Thermo-Mechanical Models for the CLIC/LAB
Two-Beam Modules
Present Outcome & Future Prospects
22 February 2012
R. Raatikainen
Presentation outline
Introduction
A quick glance to the model configurations
Main differences in the thermo-mechanical model point of view
Modeling principles
Cooling scheme
Considered thermal and mechanical loads
Applied boundary conditions
Finite element model description - Towards more efficient modeling
Meshing definitions
Modeling interconnections
Results
Thermal results
Structural results
Summary
Conclusion & Future steps
LAB Module (Type 0-Type 0)
Lab module configuration to be
tested without the beam – RF
power dissipation is created via
heaters
Courtesy of D.
Gudkov
CLIC Two-Beam Module (Type 1)
Current CLIC two-beam
module configuration
(type 1), frozen for CDR
Courtesy of A.
Samoshkin
Cooling scheme in TMM
It should be noted that in TMM, cooling (mass flow) is applied only for the SAS, PETS and
waveguides. Thermal conditions for the DB Q, MB Q and loads can be addressed best by using
current input from the manufacture or performing CFD analysis separately. This approach is
done mainly in computational reasons.
Summary of the thermal dissipations in TMM
39 W
39 W
11W per WG
DB Q/ MB Q
PETS

WG
Maximum temperature variation of 5°C for the
mock-up magnet was considered (based on the
current reference value) – Courtesy of A. Bartalesi
DB
MB
SAS
820 W
(corresponding
to unloaded
operation)
Thermal condition for the loads in TMM
 Based on the 3D CFD cooling simulation performed earlier for the loads, the effect of the loads on the
module’s structural behavior was studied (only for the lab configuration)
 Loads were simplidied into cylinders and the thermal conditions were imported from FLUENT → 1st load
undergoes linear temperature variation of about 2.5°C compared to water inlet temperature of 35°C → the
surface temperature of the 4th load has thus its highest value of about 45°C
Boundary conditions
LAB module
CLIC module
Meshing definitons
 Most of the thin geometrical features are modelled as shells instead of solid shells or solids → Part of the
elements used in the model contains three d.o.f. (solids) and the other six d.o.f (shells) → Interconnections must
be created manually and taken into account in the APDL (Ansys Parametric Design Language) script as MPC
(Multibody Constraint, shell to solid interface)
 Both membrane and bending stiffnesses are taken into account for the shells (Reissner-Mindlin)
20-node
10-node
hetrahedral solid tetrahedral solid
element
element
4-node shell
element
3 d.o.f.s results into 3
force components
coupled
6 d.o.f.s results into 3 force and 2
momentum components
Total amount of nodes
about 3 million → over
15 million d.o.f.s !
Interconnections
 Two different techniques was tested for modeling the interconnections between module components;
equivalent cylinderical tube and ANSYS bushing joints, where the given stiffness coefficients are input as 6x6
matrix with 3 translational and 3 rotational parameters.
 Both techniques resulted in the same outcome (difference only few percents) but the equivalent tube
approach encountered several numerical problems → using a linear material model for such a thin (nanometer
scale) membrane results into large strains/stresses already in very low loading values.
500 MPa (with a force of
only few Newton!)
Low stiffness is lateral
direction
Ansys Bushing Joint:
Stiffness coefficients as a direct input (BOA
metal bellows cataloque)
+User does not need to use any elements when
defining the flexible contact
+The method is numerically very stable and
LINEAR!
+Allows the user to probe the forces (and
moments) directed to the bellows in different
load configurations.
Illustration: equivalent tube VS. Bushing joint
Structural behavior of the
bellows(equivalent tube)
under RF-load
Structural behavior of the
bellows(Bushing joint)
under RF-load. Smooth
behavior!
→In the future TMM configurations, an
alternative solution for the bellows could be
taken into account.
