Some ESPI Measurements on the UK TM Stave Prototype

Static Out-of-plane deflectionsNormal Modes

Stave is mounted vertically to anAll-Indium panel with temperature sensors both sides

Distortion of panel measured due to temperature differential between sides60C differential gives ~8microns bend to panel

Capacitive displacement sensors watch front-face silicon in six locationsMounted to indium/aluminium bridges which attach to the indium panel

Cooling is supplied by blow-off CO2 system pipes and cables from rhsSmall (relatively) distortion arises on turn-on of cooling, which depends on strain-relief

Mounting and static-deflection set-up

Invar plate distortion with a ~45Clocal temperature differential front-back

Front Invar panel temperatures during cooling test reported

Rear Temperatures

Differential is never more than 6CInvar Panel is not driving movements in stave

This is the distortion in the stave caused by applying theCO2 gas back-pressure.

A continuous surface distortion ~10microns note that top left mounting was ‘incorrect’

Top 1 Top 3 Top 5

Bottom 2 Bottom 4 Bottom 6

The displacement sensors are located as shown:

A +ve displacement is movement away from sensor (into page)Conversely a negative is movement towardsLeft undisturbed the sensors readings remain stable to ~1m

When cooling or power is applied the stave moves in a waythat ESPI does not follow over extended periods (>2 seconds)Movement is jumpy?, but displacement sensors give ‘sensible’ readingsand after entire cycle return to same values within a few microns

Cooling offPower = 0Power = 120W

Cooling flow = 5Cooling on = 10

Data Run with sensor overlapping edges of Modules

TempTop Left Middle Right

Bottom Left Middle Right

Time in mins

Top 1 Top 3 Top 5

Bottom 2 Bottom 4 Bottom 6

motions relative to starting positions

Hard to believe theout-of-plane top left fixationis working ‘well’.

The ‘L’ shapes at the bottom edge line up with the edges of modules.When pressed these prove to be detached from the surface of the stave. This data is from 26/1/12 RUN 8 out of plane, when the gas pressure applied

Modules found to be debonded in some places

The ‘L’ shapes at the bottom edge line up with the edges of the 5th,6th,7th

modules from the lhs. When pressed these prove to be detached from thesurface of the stave. The module in ‘5th’ position from left moves by about 1/2mmThis data is from 26/1/12 RUN 8 out of plane, when the gas pressure applied

LLL

Modules found to be debonded in some places

Cooling offPower = 0Power = 120W

Cooling flow = 5Cooling on = 10

Data Run with sensor overlapping edges of Modules

TempTop Left Middle Right

Bottom Left Middle Right

Time in mins

Top Left Middle Right

Bottom Left Middle Right

Gas On

Liquid arrives

Cooling ExhaustedCooling Off

Time in minutes

Data run with sensors displaced to centre of modules

-40

-30

-20

-10

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80

sensor 1

sensor 2

sensor 3

sensor 4

sensor 5

sensor 6

1 3 5

2 4 6

Sensor 1 – silicon middle in from edgeSensor 2 – silicon middle in from edgeSensor 3 - carbon fibre just off moduleSensor 4 – silicon middle edge of moduleSensor 5,6 unchanged

Cooling

P=120W

Cooling off

P=0W

Carbon measure maybe affected by proximityto edge of stave - will check

At location 4silicon seems to bewell bonded by visual inspection

Example of movement in 1.2s during period before liquid arrives after cooling is turned on, but before liquid arrives at stave. [?tbc]

Example of change in 1.2s during period when P=60W

Example of change in 0.8s during period when P=60W

It is possible that parts are still moving too fast to see at all.Jumps seem another possibility.

NB the invar baseplate moves and this is a clear uniform motion(but over much longer time scales than 1.2s) - not at all similar to the apparent behaviour of the stave.

Updated Conclusions on Static behaviour

o Stave Movement during cooling/powering is typically less than 50m out of plane repeatable to within ~fewm [possibly measurement limitation] Is smooth when the gas pressure applied – surface visible with ESPI Modules are apparently not well bonded ‘locally’ to the stave, causing

spurious measurements and ESPI difficultyo Cold-unpowered to cooled is biggest changeo Applying power brings the stave partially back to uncooled stateo No evidence yet that single edge mounting contributory to size of movement

(both edges seem to move the same way & same distance ?)

Stave excited with sound

900W amplifier, 2 x 300W speakers [one used as table]Estimate <100W sound delivered from a range of 1.5m

Note that wavelength of sound at 60Hz is around 5m240Hz will be <1.5m

This is not an ideal excitation method

1st mode

2nd mode

3rd mode

Mode shapes expected if the stave is mounted in a standard configuration and without any loose contact at the locks

f2 / f1 = 1.24; f3/f2 = 1.27

104Hz

164Hz

Measurement with loose top left (bottom right!) mount(Using different speakers)

FEA

FEA

FEA

1st mode

2nd mode

3rd mode

f2 / f1 = 1.24; f3/f2 = 1.27

Freq 107.76

Approx 60Hz

Measurement with top left fixation tight (bottom right in below)

~60Hz

108Hz

above 118Hz

Stave exhibits other modes, eg:

The Q of the stave seems high, resonances have a width <4HzQ is probably >20

Early Conclusions on Resonant Behaviour

o Stave exhibits resonant behaviour similar to ‘basic’ FEA expectationo Lowest resonance is ~58Hz in current mounting schemeo Q is higho Behaviour is quite complicated

Approx 118Hz

Freq above 118Hz

Freq definitely 118.71Hz

Freq >120Hz

Freq 86Hz

Freq 107.76