1. 7E: Tower test plans GLAST Large Area Telescope: Tracker Subsystem
Gamma-ray Large Area Space Telescope
GLAST Large Area Telescope: Tracker Subsystem
7E: Tower test plans
Nicola Mazziotta University and INFN Bari - Italy

2. Outline Overview Tower vib plan Tower thermal plan Test schedule
Summary
Reference LAT Documents:
LAT-MD-00408, LAT Instrument Performance Verification Plan
LAT-SS-00788, LAT Environmental Specification
LAT-TD-01005, Thermal Test Results on Thick Converter Mock-up Trays
LAT-TD-01249, Thermal Test Results for Pre-Engineering Model Trays
LAT-PS-01584, LAT Tracker Tray SSD Ladder Panel Assembly Procedure
LAT-TD-00155, Tower Vibration Test Plan
LAT-TD-01840, Tower Thermal Test Plan

3. Tower matrix Item Quantity High freq sine Sweep 20-2000 Hz
Random Vibration
White noise
Low freq sine Sweep
5-50 Hz
Functional
Thermal Vacuum
Test site
Tower A (Qual) 1
X,Y,Z axis
Qual 
Italy
Tower B (Spare)
Acc
1-16 Towers (Flight) 16

4. Qual test flow (LAT-MD-408)

5. Acc test flow (LAT-MD-408)

6. Low frequency sine sweep
Tower vib levels
Low frequency sine sweep
White Noise
Frequency
(Hz)
ASD WN
Level(g2/Hz)
Overall
grms
Duration
(min)
20 ÷ 2000
10-4
0.45 1
Random vibration
Frequency
(Hz)
ASD Acceptance
Level (g2/Hz)
ASD Qualification 20
0.01
0.02
20-50
+5.9 dB/oct
50-800
0.06
0.12
-5.9 dB/oct
2000
Overall
8.7 grms
12.3 grms
Duration
1 min/axis
2 min/axis
High frequency sine sweep
Frequency
range
20  2000 Hz
Sweep rate
2 oct/min
Target
Amplitude
0.5 g0-pk

7. Tower vib set up Accelerometers set up (TBR):
3 axial on the shaker table (control accelerometer)
3 axial on the center of the bottom tray lower surface
3 axial on the center of the top tray upper surface
3 axial accelerometer +X sidewall center of the thermal boss tray number 12;
3 axial accelerometer +Y sidewall near the center of the tray number 10;
3 axial accelerometer +Y sidewall center of the thermal boss of the tray number 1;
3 axial accelerometer +Y sidewall center of the thermal boss of the tray number 19;
3 axial accelerometer -X sidewall center of the thermal boss of the tray number 10;
3 axial accelerometer -Y sidewall near the center of the tray number 10, on the center plane;

8. Tower A vib sequence For each axis Step Description Test Level LPT 1
LPT 1
Mounting 2
Fixture calibration
High frequency sine sweep
0.5 g0-pk 3
Normal mode search 4
Pre-random vibration
White noise
0.45 grms 5
Random vibration
-6 dB Qual 6
Post/Pre-random vibration 7
-3 dB Qual 8 9
0 dB Qual 10
Post-random vibration 11
Normal mode check 12 13
Low frequency test
Low frequency sine sweep
Qual 14
Dismounting 15 16
Test completion

9. B&Flight Towers vib sequence
For each axis
Step
Description
Test
Level
LPT 1
Mounting 2
Fixture calibration
High frequency sine sweep
0.5 g 0-pk 3
Normal mode search
0.5 g0-pk 4
Pre-random vibration
White noise
0.45 grms 5
Random vibration
-6 dB Acc 6
Post/Pre-random vibration 7
-3 dB Acc 8 9
0 dB Acc 10
Post-random vibration 11
Normal mode check 12
Dismounting 13 14
Test completion

10. Tower A thermal levels 8 Cycles Thermal-Vacuum cycling/Qual level
Ranges
-30°C  50°C
# of cycles
8 (12)
Temp. rate
20°C/hr
Pressure
10-5 Torr
extreme
12 hr
Total Duration
256 (384) hr + T room
8 Cycles
(Tab. 2 LAT-MD-408)

11. B&Flight Towers thermal levels
Thermal-Vacuum cycling/Acc level
Ranges
-20°C  35°C
# of cycles 4
Temp. rate
20°C/hr
Pressure
10-5 Torr
extreme
4 hr
Total Duration
54 hr + T room

12. Tower covered with a thermal blanket during T-V cycles.
Tower thermal set up
Tower covered with a thermal blanket during T-V cycles.
The tower has a large number of thermocouples in the read out cables that can be acquired by using the TKR DAQ system.
Additional thermocouples (TBR):
+Y sidewall center of the thermal boss of the tray number 1;
+X sidewall center of the of the tray number 1, on the center plane;
+Y sidewall center of the thermal boss of the tray number 19;
+X sidewall center of the of the tray number 19, on the center plane;
-X sidewall center of the thermal boss of the tray number 10;
-Y sidewall near the center of the tray number 10, on the center plane
The temperature control point for the cold part of the cycle will be the coldest thermocouple, while the control point for the hot part of the cycle will be the hottest one.

13. Tower thermal sequence
Step
Description
Level
CPT 1
(Strain gauges and) Thermocouple set up 2
Chamber set up 3
(Strain gauges calibration) 4
Thermal vacuum cycles  CPT/LPT
Qualification/Acceptance CPT/LPT 5
Dismounting 6 7
Test completion

14. Summary Work in progress: Number of thermal qualification cycles
LPT definition
CPT definition
Use of strain gauges for T-V test ???