6. 2. CONSTRAINTS
IFAE - MECHANICAL DEPARTMENT 6
-20 ⁰C to +40 ⁰C
36 Km/h
60 Km/h
50 Km/h
83,5 Km/h
120 Km/h
200 Km/h
Max const.
Max gust
Observation Repositioning Safe state
Snow: 500 mm
Ice: 20 mm
ENVIRONMEN
T
Horitzontal: 0,49 g
Vertical: 0,6 g
2396 m
70 mm (1h)
200 mm (24h)
1200 W/m2
Roque de los Muchachos
(La Palma) Canary Islands
+30 ⁰C (24h)
7. 2. CONSTRAINTS
IFAE - MECHANICAL DEPARTMENT 7
OPERATIONA
L
Azimuth: 0,1⁰ Azimuth repos: <20 s
Local mode stop: <1 s
Azimuth: ±270 ⁰
Azimuth: -100 ˞47 mrad/s2
Azimuth: 8,4 ˞230 mrad/s
30 years
< 5 min
13. 3. DESIGN
IFAE - MECHANICAL DEPARTMENT 13
FRAME
Wheel tread on the rail
Model meshing
Hertz contact stress on the rail
wheel rail
FEA wheel/rail model
15. 3. DESIGN
IFAE - MECHANICAL DEPARTMENT 15
ANTIUPLIFT
FRAME
CFD calculations
showed that uplift
forces may appear
from 70 Km/h
Frame
brass bush
brass bush (x2)
wheel (x2)
(roller coaster
concept)
eccentric heigh adjuster
18. 3. DESIGN
IFAE - MECHANICAL DEPARTMENT 18
* Thermal expansion of lower
structure must not transmit
radial loads to bogies.
NODE JOINT
roller linear guides
(free radial movement)
* No torque should be
transmitted from bogies to CF
lower structure.
1 (linear guide)
spherical b
assembly
node joint
degrees of freedom
3 (sphere)
4 DOF
+
19. 3. DESIGN
IFAE - MECHANICAL DEPARTMENT 19
NODE JOINT
Simplified FEA model
(displacements scaled x10)
43. IFAE - MECHANICAL DEPARTMENT 43
6. TESTING
BENCH TEST
cylinder
Ø250 x Ø140
gantry structure
dummy node
44. IFAE - MECHANICAL DEPARTMENT 44
6. TESTING
RADIAL LOAD
linear guides sliding
resistance is very low
compression &
extensión load
radial movement
To apply a radial force on the node
(with vertical load).
Purpose of this test is to check the
sliding resistance of the linear guide.
45. IFAE - MECHANICAL DEPARTMENT 45
6. TESTING
MOTOR TORQUE
300 Nm
300 Nm
To apply max motor torque.
(no vertical load).
Purpose of this test is to check the
node reactions and displacements.
46. 300 Nm
300 Nm
IFAE - MECHANICAL DEPARTMENT 46
6.TESTING
COMPRESSION
To apply compression force on the node +
radial push/pull + motor torque.
Purpose of this test is:
-To check no permanent set occurs in the
bogie.
-To quantify BOGIE rolling resistance.
-To check linear guide performance under
load.
Compression: 825 kN
(equivalent to 200 Km/h wind)
47. 300 Nm
300 Nm
IFAE - MECHANICAL DEPARTMENT 47
6.TESTING
EXTENSION
To apply extension force on the node +
radial push/pull + motor torque.
Purpose of this test is:
-To check no permanent set occurs in the
bogie.
-To quantify BOGIE rolling resistance.
-To check linear guide performance under
load.
Extension: 544 kN
(equivalent to 200 Km/h wind)
48. IFAE - MECHANICAL DEPARTMENT 48
6. TESTING
DURABILITY TEST
To apply cyclic loads that simulates bogie lifetime.
Cycle pattern is defined according to wind statistics
of last 10 years at telescope site (ORM observatory).
Purpose of this test is to confirm that no cracks nor
permanent set occurs during the fatigue test.
49. IFAE - MECHANICAL DEPARTMENT 49
6. TESTING
DYNAMIC TEST
To accelerate/decelerate bogies.
Purpose of this test is:
- To check pinion-crown meshing performance
(vibration, noise…)
- To measure rolling resistance
- To measure energy consumption
50. THANK
YOU!
IFAE MECH DPT INVOLVED IN CTA LST
BOGIES:Ferran Grañena (left
2015)
Luís Lopez (left 2015)
Carles Arteche (left 2016)
Juli Mundet
Rafa García
Javier Gaweda
David Benedicto
