012

A novel zero dimensional finite-time thermodynamic, three zones (compression, expansion and regenerator volumes) model of a generic Stirling engine has been developed. Time-dependant heat transfers and losses are considered in the three zones and with the surrounding. The model calculates the evolution of gas temperature, mass and pressure in each zone. Parametric studies and optimization of the engine are facilitated due to easy change of multiple engine parameters. Experimental validation of the model and calibration of transfer coefficients are carried out over a large range of temperature and rotation speed through comparison with a scaled instrumented engine for different geometrical configurations. © 2012 Elsevier Ltd.


Dupont T.,CNRS Research Department of Automotive Engineering | Leclaire P.,CNRS Research Department of Automotive Engineering | Panneton R.,Université de Sherbrooke
Journal of the Acoustical Society of America | Year: 2013

The acoustic properties of porous materials containing dead-end (DE) pores have been proposed by Dupont [J. Appl. Phys. 110, 094903 (2011)]. In the theoretical description, two physical parameters were defined (the dead-end porosity and the average length of the dead-end pores). With the knowledge of the open porosity (measured with non-acoustic methods), and the measurement of kinematic porosity (also called the Biot porosity in this article), it is possible to deduce the dead-end porosity. Two acoustic methods for measuring the Biot porosity for a wide range of porosities are proposed. These methods are based on acoustic transmission and on the low and high frequency behaviors of acoustic indicators. The low frequency method is valid for high porosities. It involves measurements in a transmission tube and the knowledge of the theoretical asymptotic behavior of the phase velocity at high frequencies. The high frequency method is based on ultrasonic measurements and on the high frequency asymptotic behavior of the transmission coefficient. It is well adapted for material with relatively low values of porosity. Good precision was found for both methods and materials containing dead end porosity were tested. © 2013 Acoustical Society of America.


PubMed | CNRS Research Department of Automotive Engineering, University of Technology of Troyes and Université de Sherbrooke
Type: Journal Article | Journal: The Journal of the Acoustical Society of America | Year: 2016

The acoustic properties of an air-saturated macroscopically inhomogeneous aluminum foam in the equivalent fluid approximation are studied. A reference sample built by forcing a highly compressible melamine foam with conical shape inside a constant diameter rigid tube is studied first. In this process, a radial compression varying with depth is applied. With the help of an assumption on the compressed pore geometry, properties of the reference sample can be modelled everywhere in the thickness and it is possible to use the classical transfer matrix method as theoretical reference. In the mixture approach, the material is viewed as a mixture of two known materials placed in a patchwork configuration and with proportions of each varying with depth. The properties are derived from the use of a mixing law. For the reference sample, the classical transfer matrix method is used to validate the experimental results. These results are used to validate the mixture approach. The mixture approach is then used to characterize a porous aluminium for which only the properties of the external faces are known. A porosity profile is needed and is obtained from the simulated annealing optimization process.


Chrenko D.,CNRS Research Department of Automotive Engineering | Chrenko D.,University of Technology of Belfort - Montbéliard
IET Intelligent Transport Systems | Year: 2015

This study covers three main aspects. First, it presents a way to create driving cycles using only driver behaviour (acceleration, deceleration and maximum speed) and route data as input parameters. Second, a power-based approach to describe different vehicle architectures from internal combustion engine vehicle, over stop and start to series and parallel hybrid solutions is presented and respective component modelling approaches are introduced. Finally, the fuel consumption on a given cycle in function of eco-driving parameters is evaluated. It can be seen that hybrid solutions show minimum fuel consumption of about 3 L/100 km, whereas eco-driving habits do change slightly when applied to hybrid architectures because of new technologies such as braking energy recovery. © The Institution of Engineering and Technology 2015.


Asserin O.,CEA Saclay Nuclear Research Center | Loredo A.,CNRS Research Department of Automotive Engineering | Petelet M.,CEA Saclay Nuclear Research Center | Petelet M.,CNRS Research Department of Automotive Engineering | Iooss B.,Électricité de France
Finite Elements in Analysis and Design | Year: 2011

In this paper, the sensitivity analysis methodology is applied to numerical welding simulation in order to rank the importance of input variables on the outputs of the code like distorsions or residual stresses. The numerical welding simulation uses the finite element method, with a thermal computation followed by a mechanical one. Classically, a local sensitivity analysis is performed, hence the validity of the results is limited to the neighbourhood of a nominal point, and cross effects cannot be detected. This study implements a global sensitivity analysis which allows to screen the whole material space of the steel family mechanical properties. A set of inputs of the mechanical model - material properties that are temperature-dependent - is generated with the help of latin hypercube sampling. The same welding simulation is performed with each sampling element as input data. Then, output statistical processing allows us to classify the relative input influences by means of different sensitivity indices estimates. Two different welding configurations are studied. Considering their major differences, they give a different ranking of inputs, but both of them show that only a few parameters are responsible for the variability of the outputs. To illustrate the pertinence of the overall process, for the first of the two configurations, two series of computations are performed: one for a complete sample and one for its reduced version - where all the secondary parameters are set to mean values. They match perfectly, showing a substantial economy can be done by giving mean values to the rest of the inputs. Sensitivity analysis has then provided answers to what we consider one of the probable frequently asked questions regarding welding simulation: for a given welding configuration, which properties must be measured with a good accuracy and which ones can be simply extrapolated or taken from a similar material? That leads us to propose a comprehensive methodology for welding simulations including four sequential steps: a problem characterization, a sensitivity analysis, an experimental campaign, simulations. © 2011 Elsevier B.V.


Cheng P.,CNRS Research Department of Automotive Engineering | Gong X.-J.,CNRS Research Department of Automotive Engineering | Hearn D.,CNRS Research Department of Automotive Engineering | Aivazzadeh S.,CNRS Research Department of Automotive Engineering
Composite Structures | Year: 2011

The present study examines the tensile behaviour of composite structures repaired by bonding external patches. Various patches of different stacking sequences placed on both sides of the parent plate were considered. Damage development and the failure process of the repaired plates were analyzed and a parent plate fracture model has been proposed. Optimised patch repairs were calculated by finite element modelling. It was found that high stress concentration along the longitudinal edges of circular patches and/or at the transverse edges of the hole leads to early damage initiation in the parent plate. However, the position of damage initiation and the process of damage progression depend particularly on the properties of repair patches. In order to optimise patch repairs, finite element modelling was used and it was founded possible to attain over 90% of the strength of an unnotched specimen. The optimised patch design can be characterised by an optimal strength ratio R*, which should be minimized when selecting repair parameters. © 2010 Elsevier Ltd.

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