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Research Papers

Vibration Characteristics of Guided Circular Saws: Experimental and Numerical Analyses

[+] Author and Article Information
Ramin M. H. Khorasany

e-mail: raminkh@mech.ubc.ca

Stanley G. Hutton

Department of Mechanical Engineering,
The University of British Columbia,
Vancouver, B.C., Canada, V6T 1Z4

Contributed by Design Engineering Division of ASME for publication in JOURNAL OF VIBRATION AND ACOUSTICS. Manuscript received June 27, 2011; final manuscript received February 17, 2012; published online September 10, 2012. Assoc. Editor: Walter Lacarbonara

J. Vib. Acoust 134(6), 061004 (Sep 10, 2012) (12 pages) doi:10.1115/1.4006650 History: Received June 27, 2011; Revised February 17, 2012

Studying the vibrational characteristics of guided circular saws is of particular interest in the current study. Guided circular saws are free in both the inner and outer rim. They are restrained from having axial motion by using two space-fixed guide pads in either side of the blade. Because of the small clearance between the guide pads and the saw blade, the blade is capable of having rigid body tilting and a translational degree of freedom. At first, we attempted to develop an understanding regarding the vibrational characteristics of such disks through experimental investigations. An electromagnet was used to generate random white noise for the purpose of exciting the bending waves. Using inductance displacement probes, the frequencies and amplitudes of the disk vibrations were measured and the mean deflections were plotted. In the next step, a space-fixed external force (air jet) was used to excite the disks in the lateral direction. The experimental results indicate that the blade frequencies show a significant change as a result of the initial lateral displacement imposed by the external force. It was also seen that due to the presence of the external force, a stationary wave develops and collapses at a higher speed. For the numerical simulations, the nonlinear governing equations based on Von Kármán plate theory were used. The effect of rigid body degrees of freedom was taken into account. As an approximation, the guide pads were modeled with four space-fixed springs. Using Galerkin’s method, the governing equations were discretized and their equilibrium solutions were found. After linearizing the governing equations around the equilibrium solution, the effect of nonlinearity on the amplitude and frequency response of the guided blade was investigated. It was seen that the numerical results were in close agreement with the experimental results.

Copyright © 2012 by ASME
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References

Figures

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Fig. 1

Schematic of the experimental setup

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Fig. 2

Dimensions (in meters) and details of the experimental setup

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Fig. 3

Natural frequencies of blade #1 when it is only under the application of magnetic excitation

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Fig. 4

The mean deflection of blade #1 at the location of the inductance probes when it is only under the application of magnetic excitation

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Fig. 9

Natural frequencies of blade #1 when it is under both the air jet and magnetic excitations

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Fig. 8

The mean deflection of blade #3 at the location of the inductance probes when it is only under the application of magnetic excitation

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Fig. 7

Natural frequencies of blade #3 when it is only under the magnetic excitation

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Fig. 6

The mean deflection of blade #2 at the location of the inductance probes when it is only under the application of magnetic excitation

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Fig. 5

Natural frequencies of blade #2 when it is only under the application of magnetic excitation

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Fig. 12

The mean deflection of blade #2 at the location of the inductance probes when it is under the application of both air jet and magnetic excitations

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Fig. 11

Natural frequencies of blade #2 when it is under both the air jet and magnetic excitations

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Fig. 10

The mean deflection of blade #1 at the location of the inductance probes when it is under the application of both air jet and magnetic excitations

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Fig. 14

The mean deflection of blade #3 at the location of the inductance probes when it is under the application of both air jet and magnetic excitations

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Fig. 13

Natural frequencies of blade #3 when it is under both the air jet and magnetic excitations

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Fig. 16

The first mode shape of the stationary blade

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Fig. 17

Natural frequencies of the guided blade considering the effect of large deformations

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Fig. 18

A comparison between the numerical (taking into account the effect of large deformations) and experimental results for the blade mean deflection at the location of the 90 deg probe

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Fig. 15

(a) Natural frequencies and (b) real parts of the eigenvalues in the linear analysis

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