Upload
quentin-long
View
229
Download
11
Tags:
Embed Size (px)
Citation preview
Support Tube Dynamic Analysis
• KEK’s 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
KEK model constraints
horiz rotations free, all other d.o.f. fixed
Four freq/displacement points used in KEK SPRS analysis
- analysis of max response to transient event
- damping accounted for in response curve
Beam Model - simply supported
more efficient than shell model
Beam Model vs. Shell Model
• Natural frequencies in Hz
Mode# KEK SLACvert 1 61.7 62.1
2 70.0 78.8horiz 1 61.9 74.2
2 70.2 91.2
Beam Model - cantilever
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)
Excitation Modes of Concern
• Harmonic - cultural sources– Harmonic Response Analysis
• Random - natural and cultural sources– Random PSD (power spectral density)– Transient Analysis (time domain)
Harmonic Analysis
• Sinusoidal excitation at specified ampl & freq• Response at magnet mount points
• Combine responses at all frequencies of interest
Harmonic analysis - vert base motion, unit amplitude
Different damping for the two beams
Random Vibration Analysis
• Input PSD of base motion
• Result is PSD response at each magnet
• how to interpret?
Absolute PSD Response
( 1m2/hz flat input)
--------- FREQUENCY
PSD Response relative to base motion
--------- FREQUENCY
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)