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Published Articles

The Volume 3, No 3, September 1998

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Determination of the Complex Moduli of Viscoelastic Isolator Mounts by Finite Element Modeling and Vibration Testing

Stanley G. Hutton, Guoping Chen


An investigation aimed at determining the complex moduli for a number of polymeric materials is discussed. The complex moduli are determined over a particular frequency range on the basis of transmissibility measurements conducted on mass loaded cube-like specimens subjected to controlled base harmonic excitation. An equivalent one dimensional viscoelastic model is created by condensation of the governing equations and the use of an elastic finite element calculation. Complex moduli are determined by comparison of the transmissibilities measured and those predicted by the condensed model. Consideration is also given to the manner in which the experimental data may be fitted as an analytic function of frequency and to the errors that are involved.

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Determination of Loudspeaker Characteristics by Numerical Modeling and Measurements

Andre L. Goldstein and Samir N.Y. Gerges


The frequency response prediction of loudspeakers has a closed-form analytical solution only for low frequencies and simple geometries. This paper presents the use of the finite element method and the boundary element method to extend the prediction of loudspeaker response to higher frequencies to allow consideration of the flexible behavior of the diaphragm. The modeling of a commercial loudspeaker is performed considering the axisymmetry of the system, and its frequency response and directivity are calculated. The procedure used to obtain the material properties is also presented. The computational results were compared with measurements made in a hemi-anechoic chamber and show good agreement. The FEM modal analysis of a three-dimensional model was performed and compared with results from an experimental modal analysis. The comparison gives some insight into the validity of the simplifications assumed in the axisymmetrical model adopted to predict the sound pressure response.

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Fatigue under Complex Loading History in a Random Vibration Environment - a Survey

Yi Gong and Michael P. Norton


In this paper, various fatigue life regimes, life assessment approaches and their implications in design are summarised. Emphasis is placed on modelling fatigue under complex loading history in random vibration environments. Factors affecting the fatigue life of materials and structural components are presented. Multi-axial random fatigue problems are also discussed.

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