KOTO CsIカロリメータを地震から保護するカバーの設計と製作

Taku YamanakaSeptember 19, 2011

JPS Fall Meeting@Hirosaki

KOTO CsI Calorimeter

2240 2.5cm x 2.5cm

476 5cm x 5cm

50cm long CsI crystals

Finished stacking on Feb. 10, 2011

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J-PARC KOTOAt the earthquake on March 11, the CsI crystals moved out by ~5mm

3

Purpose of this project

Prevent the crystals from flying out of the cylinder at the NEXT large earthquake

Assumptions

1G horizontal acceleration

4.5g/cm3 x 50cm x 9.8m/s2 = 22kPa side pressure

x3 safety factor = 66kPa

(20t on 2m-diameter surface)

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Design Requirements

Strong

Light (no crane inside the dry room)

Soft (not to damage crystals)

Limited out-gassing in vacuum

V1 = to be used until the beam time

5

Hard plate?SS400 steel: strength = σmax = 2400kg/cm2

Required thickness = 2cm

weight = 490kg!

6

P = 66kPa

h

a

σmax =3(3 + ν)

8Pa2

h2

7

co /en

cushncfoss sa?rirn

IOuTen ylen/

,-. . .

Cover made of a strong cloth

Structure to keep parabola

shape

Soft cover

Tension and curvature - in case of a string -

8

T

T

θ2

θ1

x

z w [N/m]

Δx

w∆x = T (sin θ2 − sin θ1)

� T (dz

dx(x + ∆x)− dz

dx(x))

w � Td2z

dx2

Tension and curvature- in case of a sheet -

If the sheet has a parabola shape:

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Cushrutr

cforSSec,t'rtrn

outen ylerV

I

HI +:iJ;r'\,

Hh

Pz = ar2 = a(x2 + y2)P = 4aT

P∆x∆y = T∆y

�dz

dx(x + ∆x)− dz

dx(x)

�+T∆x

�dz

dy(y + ∆y)− dz

dy(y)

�

P � T (∂2z

∂x2+

∂2z

∂y2)

Material for the cover

T = 170kN/m

a = P/4T = 66kPa/ (4x170kN/m) = 0.1/m

bulges out 10cm + offset at the center

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weight(g/m2)

strength(N/m)

Kevlar Cloth T713 278 1.7x105

Kevlar Cloth T710 315 2.0x105

Teijin Technora MF1500 220 1.7x105

Teijin Technora MF1531 461 3.4x105

How to sew fabrics together

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and who would be even willing to do it?

Company for fabricating the cover

NI帝人商事 introduced 明大(株)

at Kurashiki, Okayama

http://www.meidai.co.jp/

Makes strong sling belts with Teijin Technora (~100t)

12

Strength test

Make a fabric loop with sewing

Insert two bars inside the loop

Press the two bars apart with force F

Tension = F/2

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F

5cm

14

15

Sample made by companyTension

~3kN/5cm

= 60kN/m

< 170kN/m (fabric strength)

16

17

The weft slip.Warp only

The weft are squeezed

Sewing thread push the weft

I tried many sewing methods18

19

SolutionMake dead ends for weft

20

10mm

SolutionMake dead ends for weft

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10mm

Tension ~ 100 kN/m

Final sewing method for Ver.1Bend two fabrics together in Z-shape

Sew 3 locations x 3 times w/ 3mm pitch

Tension = 100 kN/m = 0.6 x 170kN (fabric)

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DesignSew three 1m wide fabrics => 1 sheet

2 sheets at 45deg

Add sides for securing down to the cylinder

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The cover24

Securing the cover

Make a loop at the end, and insert a rope

The rope is hold by 9t x 44mm steel bars bolted down to the cylinder

25

idea by Ogahara@Meidai

co /en

cushncfoss sa?rirn

IOuTen ylen/

,-. . .

How to keep the parabola shape

26

27

co /en

cushncfoss sa?rirn

IOuTen ylen/

,-. . .

.(,

*0,

(!, '-brn, l^fls,) N (I,=ll7r !z'lzon")

xz +6##h" 4 d$t>ftR : !fute e"=)Ltt"(r

(eil(: ral-t 1t"tl7' VU'?SJ

7Ar/^,r

PVC pipes

2mm thick Polyethylene plates

Solution = Polyvinyl Chloride pipes

40 different types

379 pieces

28Mr. UesawaVice President

Kyoto Jushi-Seiko

29

30

31

5cm short!

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So we removed strings for half a circle, extended the side sheet by 7cm, and hand-sewed it.

33

34

Aug. 19, 2011 3AM= T - 6h

What we learned

Do not expect 1mm accuracy for fabrics

By sewing, fabrics takes min(L1, L2)

Prepare an length-adjustment mechanism for fabrics

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SummaryMade a cover to hold the CsI crystals under 1G horizontal acceleration.

Aramid cloths (Technora, Kevlar) are useful materials for such solutions.

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明大(株)　　　　　（縫製）NI帝人商事(株)　　（縫製社紹介）京都樹脂精工(株)　（塩ビパイプ切り）宮崎　　　　　　　（金属加工）秘書の亀井さん　　（ミシン貸し出し）浅川直也君(4年生)　（outgas試験)

Acknowledgements