pre-isolator & qd0 support modeling 5th wg5 meeting f. ramos, a. gaddi, h. gerwig, n. siegrist...
TRANSCRIPT
Pre-isolator & QD0 support modeling5th WG5 Meeting
F. Ramos, A. Gaddi, H. Gerwig, N. Siegrist
September 7, 2010
Layout
1Presented by H. Gerwig at the 15th MDI Meeting – 16/07/10 | Drawings by N. Siegrist
FE Model Layout
2
Things missing in the model:• Pre-alignment mechanics• Final doublet’s geometries (using, for now, 3-D point masses with estimated inertias)• Final doublet’s supporting structures (girders, etc.)• Pre-isolator’s supports (using , for now, 1-D springs with appropriate stiffnesses)
Lumical Beamcal QD0 SD0 MULT QF1 SF1
QD0 Support tube
3
The tuning of the tube´s eigenfrequencies led to the reinforced polygonal cross-section shown
630
493
Assumptions of the FE model
4
• The pre-isolator mass is assumed to be made out of concrete and the remaining parts of stainless steel;
• The QD0’s yoke mass is supported by the inner tube while the coils’ mass is supported by the outer tube;
• Mass of the remaining elements extrapolated from QD0’s mass;
• Spring stiffness's tuned to yield fundamental eigenfrequencies of 0.7Hz and 1Hz in the horizontal and vertical directions respectively;
Main vibration modes
5
Mode #
Frequency [Hz]
1 0.422 0.493 0.704 0.705 0.796 1.007 14.298 21.699 22.08
10 33.5311 45.0312 51.1913 61.6714 63.6115 69.7416 70.6817 70.7818 77.1319 89.5620 105.57
Harmonic excitation in the vertical direction
6
Vertical steady-state response at QD0
1 Hz
51.2 HzGood performance above the first resonance peak
Harmonic excitation in the horizontal directions
7
Vertical steady-state response at QD0
0.05
0.32
There is a good decoupling between the
different directions
Out-of-phase vertical excitation
8
GOAL: Assess the impact of non-coherent ground motion
UY=sin(ωt-90)
UY=sin(ωt)
UY=sin(ωt+90)
9
Out-of-phase vertical excitationVertical steady-state response at QD0
0.49 Hz
Good performance despite the “lever arm” effect
10
Random vibration response
1 10 100Hz
OOR
OOR
OOR
OOR
1000z
10a
100a
1000a
10f
100f
1p
10p
((m)²/Hz)
GP_Ref (V)GP (V)
Ground motion measurements at CMS (A. Kuzmin – EDMS 1027459)
Vertical ground motion @ YB0
Random vibration response
11
Vertical ground motion @ CMS-YB0
Vertical motion @ QD0
Random vibration response
12
Vertical ground motion @ CMS-YB0
Vertical motion @ QD0
4 Hz
2.9 nm
0.1 nm
Reduction in r.m.s. displacements by a factor 30 above 4 Hz
Summary• A detailed FE model of the pre-isolator and support tube was created;
• The main eigenfrequencies where chosen to be 0.7Hz and 1Hz in the horizontal and vertical directions respectively, to match the specifications of commercially available mounts;
• QD0’s support tube was tuned to have an eigenfrequency around 50Hz (51.2Hz);
• The harmonic analysis shows the system’s good vertical isolation performance above the first resonance peak while assuring a good decoupling between the different directions;
• The random vibration analysis confirms the good performance of the system, yielding a reduction by a factor 30 in r.m.s. displacements above 4Hz;
•The model will need to be improved with the addition of detailed geometry for the magnets, forward calorimeters, supporting girders, pre-alignment mechanics, etc. . 13
Spare Slides
Mode #1 Mode #2
Mode #3 Mode #4
Mode #5 Mode #6
Mode #7 Mode #8
Mode #9 Mode #10
Mode #11 Mode #12
Mode #13 Mode #14
Mode #15 Mode #16
Mode #17 Mode #18
Mode #19 Mode #20
Harmonic excitation in the vertical directionSteady-state response at QD0 in the transversal direction
Steady-state response at QD0 in the beam direction
Harmonic excitation in the horizontal (transversal) directionSteady-state response at QD0 in the transversal direction
Steady-state response at QD0 in the beam direction
Harmonic excitation in the horizontal (beam) directionSteady-state response at QD0 in the transversal direction
Steady-state response at QD0 in the beam direction
Random vibration response at QD0Excitation in the transversal direction
Excitation in the beam direction
Ground motion @ CMS-YB0
Vertical directionBeam directionTransversal direction
Ground motion @ CMS-YB0
Vertical directionBeam direction
Transversal direction