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Shaft Dynamics Analysis

The document describes the first 10 modes of vibration from a finite element model of a rotating shaft. It lists the frequency and speed of each mode, and describes the type of vibration (bending, twisting). It also provides component specifications like material, weight, mass properties, and calculated deflections at load for the shaft components. Finally, it lists the critical speed of the shaft as 1,225 Hz or 73,513 RPM and cites the Rayleigh equation used to calculate it.

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111 views3 pages

Shaft Dynamics Analysis

The document describes the first 10 modes of vibration from a finite element model of a rotating shaft. It lists the frequency and speed of each mode, and describes the type of vibration (bending, twisting). It also provides component specifications like material, weight, mass properties, and calculated deflections at load for the shaft components. Finally, it lists the critical speed of the shaft as 1,225 Hz or 73,513 RPM and cites the Rayleigh equation used to calculate it.

Uploaded by

tooocoool
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as XLS, PDF, TXT or read online on Scribd
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Frequency Speed

Mode (Hz.) (RPM) Shape


1 46.5 2790 Bending at 0.25 Diameter Portion of Shaft
2 46.5 2790 Bending at 0.25 Diameter Portion of Shaft
3 71.6 4296 Twisting at Rotor/Magnets
4 78.6 4716 Bending in Middle of Shaft
5 78.6 4716 Bending in Middle of Shaft
6 279 16740 Twisting at Rotor/Magnets with Slight Bending in 0.375 Dia
7 289 17340 Bending in 0.375 Diameter Portion of Shaft
8 289 17340 Bending in 0.375 Diameter Portion of Shaft
9 456 27360 Twisting in the Middle of the Rotor/Magnets
10 579 34740 Complex Bending Mode
Note: Hexagonal Steel Portion of Rotor Considered part of the Shaft for Bending Calculations
Note: Deflections Calculated from Finite Element Model of Shaft with Individual Weights Applied

Weight Mass Deflection


Mass Component Material Volume Density Density Weight at Load
Spacer #1 Rynite 0.069 0.056 0.000145 0.0038 6.48E-09
Spacer #2 Brass 0.199 0.307 0.000795 0.0610 4.09E-06
Fiber Disks Asbestos 0.058 0.088 0.000228 0.0051
1.86E-06
Disk Carrier Steel 0.118 0.283 0.000732 0.0333
24 Magnets Neodymium 1.138 0.275 0.000712 0.3132 7.37E-06
Spring Stainless 0.009 0.280 0.000725 0.0025 4.51E-09
Resolver - 0.452 0.221 0.000573 0.1000 3.88E-06

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Critical Speed (RPM)


Critical Speed (Hz.)
73,513
1,225
= 187 .7
[ W 1 Y 1 +W 2 Y 2 +. . .+W n Y n
W 1 Y 21 +W 2 Y 22 +. . .+W n Y 2n ]
Note: Rayleigh Equation per Machine Design; Theory and Practice - Deutschman, Michels, Wilson
Macmillan Publishing Company; 1975
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+W n Y n
+W n Y 2n ]
hman, Michels, Wilson

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