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1

Effect of the gear local damage and profile error of the gear on the drivetrain dynamic response

Ghorbel A., Zghal B., Abdennadher M., Walha L., Haddar M.

Journal of Theoretical and Applied Mechanics

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2018

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Vol. 56 nr 3

765--779

EN

The dynamic modeling of vibration of a drivetrain is used for increasing our information about vibration generating mechanisms, especially in the presence of some kind of gear faults. This paper describes a research work on the automotive driveline modeling, vibration analysis, and the effect of gear defects on the dynamic behavior of the system. Firstly, main drivetrain components including the engine, clutch, single stage spur gearbox and disc brake are modeled, respectively. The nonlinear dynamic model is simulated by a thirteen degrees of freedom (DOF) system and the nonlinear function is due to the dry friction path. Secondly, two types of defects are modeled and introduced into the spur gear system; local damage and profile error. Then, the nonlinear equations of motion are solved by the numerical Runge Kutta method and a comparative study of the dynamic behavior of the system in healthy and defected cases is discussed for each fault type. The influence of the defects on the vibration response is presented in the time and frequency domain. Finally, analysis of the two defects together is presented.

2

Porous material effect on gearbox vibration and acoustic behavior

Letaief M. R., Walha L., Taktak M., Chaari F., Haddar M.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 4

1381--1395

EN

In this paper, we define a resolution method to study the effect of a porous material on vibro-acoustic behavior of a geared transmission. A porous plate is coupled with the gearbox housing cover. The developed model depends on the gearbox characteristic and poroelastic parameters of the porous material. To study the acoustic effect of the housing cover, the acoustic transmission loss is computed by simulating numerically the elastic-porous coupled plate model, and the numerical implementation is performed by directly programming the mixed displacement-pressure formulation. To study the vibration effect, the bearing displacement is computed using a two-stage gear system dynamical model and used as the gearbox cover excitation. Numerical implementation is performed by direct programming of the Leclaire formulation.

3

Influence of uncertainty in aerodynamic performance on the dynamic response of a two stage gear system

Tounsi M., Beyaoui M., Abboudi K., Feki N., Walha L., Haddar M.

Journal of Theoretical and Applied Mechanics

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2016

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Vol. 54 nr 2

601--612

EN

In this paper, the nonlinear dynamic response in a wind turbine system is considered and the quantification of uncertainty effects on the variability of this nonlinear response is investigated. Under dynamic conditions, a lumped model with 12 degrees of freedom is proposed taking into account the uncertainty associated to the power coefficient of the input aerodynamic torque. The dynamic response of the two-stage spur gear system is obtained using ODE45 solver of Matlab. The Polynomial Chaos (PC) method is used to introduce the uncertainties on the proposed model. A comparison between the two dynamic responses given by the proposed lumped dynamic model takes into account the uncertainty. It is performed on the existed model without uncertainty. Thus, the efficiency and robustness of the proposed new methodology is evaluated.

4

Dynamic response of a spur gear system with uncertain parameters

Guerine A., Hami A. E., Walha L., Fakhfakh T., Haddar M.

Journal of Theoretical and Applied Mechanics

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2016

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Vol. 54 nr 3

1039--1049

EN

In this paper, we propose a new approach for taking into account uncertainties based on the projection on polynomial chaos. The new approach is used to determine the dynamic response of a spur gear system with uncertainty associated to gear system parameters. The simulation results are obtained by the polynomial chaos approach for dynamic analysis under uncertainty. The proposed approach is an efficient probabilistic tool for uncertainty propagation. It has been found to be an interesting alternative to the parametric studies. The polynomial chaos results are compared with Monte Carlo simulations.

5

Nonlinear Dynamic Behaviour of a Clutch System Affected by Parallel and Angular Misalignment

Walha L., Driss Y., Fakhfakh T., Haddar M.

Machine Dynamics Problems

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2009

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Vol. 33, No. 1

114-130

EN

The inherent problems of rotating machine dysfunction are often caused by shaft misalignment. This defect generates some important loads and vibrations, and can lead to a premature failure of the bearing, the shaft, or the clutch. In this study we propose a model of a clutch having eleven degree of freedom and three types of nonlinearity introduced by dry friction, double-stages stiffness and splines clearances. The Coulomb friction formulations and splines clearance functions are smoothened before they are applied to the nonlinear system. The calculation of the dynamic response of the clutch is done by the Runge Kutta method. The dynamic behaviour of both a faultless clutch system and clutch system containing a parallel and angular misalignment defect are compared in the time domains. Finally, the effects of a harmonically varying load on the dynamic response of the defected clutch system with nonlinear dry friction and under sinusoidal torque excitation are analysed.

6

Dynamic Response of Two-Stage Gear System Damaged by Teeth Defects

Walha L., Louati J., Fakhfakh T., Haddar M.

Machine Dynamics Problems

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2005

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Vol. 29, No. 3

107--124

EN

In this paper, a linear time varying plane model of two stage spur gear system is formed to investigate the dynamic response for general spur gear location in the gearbox. The excitation is induced by two gear meshes stiffness fluctuations. This case describes the real working of the gearings. The calculation of the dynamic response is done by a step-by-step time integration method (Newmark method). One case of gears location is treated. Severe working conditions can lead to the system failure. Tooth crack and teeth scaling are one of these damages. They can occur on the first gear mesh contact and/or on the second one. In this paper they are discussed and modelled in the case of a two-stage gear system. The dynamic behavior of the healthy gear system and the defected one are compared both in the time domain and in the frequency domain. Wigner-Ville distribution method is used to show the dynamic behavior in the joint time-frequency domain and to localize the defected teeth.