scholarly journals Complex-Damped Dynamic Systems in the Time and Frequency Domains

2004 ◽  
Vol 11 (3-4) ◽  
pp. 209-225 ◽  
Author(s):  
Elvio Bonisoli ◽  
John E. Mottershead
Keyword(s):  
Frequency Response ◽  
Structural Dynamics ◽  
Dynamic Systems ◽  
Dynamic Behaviour ◽  
Root Locus ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Frequency Domains ◽  
Spring System ◽  
Mass Spring

The fact that a complex-damped model may represent the dynamic behaviour of elasto-mechanical systems when acted upon by a magnetic field was brought to the attention of the structural dynamics community very recently by Professor Bruno A. D. Piombo and his colleagues at the Politecnico di Torino. In this paper a thorough analysis of the single degree-of-freedom complex-damped mass-spring system is presented. The analysis includes the root locus, the (non-causal) impulse response, the frequency response and the transmissibility. Regions of different behaviour in the frequency response and transmissibility are described in detail. The stiffening behaviour observed in Prof. Piombo's experiments and known as the "phantom effect" is demonstrated by the complex-damped model.

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.

Prediction and Evaluation of Sensitivity to Transient Accelerations

1954 ◽  
Vol 21 (4) ◽  
pp. 371-380
Author(s):  
M. Kornhauser
Keyword(s):  
Field Measurements ◽  
Laboratory Methods ◽  
Single Degree Of Freedom ◽  
Acceleration Time ◽  
Single Degree ◽  
Spring System ◽  
Service Conditions ◽  
Sensitivity Data ◽  
Mass Spring ◽  
The Ideal

Abstract The determination, presentation, and interpretation of inertia-sensitivity data are discussed with application to inertia devices and to shock-resistant structures. Theoretical analysis of the single-degree-of-freedom system for response to acceleration-time pulses, amplification factors, and inertia sensitivity are used as a basis for discussion of actual devices. Effects of deviations from the ideal mass-spring system are considered. Practical use of sensitivity data is discussed with regard to the reliability of laboratory methods, the accuracy of field measurements, and variability of service conditions. Criteria are suggested for design of inertia mechanisms and design of structures for resistance to shock.

On Running a Machine through its Resonant Frequency

1956 ◽  
Vol 60 (549) ◽  
pp. 620-621 ◽  
Author(s):  
J. P. Ellington ◽  
H. McCallion
Keyword(s):  
High Speed ◽  
Exciting Force ◽  
Linear Mass ◽  
Running Speed ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Constant Rate ◽  
Summation Of Series ◽  
Spring System ◽  
Mass Spring

A solution, in terms of known integrals, is obtained for the motion from rest of a machine, idealised as an undamped linear mass-spring system, when subjected to an exciting force whose frequency varies at a constant rate.In many installations of modern high speed machinery the running speed of the machine is in excess of the resonant or natural frequency of the system, and consequently starting up or stopping the machine could result in vibrations of large amplitude. The problem of assessing the magnitude and duration of these vibrations is very complicated and has been solved analytically only for the case of a single degree of freedom system excited by an oscillating force whose frequency varies linearly with time. However, even this solution is not easy to evaluate, the integrals involved demanding either graphical construction and numerical integration or summation of series.

The Active Control of Forced Vibration Produced by Arbitrary Disturbances

1985 ◽  
Vol 107 (1) ◽  
pp. 33-37 ◽  
Author(s):  
J. S. Burdess ◽  
A. V. Metcalfe
Keyword(s):  
Vibration Control ◽  
Active Control ◽  
Forced Vibration ◽  
Disturbance Observer ◽  
Degree Of Freedom ◽  
Experimental Results ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Impact Forces ◽  
Mass Spring

This paper considers the vibration control of a single degree of freedom mass-spring-damper system when subjected to an arbitrary, unmeasurable disturbance. The idea of a disturbance observer is introduced and it is shown how an estimate of the excitation can be derived and used to generate a control, which reduces the vibration. This control is shown to be robust with respect to the parameters describing the behavior of the system. Experimental results are presented which show the efficacy of the method when the system is excited by periodic, random, and impact forces. Comments are made on the application of the method.

An Efficient Method for Compensating Truncated Higher Modes in Structural Dynamics Modification

1986 ◽  
Vol 200 (1) ◽  
pp. 41-48 ◽  
Author(s):  
K R Chung ◽  
C W Lee
Keyword(s):  
Structural Dynamics ◽  
Efficient Method ◽  
Curve Fitting ◽  
Modal Parameters ◽  
Frequency Range ◽  
Single Degree Of Freedom ◽  
Higher Modes ◽  
Numerical Example ◽  
Single Degree ◽  
Damped Systems

An efficient method for compensating the effects of the truncated higher modes in structural dynamics modification (SDM) is developed to predict the accurate modal parameters of locally modified structures. The effects of the truncated higher modes are represented by a fictitious, effective mode residing beyond the frequency range of interest. The modal parameters are then easily obtained by the iterative single degree-of-freedom curve-fitting technique developed for lightly damped systems. A numerical example demonstrates the effectiveness of the improved SDM technique.

scholarly journals OPTIMIZATION OF TUNED MASS DAMPERS ATTACHED TO DAMPED STRUCTURES - MINIMIZATION OF MAXIMUM DISPLACEMENT AND ACCELERATION

2021 ◽  
Vol 30 ◽  
pp. 98-103
Author(s):  
Jan Štěpánek ◽  
Jiří Máca
Keyword(s):  
Frequency Response ◽  
Dynamic Behaviour ◽  
Harmonic Force ◽  
Tuned Mass Dampers ◽  
Maximum Displacement ◽  
Single Degree Of Freedom ◽  
Design And Optimization ◽  
Mass Damper ◽  
Proper Design ◽  
Structure Properties

A tuned mass damper is a device, which can be highly helpful while dealing with dynamic behaviour of structures. Its proper design is conditioned by knowledge of both loading and the structure properties. In many cases, the structure can be represented by single degree of freedom model, which simplifies the design and optimization of tuned mass dampers. Most of studies focus only on minimization of displacement of the main structure under harmonic force load, however, in many cases, different frequency response function would be more appropriate. This paper presents an extension of design formulas for the H∞ optimization of tuned mass dampers for damped structures and various frequency response functions.

Analytical Procedure for Prediction of Radiated Noise From a Gear-Shaft-Plate System

2000 ◽  
Author(s):  
Chan Il Park
Keyword(s):  
Circular Plate ◽  
Analytical Procedure ◽  
Housing System ◽  
Single Degree Of Freedom ◽  
Gear Noise ◽  
Radiated Noise ◽  
Gear Mesh ◽  
Single Degree ◽  
The Moment ◽  
Mass Spring

Abstract In order to predict the gear noise, a simplified model of gear-shaft-housing system is studied. The gear is modeled as a single degree of freedom mass-spring-damper system. The shaft-housing system is modeled as a clamped circular plate connected with a beam. The moment components of the beam excited by the gear mesh force are considered in the calculation of the plate vibration and radiated noise. The displacements of the clamped circular plate due to the r-direction moment and θ-direction moment are analytically derived. Radiated noise from the plate is also derived using Rayleigh integral. Using the derived results, the numerical examples are given.

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