pre-isolator update
DESCRIPTION
Pre-isolator Update. 18 th MDI Meeting. F. Ramos, A. Gaddi, H. Gerwig, N. Siegrist. December 17, 2010. “State of the art” update. Yet a nother great example of a pre-isolator . IBM/ETH Nanotechnology Center – Zurich Due to be completed by the spring of 2011. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/1.jpg)
Pre-isolator Update18th MDI Meeting
F. Ramos, A. Gaddi, H. Gerwig, N. Siegrist
December 17, 2010
![Page 2: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/2.jpg)
“State of the art” update
Mechanical vibrations requirements: Velocity less than 500 nm/s (x,y,z), below 16 Hz and less than 100 nm/s above the 16 Hz band.
Description:• Separated tool platform vibro-acoustically decoupled from building and operator platform;• Massive concrete pedestal (> 65 tons), suppressing frequencies above 25 Hz;• Tool platform with passive mechanical damping, suppressing frequencies above 3 Hz;• Active mechanical damping down to 0.5 Hz;• Operator platform decoupled from tool platform.
IBM/ETH Nanotechnology Center – ZurichDue to be completed by the spring of 2011
Yet another great example of a pre-isolator
2
![Page 3: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/3.jpg)
Quick look at the numerical simulations of the pre-isolator’s performance
(LCD Note 2010-011)
3
![Page 4: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/4.jpg)
FE Model Layout
Things missing in the model:• Pre-alignment mechanics• Final doublet’s geometries (using, for now, lumped 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
4
![Page 5: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/5.jpg)
Harmonic excitation in the vertical direction
Vertical steady-state response at QD0
1 Hz
51.2 Hz
Good performance above the first resonance peak
Main eigenfrequency(design)
Inner support tube(tunned)
5
![Page 6: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/6.jpg)
Harmonic excitation in the horizontal directions
Vertical steady-state response at QD0
0.05
0.32
There is a good decoupling between
the different directions
6
![Page 7: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/7.jpg)
Test set-up @ Point 5(ongoing work)
7
![Page 8: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/8.jpg)
Goals of the test
Validate the results from the finite element model
8
Assess the influence of external perturbations in a noisy environment (workshop floor)
Check for energy loss mechanisms (friction, plastic deformation,...)
Evaluate the performance of a real systemwith the pre-isolator’s characteristics (heavy mass and low natural frequency)
+
+
=
![Page 9: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/9.jpg)
9
40 ton dead-load
4 tapered steel beams
4 flexure hinges
Support beams
![Page 10: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/10.jpg)
Static Deformation
203 to 205 mm
205 mm
The measured static deformation matches (within 1%) the results from the finite element model.
10
![Page 11: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/11.jpg)
Vertical direction – Center dead-load/support beam
1.1Hz 6Hz
12Hz
A. Slaathaug – EN/MME
11
• First resonance peak at 1.1 Hz (very close to the pre-isolator’s design goal of 1 Hz);
• Good behavior up to 5 Hz;
• Amplitude decreasing with ~1/ω^2 between 1.5 Hz and 5 Hz indicates very low damping of the set-up (below 1%);
• Above 5 Hz, higher order resonance peaks appear and degrade the performance of the set-up;
WHY?
Dynamic Performance
![Page 12: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/12.jpg)
New simulations
12
using a detailed model of the set-up
![Page 13: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/13.jpg)
Eigenfrequencies and Eigenmodes1.1Hz 6.7Hz
17.8Hz 57.2Hz
*Main vibration modes 13
![Page 14: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/14.jpg)
Harmonic response in the vertical direction
• Vibrations in the longitudinal direction induce significant movement in the vertical direction (not the case for the actual design of the pre-isolator);• Must combine the two effects to get an accurate representation of the set-up. 14
1
Vertical direction – Center of dead-load/ground (excitation in the vertical direction)
Vertical direction – Center of dead-load/ground (excitation in the longitudinal direction)
![Page 15: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/15.jpg)
Vertical direction – Center of dead-load
Combined harmonic response in the vertical direction
+
A. Slaathaug – EN/MME
• Good match at frequencies up to 50Hz 15
Combine
Simulated
Measured
![Page 16: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/16.jpg)
Harmonic response in the longitudinal direction
A. Slaathaug – EN/MME
• Good match at frequencies up to 40Hz.16
Longitudinal direction – Support beam/ground (excitation in the longitudinal direction)
Simulated
Measured
![Page 17: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/17.jpg)
Harmonic response in the vertical direction
• The model doesn’t match the measure data above 40Hz.
A. Slaathaug – EN/MME
17
Vertical direction – Support beam/ground (excitation in the vertical direction)
Simulated
Measured
![Page 18: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/18.jpg)
Summary of things to address
dead-load not “rigid” Flexure
hinges added
Support structure not “rigid”
±50 mm
A. Slaathaug – EN/MME
18
Not valid if the dead-load isn’t “rigid”
Additional higher order eigenfrequencies
Insufficient stiffness in the longitudinal direction
Uncertainty in the position of the sensors
![Page 19: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/19.jpg)
Proposed changes
• Replace the steel supports by concrete blocks ;• Add 4 sets of horizontal stiffeners to improve the longitudinal stiffness of the set-up;• Change the distribution of the steel blocks that make up the dead-load to improve its internal natural frequency. 19
![Page 20: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/20.jpg)
+
Expected improvements
1.1Hz
1.3Hz
6.7Hz17.8Hz
57.2Hz
8.7Hz
31.5Hz
72.7Hz
20Isolation
Initial design
New design
![Page 21: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/21.jpg)
Summary (1)• When compared with the initial simulations, the first set of measurements made on the pre-isolator test set-up showed unexpected results in the mid to high frequency range;
• A refined F.E. model was created and the results match much better the measured data in low to mid range frequencies;
• High frequency data calculated using the average between sensors might not be usable due to the relatively low internal eigenfrequencies of the dead-load;
21
![Page 22: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/22.jpg)
Summary (2)• New measurements will be performed with a sensor placed at the center of the “dead load”, concrete blocks as a support to the set-up and horizontal stiffeners in the longitudinal direction;
• The good performance of the set-up at low frequencies is promising. Nevertheless, it should be acknowledged that this design, with its several high frequency modes, is not representative of the future final design of the pre-isolator.
22
![Page 23: Pre-isolator Update](https://reader036.vdocuments.us/reader036/viewer/2022062222/568164f6550346895dd76287/html5/thumbnails/23.jpg)
News• Following Holland@CERN exhibition, contacts were established with TNO Science & Industry;• They developed a 6 DOF passive/active vibration isolation table top (Kolibrie); • Includes innovations in sensor technology and placement.
Current performance (transmissibility)
Passive
Passive+active
23