Layout of Extensional Surface Damping Treatment for Minimal Resonance Response

1993 ◽  
Author(s):  
Hans-Walter Wodtke ◽  
Hans A. Eschenauer ◽  
John S. Lamancusa
Keyword(s):  
Sound Radiation ◽  
Frequency Interval ◽  
Response Functions ◽  
Optimal Layout ◽  
Circular Plates ◽  
Spherical Shells ◽  
Single Degree Of Freedom ◽  
Metal Structures ◽  
Single Degree ◽  
Resonance Response

Abstract The efficiency of using surface-mounted damping layers for noise-reduction of thin-walled (sheet metal) structures, largely depends on their distribution on the component. It is therefore attempted — by using FEM and Mathematical Programming (MP) procedures — to determine optimal layer distributions in such a way that the resonance amplitudes in a frequency interval become minimal. An approximation method based on damped single degree of freedom response functions is used for resonance tracking. Beams, circular plates and shallow spherical shells with unconstrained damping treatment are considered as application examples. It will be shown that an optimal layout of the layers can result in substantial reductions in sound radiation. These reductions result not only from an increase in damping and stiffness but may also be due to a modification of the vibration modeshapes.

Frequency Domain Analysis of a Fractional Derivative SDOF System

2005 ◽  
Author(s):  
Silvio Sorrentino ◽  
Luigi Garibaldi
Keyword(s):  
Magnetic Material ◽  
Fractional Derivative ◽  
Frequency Response ◽  
Frequency Domain ◽  
Dynamic Behaviour ◽  
Frequency Domain Analysis ◽  
Response Functions ◽  
Single Degree Of Freedom ◽  
Sdof System ◽  
Single Degree

This paper presents a study of the frequency domain behaviour of a single degree of freedom (SDOF) system with a fractional derivative model, named Fractional Kelvin-Voigt. Frequency response functions (FRFs) as receptance and transmissibility are analytically studied. Then the model is applied to describe the dynamic behaviour of a magneto-mechanic system in the frequency domain, consisting of a body of para or dia-magnetic material vibrating in a field created by a pair of magnets.

SDOF Models for RC and FRC Circular Plates under Blast Loads

2011 ◽  
Vol 82 ◽  
pp. 440-445 ◽  
Author(s):  
Matteo Colombo ◽  
Paolo Martinelli
Keyword(s):  
Reinforced Concrete ◽  
Shock Tube ◽  
Pressure Wave ◽  
Fibre Reinforced Concrete ◽  
Circular Plates ◽  
Blast Loads ◽  
Single Degree Of Freedom ◽  
Simply Supported ◽  
Single Degree ◽  
Slabs On Ground

This work presents simplified models, in the form of single degree of freedom (SDOF)elasto-plastic systems, for the dynamic analysis of traditional reinforced concrete (RC) and fibre-reinforced concrete (FRC) circular plates under blast loads. Two cases have been examined inthis study: simply supported and resting on Winkler-type soil plates. Both cases intend toprovide a simplified tool for predicting the response respectively for specimens subjected toblast pressure wave inside shock-tube facilities and for slabs on ground under blast loads. Thesecond case also represents the loading conditions inside a new shock tube facility specificallyintended for the investigation of underground tunnel lining subjected to blast loads.

Calculation of the Response of an Impulsively Excited Oscillator in an Infinite Acoustic Fluid

1981 ◽  
Vol 48 (4) ◽  
pp. 749-752 ◽  
Author(s):  
A. V. Clark ◽  
A. M. Whitman
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Sound Radiation ◽  
Wave Number ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Principal Effect ◽  
Hydrodynamic Solution ◽  
Acoustic Fluid ◽  
Excited Oscillator

The response of an impulsively excited single-degree-of-freedom oscillator submerged in an infinite acoustic fluid is considered. The character of the response is determined by the quantity ka; k is the wave number associated with the in-vacuo natural frequency of the oscillator, and a is a characteristic structural dimension. For low-frequency oscillators (ka ≪ 1), the response consists of two parts. The first is the usual hydrodynamic solution in which the effect of the fluid on the structure is that of an added mass. The second is much smaller (of order ka) and is significant only in a “boundary layer” in time of order a/c, with c the fluid sonic velocity. For high-frequency oscillators (ka ≫ 1), the principal effect of the fluid is a decay of oscillator vibration due to sound radiation.

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