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Sinou J.-J.,CNRS Tribology and Dynamic Systems Laboratory
Mechanics Research Communications | Year: 2012

The identification of new scientific challenges, as well as the increasing high-performance computing support, indicates that the benefits of applying novel nonlinear techniques for crack detection will continue to grow. So, significant effort has been invested in recent years to develop effective techniques to detect crack in mechanical structures. The objective of this paper is to discuss and propose a robust diagnostic of damage based on non-linear vibrational measurements with particular regard to the Higher-Order Frequency Response Functions. An important observation is that the appearances of the non-linear harmonic components and the emerging anti-resonances in Higher-Order Frequency Response Functions can provide useful information on the presence of cracks and may be used on an on-line crack monitoring system for small levels of damage. Efficiency of the proposed methodology is illustrated through numerical examples for a pipeline beam including a breathing crack. © 2012 Elsevier Ltd. All rights reserved.

Mathia T.G.,CNRS Tribology and Dynamic Systems Laboratory | Pawlus P.,Rzeszow University of Technology | Wieczorowski M.,Poznan University of Technology
Wear | Year: 2011

This paper describes future trends in surface metrology. Measurement techniques are briefly mentioned. A special attention was paid to tactile and optical methods. Selected problems of surface topography characterization are described. The effects of sampling and filtering on surface topography representation are analysed. Structured surfaces are becoming both technologically and economically critical. Therefore their description is a problem of a great practical importance. Multi-process textures are very important from functional point of view. Various methods of their description are compared. Surface texturing as a means for enhancing tribological properties of frictional pairs started to be extremely popular from for about last 10 years. The effects of surface texturing on improving tribological properties of sliding assemblies are analysed. The other influences of surface topography are mentioned in this paper. © 2010 Elsevier B.V.

Feulvarch E.,CNRS Tribology and Dynamic Systems Laboratory
Comptes Rendus - Mecanique | Year: 2012

A Lagrangian approach is proposed for modeling interdiffusion phenomena in solid metals. In the first section, a formulation of diffusion equations in terms of mass fraction is developed. The specificity of this approach lies in the choice of the convection velocity. In this work, it is defined as being equal to the massic average velocity. An interdiffusion strain rate tensor is also proposed to model the mass movements induced by interdiffusion phenomena. In the second section, a finite element procedure is proposed to simulate the coupled problem which includes diffusion equations and momentum balance. A one-dimensional example is presented to show the relevance of the approach developed for an interdiffusion couple. © 2012 Académie des sciences.

Sinou J.-J.,CNRS Tribology and Dynamic Systems Laboratory
Journal of Vibration and Acoustics, Transactions of the ASME | Year: 2012

This paper proposes to use a polynomial chaos expansion approach to compute stochastic complex eigenvalues and eigenvectors of structures including damping or gyroscopic effects. Its application to a finite element rotor model is compared to Monte Carlo simulations. This lets us validate the method and emphasize its advantages. Three different uncertain configurations are studied. For each, a stochastic Campbell diagram is proposed and interpreted and critical speeds dispersion is evaluated. Furthermore, an adaptation of the Modal Accordance Criterion (MAC) is proposed in order to monitor the eigenvectors dispersion. © 2012 American Society of Mechanical Engineers.

Fabbri A.,CNRS Tribology and Dynamic Systems Laboratory | Fen-Chong T.,University Paris Est Creteil
Cold Regions Science and Technology | Year: 2013

The goal of this paper is to investigate the validity of indirectly built ice content curves from porous network characterization tests to predict the behavior of a freezing cement based material. To do so, the results obtained by the two classical methods, namely the mercury intrusion porosimetry (MIP) and the gravimetric water desorption (WD) tests, are compared with the direct measurement of the ice content with a dielectric capacitive apparatus. A corrective approach, based on an interface energy analysis between the in-pore phases, is proposed in order to increase the accuracy of MIP based prediction of the ice saturation curve. The impact of the method used to estimate the ice saturation curve on the behavior of freezing porous medium is evaluated and discussed in the framework of poromechanics. © 2013 Elsevier B.V.

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