Acceptable Peak Temperature and Thermal Stress in Ti6Al4V … · 2018. 11. 22. · 2 ms, 100 Hz #4: not used Peak Average Temperature vs Time 0 50 100 150 200 250 300 0 100 200 300

Acceptable Peak Temperature and Thermal Stressin Ti6Al4V Target of ILC Positron Source

A. Ushakov1, S. Riemann2 and G. Moortgat-Pick1

1University of Hamburg, 2DESY

POSIPOL Workshop, CERN

3 September 2018

A. Ushakov (University of Hamburg) Temperature and Stress in Ti6Al4V Target POSIPOL, 3 September 2018 1 / 21

Outline

Deformation of Ti6Al4V targets by 14 MeV e− pulsed beam of theMainz Microtron

Stress-strain curves of Ti-alloy (Grade 5) at elevated temperatures

Plastic flow simulations in ANSYS above yield point (yieldstrength)

Allowed thermal stress at different temperatures

Summary


Targets and Used MAMI Electron Beam (March 2016)

#1: 1 mm thicknesswo thermal contact to holder

#2: 1 mm thicknesswith thermal contact to holder

#3: 2 mm thicknesswo thermal contact to holder

#4: not used

2 ms pulses, 100 Hz~18.5h of irradation

3 ms pulses, 67 Hz~4h of irradation

2 ms pulses, 100 Hz~14.5h of irradation

Electron beam for all targets:14 MeV, 50 µA during pulse, σ = 180 µm

Targets


Energy Deposition and Average Heating Power

Energy Deposition by Beam(FLUKA)

Average Heating PowerImported in ANSYS


Average Temperature vs Emissivity1 mm Target, 50 µA, 2 ms, 100 Hz

Temperature was measured by thermocouple at ≈ 5 mm distance from middle of thebeam.After switching beam on Tmeasured has achieved saturation level at T = 381◦C after6 min of irradiation.

Temperature vs Emissivity

0,5 0,6 0,7 0,8

400

450

500

550

600

650

T [°

C]

Emissivity

Tmeasured

Tmax

Temperature vs Time (ε = 0.7)

0 50 100 150 200 250 3000

100

200

300

400

500

600

T [°

C]

t [s]

Tmax

Tmeasured

Tmin


Peak Average Temperature of Different Targets

#1: 1 mm thick, therm. isolated

2 ms, 100 Hz

#2: 1 mm thick, with th. contact

3 ms, 67 Hz

#3: 2 mm thick, therm. isolated

2 ms, 100 Hz

#4: not used

Peak Average Temperature vs Time

0 50 100 150 200 250 3000

100

200

300

400

500

600

700

T [°

C]

t [s]

1 mm thickness, isolated 1 mm thickness, with contact 2 mm thickness, isolated


Deformation of Targets

No visible deformation

on back side of target 1

No visible deformation

on both sides of target 21mm

Target 1: front side

Target 3: front side

500�m

Target 3: back side

Peak hight: ~15 µm1mm

(front side)

Can ANSYS be used for the prediction of target deformation?


Thermal Cycles and Temperature Distributions2 mm Target, 50 µA, 2 ms, 100 Hz, ε = 0.7

At End of Thermal Cycle At End of Pulse


Data on Stress-Strain Curves

0

40

80

120

160

200

240

280

0 4 8 12 16 20

Strain, 0.001 in./in.

Str

es

s,

ksi

RT

700 °F

400 °F

-423 °F

-321 °F

-110 °F

900 °F

MIL-HDBK-5H

1 December 1998

M. Kopec et al., DOI:10.1016/j.msea.2018.02.038

[MIL-HDBK-5H]: Military Handbook “Metallic materials and elements for aerospace vehiclestructures”, MIL-HDBK-5H, 1 December 1998, 1651 pp.

[Kopec]: M. Kopec et al., Materials Science and Engineering A 719 (2018) 72-81


Young’s Modulus


Multilinear Hardening


Coefficient of Thermal Expansion (MILHDBK5H)


Thermal “Cycle” Starting at 375◦C

0,000 0,005 0,010 0,015 0,0200

1x108

2x108

3x108

4x108

5x108

Eq. v

M S

tress

[Pa]

Eq. Total Strain [m/m]

375°C

1061°C

T"average" = 718°C

Highest equivalent von Mises stress in elastic region is 303 MPa


Distribution of Equivalent Stress



0,000 0,001 0,002 0,003 0,004 0,0050,0

4,0x107

8,0x107

1,2x108

1,6x108

2,0x108

2,4x108

Eq. v

M S

tress

[Pa]


T"average" = 813°C




0,000 0,001 0,002 0,003 0,004 0,0050,0

4,0x107

8,0x107

1,2x108

1,6x108

Eq. v

M S

tress

[Pa]


T"average" = 921°C



Maximum Allowed Thermal Stress and PEDD inTi6Al4V at Elevated Temperatures

Yield Strength and Max. ElasticEq. von Mises Stress vs Temperature

0 200 400 600 800 10000

200

400

600

800

[MIL-HDBK-5H,Kopec-2018]

(ANSYS Calculations)Max Equivalent von Mises Stress

Stre

ss [M

Pa]

Temperature [°C]

Yield Strength

Maximal PEDD vs Temperature

600 700 800 900 1000

240

280

320

360

400

440

480

520

PED

D [J

/(g p

ulse

)]

Average Temperature [°C]


Summary

Adding temperature dependent elasticity and hardening data to thematerial properties in ANSYS allows making estimations of temperatureand stress at which material starts to deform plastically.

Simulations have shown that the maximum equivalent stress ofelastically deformed by beam Ti6Al4V target is approx. 10% below theyield strength.

Transition from elastic to plastic deformation occurs at 600◦C averagetemperature when the equivalent von Mises stress reaches 400 MPa.

At higher temperatures the limits go down quickly, for example, at 800◦Caverage temperature: equivalent stress has to be < 200 MPa.

Further studies are needed to include impact of radiation damage andweakening of material caused by repeatedly applied loads (fatigue).


Many thanks to all people involved in "Target Experiments"

University Hamburg and DESYAlexander IgnatenkoGudrid Moortgat-Pick

Alena PrudnikavaSabine Riemann

University MainzKurt AulenbacherThomas Beiser

Philipp HeilValery Tyukin

Helmholtz Zentrum BerlinYegor Tamashevich

CFEL, HamburgAlexander KotheThorsten Uphues


Specific Heat


Transverse Beam Size

100 150 200 2500

5

10

15

20

25

30250 µm aperture radius

I targ

et [%

]

beam [µm]

0.06nA/0.36nA


Documents

Acceptable Peak Temperature and Thermal Stress in Ti6Al4V … · 2018. 11. 22. · 2 ms, 100 Hz #4: not used Peak Average Temperature vs Time 0 50 100 150 200 250 300 0 100 200 300