The document describes a study of the temperature distribution and structural deformation of a dashboard surface subjected to direct sunlight. The study involves creating models of the dashboard made of polypropylene and steel in Abaqus. Both materials are subjected to convection heating from the vehicle interior and a 400 W/m2 heat flux to simulate sunlight. The results show that while steel distributes heat more uniformly, polypropylene reaches lower maximum temperatures. Both materials experience strain from the thermal loading, but steel exhibits lower displacement and higher stresses at constraint points due to its higher modulus of elasticity. However, using steel for a 2.5mm thick dashboard would compromise flexibility.

1. Vizzini Simone

2. Description of the problem
The task of the exercise is to study the:
• temperature distribution
• the structural deformation of the dashboard
surface when part of it is subjected to direct sun
light.
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3. Description of the problem
Material
used:
Polypropylene
E [Gpa]
ν
1.8
0.45
ρ
[kg/m3]
946
Thermal
Expansion
coefficient [1/C°]
Thermal
Conductivity
[W/mC°]
Heat
Transfer
coefficient [W/m2C°]
150 e-6
0.16
25.4
73
40
Steel
210
0.3
7800
1 e-5
Dashboard property:
– thickness t= 2.5 mm
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4. Description of the problem
Loading condition.
It is suggested to reach the target following some
intermediate steps:
• to obtain the temperature on the dashboard due to
convection with the inner temperature of the cockpit,
• to apply a heat flux of 400 W/m2 to part of the
dashboard in order to simulate the sun light (heat flows
in the dashboard material by conduction),
• to define a coupled thermo-structural analysis and to
analyse the stress/strain distribution on the dashboard.
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5. Creation of the model
Import the geometry
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6. Creation of the model
Move some surface from dashboard to air tunnel
– [tool-organize]
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7. Creation of the model
Create the Material and insert the specific
properties
– [card image:MAT1 and MAT4 for thermal properties]
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8. Creation of the model
Create the “Properties” and assign to the
components
• [card image:PSHELL, choose the material and define
the thickness]
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9. Creation of the model
Create the mesh and merging the common
nodes
– [2D-automesh, tool-edges]
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10. Creation of the model
Create the constraint point
– create the master nodes [geom-nodes]
– connect to the dashboard [1D-rigids]
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11. Creation of the model
Create the convection heat exchange surface
– [analysis-interfaces]
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12. Creation of the model
Create the internal heat source, creating a
constraint node with the specific initial T and
assign to to the dashboard
– [geom-node, analysis-constraint, card edit-insert the
inner T ]
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13. Creation of the model
Constraint all the air-tunnel nodes and assign
the initial T
– [analysis-constraints, card edit-insert the T ]
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14. Creation of the model
Create the load-step and Simulate
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15. Creation of the model
Create the conduction heat exchange surface,
create the flux, update the loadstep adding the
flux to the laod and Simulate
– [analysis-interfaces]
– [analysis-flux]
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16. Creation of the model
Create the constraints for the master nodes.
– [analysis-constraints]
Create a generic load-step for the thermal stress
Simulate
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17. Results
Temperature due to convection with
dashboard made of polypropylene
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18. Results
Temperature due to convection with
dashboard made of steel
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19. Results
Temperature due to convection and sun light
with dashboard made of polypropylene
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20. Results
Temperature due to convection and sun light
with dashboard made of steel
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21. Results
Strain distribution due to convection and
sunlight with dashboard made of polypropylene
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22. Results
Strain distribution due to convection and
sunlight with dashboard made of steel
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23. Results
Stress distribution due to convection and
sunlight with dashboard made of
polypropylene
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24. Results
Stress distribution due to convection and
sunlight with dashboard made of steel
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25. Results discussion
Temperature due to convection:
– in both cases, polypropylene and steel, we can see
that the temperature of the dashboard achieved
without the sunlight is 30 C , i.e. the internal
temperature, except for some points in the
polypropylene simulation that achieve a slightly
higher temperature due to maybe a simulation
errors. The difference in the two cases is the
temperature field near the air-tunnel. Because of
the steel has an higher thermal conductivity we can
see an bigger aerea with a temperature ranging
from 10 C (air-tunnel T ) and 30 C (internal T ),
while with poly this boundary area is very limited.
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26. Results discussion
Temperature due to convection and sun-light:
– again, like in the previous simulation, we ca see
that the steel is better in distribute the heat in the
all surface. the temperature distribution is more
uniform and we have a maximum value of 39 C
– in the poly dashboard the sun light tends to
increase, up to 49 C , the temperature of the upper
part.
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27. Results discussion
Stress/Strain due to convection and sun-light:
– from the simulation we can see that with steel we
have lower displacement and higher stress near
the constraint points because of the E modulus is
much higher than the poly one.
But just think to a 2.5mm steel dashboard
without the flexibility in shape of the
polypropylene?? It’s a crazy thing.
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