Support Tube Dynamic Analysis

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Support Tube Dynamic Analysis

• KEKs ANSYS simulation
• model details
• Single Point Response Spectrum analysis
• SUGGESTED improvements
• beam model
• Harmonic Response Analysis
• Random Analysis
• Transient Dynamic Analysis (time domain)

E. Doyle 12/6/99
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KEK model constraints horiz rotations free, all
other d.o.f. fixed
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Four freq/displacement points used in KEK SPRS
analysis - analysis of max response to
transient event - damping accounted for in
response curve
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Beam Model - simply supported more efficient than
shell model
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Beam Model vs. Shell Model

• Natural frequencies in Hz

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Beam Model - cantilever
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Responses of Concern

• Differential motion between Q1 magnets
• Resulting from
• non-uniform ground motion at two ends
• structure asymmetry
• ANSYS can be used to explore these
• tube support dynamics
• benefit from joining two cantilevers (creation of
  common modes)

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Excitation Modes of Concern

• Harmonic - cultural sources
• Harmonic Response Analysis
• Random - natural and cultural sources
• Random PSD (power spectral density)
• Transient Analysis (time domain)

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Harmonic Analysis

• Sinusoidal excitation at specified ampl freq
• Response at magnet mount points
• Combine responses at all frequencies of interest

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Harmonic analysis - vert base motion, unit
amplitude
Different damping for the two beams
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Random Vibration Analysis

• Input PSD of base motion
• Result is PSD response at each magnet
• how to interpret?

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Absolute PSD Response ( 1m2/hz flat input)
--------- FREQUENCY
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PSD Response relative to base motion
--------- FREQUENCY
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Transient Dynamic Analysis

• Input sampled ground motion (time domain)
• Response is motion in time domain
• Combine in time domain (outside ANSYS)
• Generate cross correlation function (outside
  ANSYS)