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PowerPoint Slides: Webinar_29_stress_velocity.pptx

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Acceleration Time History: Time (sec) & Accel (G) srs1000G_accel.txt

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References:

Stress-Velocity Relationship: sv_velocity.pdf

Bending Frequencies of Beams, Rods, and Pipes: beam.pdf

Modal Transient Vibration Response of a Cantilever Beam Subjected to Base Excitation: cantilever_modal_transient_base.pdf

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Matlab script: Vibrationdata Signal Analysis Package

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See also:

Vibrationdata Webinars

Dr. Howard Gaberson’s Papers

Thank you,

Tom Irvine

PowerPoint Slides:  Webinar_28_mdof_SRS.pptx

Audio/Visual Files:

MDOF_SRS_1.wmv

MDOF_SRS_2.wmv

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Acceleration Time History:  Time (sec) & Accel (G)    srs2000G_accel.txt

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References:

Two-Stage Isolation for Harmonic Base Excitation: two_stage_isolation.pdf

Shock Response of Multi-degree-of-freedom Systems: mdof_srs.pdf

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Matlab script: Vibrationdata Signal Analysis Package

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See also:

Vibrationdata Webinars

Thank you,

Tom Irvine

Wire rope damping depends on:

1. Material
2. Diameter
3. Length
4. Number of strands
5. Number of turns per length
6. Initial tension or preload
7. Displacement amplitude

The damping can be very nonlinear, particularly depending on displacement amplitude.

The flexing of wire rope involves both coulombic and viscous damping. At very low vibration levels, the wire strands stick together and little sliding occurs. The damping is low and the behavior is viscous.

With higher displacements, coulomb damping predominates as the wires break free and start to slide against each other, absorbing large amounts of energy.

At large displacements the bending and stretching of the wire strands overshadows the sliding friction and viscous behavior again starts to show.

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Here are some viscous damping values for straight cables.

Longitudinal Vibration for 10 mm (0.39 inch) diameter:
Damping = 0.7% to 2.0% (ref 1)

Transverse Vibration for 3/8 inch diameter:
Damping = 0.3% to 0.5% (ref 2)

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For the case of wire rope used in helical isolators, the damping can vary from 5% to 22% (ref 3).

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Wire Rope Isolation of a Camera Video

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References

1. Feyrer, Wire Ropes: Tension, Endurance, Reliability

2. Vanderveldt, Chung and Reader, “Some Dynamic Properties of Axially Loaded Wire,” Experimental Mechanics, 1973.

3. http://www.enidine.com/Industrial/WireFAQmain/#14

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See also:
http://sem-proceedings.com/24i/sem.org-IMAC-XXIV-Conf-s02p04-Modal-Damping-Estimates-from-Static-Load-deflection-Curves.pdf

Initial investigations into the damping characteristics of wire rope vibration isolators

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- Tom Irvine

This Webinar covers two synthesis techniques

1. Wavelets
2. Damped Sinusoids

PowerPoint File:

webinar_27_SRS_synthesis.pptx

Audio/Visual Files:

1. SRS Synthesis Wavelets.wmv
2. SRS Synthesis Damped Sines.wmv

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Matlab script: Vibrationdata Signal Analysis Package

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See also:

Vibrationdata Webinars

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If you would like to be included on the distribution list for the Webinar series, please send an Email to: tom@vibrationdata.com

Thank you,

Tom Irvine

This Webinar has two topics:
1. Aliasing in shock data
3. Saturation and spurious trend removal

PowerPoint File:

webinar_26_pyrotechnic_shock_part2.pptx

Audio/Visual File:

Pyrotechnic_Shock_Response_Part_2.wmv

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Data:

rv_separation_raw.txt – time (sec) & accel (G)

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Matlab script: Vibrationdata Signal Analysis Package

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See also:

Anthony Chu Accelerometer Zeroshift Paper

Vibrationdata Webinars

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If you would like to be included on the distribution list for the Webinar series, please send an Email to: tom@vibrationdata.com

Thank you,
Tom Irvine

sdof_base_image

Rainflow fatigue cycles can be easily calculated for a single-degree-of-freedom subjected to a sine or sine sweep base input.  The reason is that each pair of consecutive positive and negative response peaks forms a half-cycle.

The relative fatigue damage can then be calculated from the rainflow cycles.

Here are Matlab scripts for performing the rainflow and damage calculations.  rainflow_sine.zip

rainflow_sine.m is for the case where the natural frequency is known.

rainflow_sine_fds.m gives the fatigue damage spectrum for a family of natural frequencies.

The remaining scripts are supporting functions.

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See also: 

Rainflow Cycle Counting

ramp_invariant_base.pdf

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- Tom Irvine

PowerPoint File:

webinar_25_pyrotechnic_shock.pptx

Audio Visual File:

pyrotechnic_shock_response.wmv

Alternate link:  pyrotechnic_shock_response.wmv

YouTube Version

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Data:

rv_separation.dat – time (sec) & accel (G)

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Matlab script: Vibrationdata Signal Analysis Package

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See also:

Delta 4 Heavy Launch

Vibrationdata Webinars

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- Tom Irvine

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