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Monastir, Tunisia

Benkedjouh T.,Laboratoire Of Mecanique Des Structures Lms | Medjaher K.,CNRS Femto ST Institute | Zerhouni N.,CNRS Femto ST Institute | Rechak S.,Laboratoire genie mecanique
PHM 2012 - 2012 IEEE Int. Conf.on Prognostics and Health Management: Enhancing Safety, Efficiency, Availability, and Effectiveness of Systems Through PHM Technology and Application, Conference Program

This paper presents a method for fault prognostic of bearings based on Principal Component Analysis (PCA) and Support Vector Data Description (SVDD). The purpose of the paper is to transform the monitoring vibration signals into features that can be used to track the health condition of bearings and to estimate their remaining useful life. PCA is used to reduce the dimensionality of original vibration features by removing the redundant ones. SVDD is a pattern recognition method based on structural risk minimization principles. In this contribution, the SVDD is used to fit the trained data to a hypersphere such that its radius can be used as a health indicator. The proposed method is then applied on real bearing degradation performed on an accelerated life test. The experimental results show that the health indicator reflects the bearing's degradation. © 2012 IEEE. Source

Naimi S.,Laboratoire genie mecanique | Chouchane M.,Laboratoire genie mecanique | Ligier J.-L.,Renault S.A.
Comptes Rendus - Mecanique

A theoretical prediction of the steady state characteristics of a hydrodynamic short bearing with a circumferential central feeding groove is presented. An implicit relationship between the lubricant feeding pressure, the Sommerfeld number and the bearing eccentricity has been derived and used to investigate the effect of the feeding groove and supply pressure on the pressure field of the oil film and the bearing eccentricity. Curves relating the eccentricity to the Sommerfeld number for various supply pressures are presented and compared with published data obtained using numerical methods. A simplified explicit model has also been derived and shown to be useful for low Sommerfeld numbers. The steady state bearing characteristics predicted by the presented model are in good agreement with those of other published research work using other approaches. © 2010 Académie des sciences. Source

Belghith S.,Laboratoire genie mecanique | Mezlini S.,Laboratoire genie mecanique | BelhadjSalah H.,Laboratoire genie mecanique | Ligier J.-L.,Renault S.A.
Comptes Rendus - Mecanique

In this study, microscopic deterministic and analytical contact models that take the properties of engineering surfaces into account have been developed. Geometrical characteristics of rough surfaces are deduced using the standard procedure for roughness and waviness parameters. These models allow the analyses of the asperities behaviour and real contact area. Comparison between the analytical and deterministic results shows a good correlation. The microscopic model is often enabling to simulate the real structure with complex geometry, so, a homogenisation technique has been developed. The interface of the equivalent model has been governed by the microscopic model results. Sensitivity of models responses to the random pulling of surfaces parameters has been also analysed. © 2009 Académie des sciences. Source

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