1. Mechanical behavior of the EuroCirCol 16 T Block-type dipole magnet during a quench
Junjie Zhao, Tiina Salmi, Antti stenvall, Clement Lorin 1

2. Contents
1. Modelling
2. Simulated stress before quench and comparison with ANSYS (model validation)
3. Stress distribution due to temperature during a quench
4. Conlusions 2

3. Modelling Block design version v20ar, from C. Lorin 3 Parameter values
unit
Nominal current
11470 A
Operating field 16 T
Coils peak field
16.74
Operating temperature
1.9 K
Mid-plane shim
1.75 mm
LL magin (1.9K)
14.01 %
Outer diameter of dipole
338
Number of turns HF cable per layer
=30
Number of turns LF cable per layer
=74
Fx/Fy Lorentz force (per aperture)
10498/-5216
KN/m
Block design version v20ar, from C. Lorin 3

4. Department of Electrical Energy Engineering
Modelling
Contacts/symmetry:
sliding; 0.2 friction
glued: coils with pole vertically and with shoes
63 mm thick shell
750 µm ←
50 µm ↓
Department of Electrical Energy Engineering 4

5. (using a interpolation function)
Modelling
Mechanical modelling in comsol during a quench:
Temperature vs. time simulated in Coodi
Lorentz force vs. magnet current calculated from Roxie
Temperature and Lorentz force during a quench are read and introduced in Comsol
INPUT:
OUTPUT:
Temperature calculate in Coodi
results
(using a interpolation function)
Stress distribution
Lorentz force calculate in Roxie
Mechanical modelling 5

6. Modelling 6 Temperature calculated in Coodi
Lorentz force calculated in Roxie
Mechanical modelling
Temperature distribution without hotspot
Maximum Fx vs. current
Temperature distribution
Current decay and hotspot developement vs. time
Maximum Fy vs. current 6

7. Stress distribution before quench
Key
Cold – 4.2 K
Current 12000A
Comsol: von Mises
+121 MPa
+194 MPa
+187MPa
Key
Cold – 4.2 K
16.8 T (105% nominal)
(C. Lorin, Barcelona 2016)
Ansys: von Mises
+121 MPa
+196 MPa
+176MPa 7

8. Stress distribution before quench
Key
Cold – 4.2 K
Current 12000A
Comsol: X conponent
-135 MPa
-203 MPa
-200 MPa
Key
Cold – 4.2 K
16.8 T (105% nominal)
(C. Lorin, Barcelona 2016)
Ansys: X component
-135 MPa
-210 MPa
-196 MPa 8

9. Stress before quench 9

10. Stress before quench
The friction coefficient has little influence on the stress of the shell
The friction coefficient has more influence on the stress of the coil during the operation 10

11. Modelling during a quench
Normal case:( HT 356K)
The quench protection delay times take 40 ms and the hotspot occurs in the upper coil
The hotspot occurs in the bottom coil
Parametric study: The quench protection delay times take 50 ms . (HT 428K) 11

12. Dynamic stress
250ms
80ms
140ms
Current decay and hotspot developement vs. time
The peak stress is 206 MPa in both case, with and without hotspot (HT 356K upper coil)
In terms of peak stress, it is similar to without considering the hotspot (HT 356K upper coil) 12

13. Quench dynamic stress without hot spot
Max Von Mises stress distribution
50ms
80ms
140ms
+191 MPa
+195 MPa
+197 MPa
190ms
250ms
538ms
Quench dynamic stress without hot spot
+200 MPa
+204 MPa
+206 MPa
In terms of stress distribution, it is similar to cool down process after the quench 13

14. Quench dynamic stress with hot spot
Max Von Mises stress distribution
80ms
140ms
50ms
+193 MPa
+195 MPa
+197 MPa
Quench dynamic stress with hot spot
HS 356 K upper coil
190ms
538ms
250ms
+200 MPa
+204 MPa
+206 MPa
The peak stresses distribution are similar to the situation without considering the hot spot 14

15. Dynamic stress
In terms of peak stress, it is similar to quench dynamic stress without considering the hot spot (HT 356K bottom coil) 15

16. Quench dynamic stress with hot spot
Max Von Mises stress distribution
140ms
50ms
80ms
+191 MPa
+195 MPa
Quench dynamic stress with hot spot
HS 356 K bottom coil
190ms
+196 MPa
538ms
250ms
+199 MPa
+204 MPa
+207 MPa
The peak stress doesn’t occurs between the coils in the low field region 16

17. Dynamic stress
The peak stress occurring in the coil decided by the temperture distribution. 17

18. Stress distribution with hot spot (HS 428K upper coil)
Max Von Mises stress distribution
538ms
90ms
140ms
250ms
+196 MPa
+193 MPa
+204 MPa
+205 MPa
Stress distribution with hot spot (HS 428K upper coil) 18

19. Conclusion
It is possible to analyze the mechanical behaviour of the FCC magnet using Comsol
The friction coefficient has influence on the magnet peak stress, the friction coefficient between different components is needed
The Lorentz force and the thermal stress was considered during a quench
The peak stress behaviour is similar to consider the location of the hotspot occurring and the higher hotspot.
The stress distribution is decided by the temperature distribution without considering the hotspot 19