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acoustics and vibrations

Antonio Papangelo's picture

Critical thresholds for mode-coupling instability in viscoelastic sliding contacts

Mode-coupling instabilities are known to trigger self-excited vibrations in sliding contacts. Here, the conditions for mode-coupling (or "flutter") instability in the contact between a spherical oscillator and a moving viscoelastic substrate are studied. The work extends the classical 2-Degrees-Of-Freedom conveyor belt model and accounts for viscoelastic dissipation in the substrate, adhesive friction at the interface and non-linear normal contact stiffness as derived from numerical simulations based on a boundary element method capable of accounting for linear viscoelastic effects.

Giorgio Carta's picture

Quasi-periodicity and multi-scale resonators for the reduction of seismic vibrations in fluid-solid systems

This paper presents a mathematical model for an industry-inspired problem of vibration isolation applied to elastic fluid-filled containers. A fundamental problem of suppression of vibrations within a finite-width frequency interval for a multi-scale fluid-solid system has been solved. We have developed a systematic approach employing full fluid-solid interaction and dispersion analysis, which can be applied to finite and periodic multi-scale systems.

SIMPLE ACOUSTICS PROBLEM

DEAR all

I want to knowthe following:

A circular diaphragm of 1mm diameter, is vibrating with the amplitude of 100 microns at frequency 1000 Hz. What is the sound output at 10 mm distance??

Looking for a Postdoc position in the filed of vibration aided fault diagnosis

I am going to finnish my Ph.D. of mechanical engineering with a thesis in the field of vibration assisted fault diagnosis in about 3 months. My main field of research is vibration and I have worked extensively on gear systemes vibration modeling and diagnostics. 

Currently I am looking for a postdoc position at which I can continue my researches in the abovesaid fields.

my Email address is b_hoseini@kntu.ac.ir

Thanks

Aman Haque's picture

Position Open: William E. Diefenderfer Chair in Mechanical Engineering at Penn State University

Dear Colleagues:

The Department of Mechanical and Nuclear Engineering at The Pennsylvania State University is seeking applicants for the William E. Diefenderfer Chair in Mechanical Engineering. Attached is a flyer for your information. Please let me know if you have any questions.

Sincerely

Aman Haque

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