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Effect of Liner Characteristics on the Acoustic Performance of Duct Systems

Othmani C., Hentati T., Taktak M., Elnady T., Fakhfakh T., Haddar M.

Archives of Acoustics

2015

Vol. 40, No. 1

117--127

Porous materials are used in many vibro-acoustic applications. Different models describe their performance according to material’s intrinsic characteristics. In this paper, an evaluation of the effect of the porous and geometrical parameters of a liner on the acoustic power attenuation of an axisymmetric lined duct was performed using multimodal scattering matrix. The studied liner is composed by a porous material covered by a perforated plate. Empirical and phenomenal models are used to calculate the acoustic impedance of the studied liner. The later is used as an input to evaluate the duct attenuation. By varying the values of each parameter, its influence is observed, discussed and deduced.

Dynamic behavior of a rotor supported by angular ball bearings

Abbes M. S., Hentati T., Maatar M., Fakhfakh T., Haddar M.

Diagnostyka

2009

nr 3(51)

3-8

The wide range and large scale usage of rolling bearings indicates their necessity and vital contribution to the performance of modern industries. In this paper, a non linear model, predicting mechanical behavior of the loaded angular ball bearing, have been developed. The dynamic behavior of a rotor supported by two angular ball bearings is analyzed. The finite element method is used and the rotor is decritizied on beam elements. A mathematical modal taking account different sources of non linearity: the Hertzian contact force and the action of all balls on the bearings inner races, is developed. The Newmark algorithm coupled with Newton Raphson iterative method is used to solve the non linear differential equation iteratively.