Thermal results – LAB module
Item
Max temp. of MB
Max temp. of DB
Water output temp MB
Water output temp DB
Value
43 ˚C
35.7 ˚C
34.8 ˚C
29.8 ˚C
Structural results – RF – LAB module
Environment at 25°C
x-direction
y-direction
z-direction
Item
Max. def. at MB line, RF
x
183 μm
y
8 μm
z
9 μm
Item
Max. def. at MB line, RF
(compact loads included)
x
189 μm
y
8 μm
z
10 μm
Structural results – RF – LAB module
Environment at 25°C
x-direction
y-direction
Item
Max. def. at DB line, RF
z-direction
x
46 μm
y
-8 μm
z
7 μm
Structural results – Vacuum – LAB module
Displacement in ydirection
Item
Max. def. at MB line, Vacuum
Max. def. at DB line, Vacuum
x
10 μm
2 μm
y
z
-27 μm 9 μm
130 μm 12 μm
Structural results – Gravity– LAB module
”drop” of the module, when
actuator stiffness (snake system)
is notified
Item
Max. def. at MB line, Gravity
Max. def. at DB line, Gravity
x
-5 μm
0 μm
y
z
-2 μm -26 μm
-4 μm -40 μm
Actual deflection < 6 µm
(actuator stiffness → ∞)
Thermal results – CLIC module
Item
Max temp. of the MB
Max temp. of the DB
Water output temp MB
Water output temp DB
Unloaded
42.5 ˚C
34˚C
35.0 ˚C
28.2 ˚C
Loaded
40.7 ˚C
34˚C
34.9 ˚C
28.2 ˚C
Structural results – RF – CLIC module
Environment at 30°C
x-direction
y-direction
Item
Max. def. at MB line, RF,
unloaded
Max. def. at MB line, RF,
loaded
z-direction
x
-45 μm
y
z
1.6 μm 15 μm
-38 μm
1.4 μm 12.4μm
Structural results – RF – CLIC module
Environment at 30°C
x-direction
y-direction
Item
Max. def. at DB line, RF
z-direction
x
15 μm
y
0 μm
z
6 μm
Structural results – Vacuum– CLIC module
Item
Max. def. at MB line, Vacuum
Max. def. at DB line, Vacuum
x
0 μm
3 μm
y
z
-130μm -4μm
53 μm 10 μm
Structural results – Gravity – CLIC module
”drop” of the module, when
actuator stiffness (snake system)
is notified
Item
Max. def. at MB line, Gravity
Max. def. at DB line, Gravity
x
0 μm
2 μm
y
z
-8 μm -22 μm
-10 μm -35 μm
Conclusion
 The temperature of the module in both configurations rises over 40°C due to the
RF-power dissipation
 The water temperature rise is about 10°C in MB and about 5°C in DB side at the
most
 Under RF heat dissipation, the structural deformation has significantly larger values
in the lab configuration (longitudinal about 180 µm) than in the CLIC configuration
(longitudinal about 45 µm) due to different supports/interconnections
The transversal defomation of the CLIC module from unloaded to loaded operation
is less than 3 µm
Vacuum created displacement are turning the beams towards each other. The
vacuum is not uniformly distributed especially on the DB side and thus, possible tilt in
the beam axis is seen. However, the vacuum created displacement could be further
studied by improving the supporting system and interconnections.
Under gravity load the module is ”dropped” about 20-40 µm. The actual deflection
of the RF structures can be calculated assuming infinite stiffness for the actuators.
Further studies
Comparative test results are required to verify the current results → Improved
understanding of the module’s thermo-mechanical behavior and its simulation model
can then be propagated to the following module generations
The current TMM has been numerically/technically significantly improved if
compared to the very first TMM version → As a next step, transient phenomena
could be studied more closely (e.g. What is the time required to reach fully steadystate thermal condition between unloaded and loaded operation for the module?
How the module acts in coupled transient thermal-structural enviroment (currently
possible in ANSYS 14.0)?
Furthermore, structural optimization should be considered →
What kind of supporting for the RF components including
interconnections would lead into a minimum deformation?
Other configurations...
Continuing TMM towards any transient/iterative cases
using a such complex model presented here requires still
signigicant computing resources – What is the work
needed vs. the gain? - As it best the model should be
considered to predict the very global response of the Test Module (type 1) – vacuum
reservoir replaced by minitanks
module.
Extra – Heat dissipation - LAB
4 x 11W for waveguides
Extra – Considered heat dissipation – CLIC (Type 1)
3 x 11W for waveguides
In loaded operation the total heat
for AS is 336W instead of 420W
Integrated total thermal dissipation along the beam
line per AS are about 410W and 336W for unloaded
and loaded operation, respectively