FEA Lifting Device Det Sup

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National Institute for Nuclear Physics and High Energy Physics

Kruislaan 4091098 SJ Amsterdam

The Netherlands

NIKHEF Reference no.: MT-VELO 04-2

EDMS no: 466608

STRUCTURAL ANALYSIS OF THE

LIFTING DEVICEDETECTOR SUPPORTSFOR THE LHCb VERTEX LOCATOR (VELO)

M. J. Kraan, C. Snippe, J. Buskop, M. Doets

Abstract

The structural verification of the 'LHCb VELO detector support' lifting device is the

subject of this document. Purpose of these calculations is to investigate stress and

stability of this lifting device. This lifting device has to comply with the D1 CERN

Code. Numerical analysis was performed with the IDEASTM finite element analysis

software

April 2004


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STRUCTURAL ANALYSIS VELO DETECTOR SUPPORTLIFTING DEVICE2

Table of Contents

1. Introduction................................................................................................................3

2. General description of the Lifting Device .................................................................4

2.1 Design ..................................................................................................................4

2.2 Material properties ...............................................................................................5

2.3 Operational conditions.........................................................................................5

3. Finite Element Analysis .............................................................................................6

3.1 Lifting plate..........................................................................................................6

3.2 Cross plate............................................................................................................6

4. FEA results ................................................................................................................8

4.1 Lifting plate..........................................................................................................8

4.2 Cross plate..........................................................................................................10

5. Calculation bolt and sliding axle .............................................................................12

5.1 Sliding Axle .......................................................................................................12

5.2 Bolt M6 ..............................................................................................................12

6. Conclusion ...............................................................................................................13

APPENDICESA .. All Technical Drawings

B .. More FEA results


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1. Introduction

LHCb is one of the four particle physics experiments around the LHC

accelerator, which is located at CERN. The LHCb VErtex LOcator (VELO), shown in

figure 1.1, is one of the sub detectors of the LHCb experiment

Fig 1.1: VELO detector.

For installation of the two detector supports a lifting device has been designed.

Figure 1.2 shows the lifting device (in yellow) with the two detector supports in front

of the vacuum vessel. The scope of this document is to investigate stress and stability

of this lifting device. This lifting device has to comply with the D1 CERN Code.

Fig 1.2: Lifting device for installation of the two detector supports.


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2. General description of the Lifting Device

2.1 Design

The two main plates of this lifting device (shown in fig. 2.1) , so called 'lifting

plates', are bolted together with 4 intermediate plates. Between these two lifting plates

are two cross plates hanging in capacious slots. On the cross plates are the detector

supports mounted. To get a reasonable weight (43 Kg) for handling of this lifting

device, all plates are cut with a triangular or circular pattern.

Fig 2.1: Lifting device


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2.2 Material pro pert ies

This Lifting device will be made from Steel 47 (1.8905):

Tensile strength Rm [MPa] Min. 580

Yield strength Rp 0.2% [MPa] Min. 430

Young's modulus E [GPa] Min. 210

Density [g/cm3] 7.85

Poissons ratio 0.30

2.3 Operat ional condit ion s

The load of the lifting device is determined by the weight of the two detectorsupports. The weight for each detector support is 1100 N. This weight and the center

of gravity is calculated in the 3D modeling software. There are 8 holes to put in a

lifting bar for adjusting the center of gravity.

A safety factor used in the simulation is 2.4.

With a weight (G) of each detector of 1100 N, the load at each lifting point is:

F1=510

1100[ ] 2.4 12241100

N =

F2=590

1100[ ] 2.4 1416

1100

N =

Fig 2.2: Center of gravity of a detector support.


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3. Finite Element Analysis

A finite element analysis has been done to verify that the stresses are below

the Yield strength, and within the limits defined by the CERN safety code for lifting

devices D1. The finite element analysis is done with the finite element analysismodule of IdeasTM.

3.1 Lift ing plate

To simulate the 'worse case scenario', the first support point (see fig 3.1) of the

'lifting plate' is used (largest distance to the cross plates) and the forces are in vertical

direction placed on the surface on which the 'cross plates' are. The model is build up

with 2D Thin Shell parabolic quadrilateral. A buckling analysis is presented as the

stresses in some 'relative thin' sections are compressive.

Fig 3.1: FEA model of the lifting plate.

3.2 Cross p late

Due to the symmetry of the cross plate, half of the 'cross plate' has been

simulated. Two angle directions of the force are analyzed: 0 (vertical) and 30 degrees.

This 30 degrees (shown in fig 3.2) is a worse case lifting scenario. Under normal

conditions this force will always be vertical. The model is build up with 3D Solid

parabolic tetrahedron elements.


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Fig 3.2: 30 degrees lifting angle.

Fig 3.3: FEA model of the cross plate

Mesh types: lifting plate: 2D Thin Shell parabolic quadrilateral

cross plate: 3D Solid parabolic tetrahedron

Safety Factor: 2.4

Load type: Load on surface

Weight 1 detector support: 1100 N

Load Amplitude: lifting plate: F1=1224 N / F2=1416 N

cross plate: F=1416 N

Type of Solution: Linear Statics

Units: Length [mm]; Force [N]; Stress/Pressure [Mpa]

Table 3.1; summery of FEA properties.


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Fig 4.3: Deflection results. Max. 20.4mm. Without safety factor 20.4/2.4=8.5mm

Fig 4.4: First buckling mode. Buckling factor = 8.9.

Strain energy error norm = 1.7%


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4.2 Cross p late

Fig 4.5: 0 degrees; Von Mises stress results. Max. 90.2 MPa.

Fig 4.6: 0 degrees; deflection results. Max. 0.25 mm.


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Fig 4.7: 30 degrees; Von Mises stress results. Max. 349 MPa.

Fig 4.8: 30 degrees; deflection results. Max 4.2 mm.

Strain energy error norm = 5.2%


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5. Calculation bolt and sliding axle

Fig 5.1 detail cross plate with the 2 bolts and sliding axle.

5.1 Sliding Ax le

Material AISI 304

Yield strength = 290 N/mm2

F = 1416 N ; a = 30 mm; d = 12mm

Bending: 2b 3 3

1416 30250 /

1232 32

b

b

M F aN mm

dW

= = = =

Shear: 22 2

141612.5 /

124 4

F Fmm

dA = = = =

2 2 2

t?t b 3 251 / mm= + =

5.2 Bo lt M6

Material AISI 304

Yield strength = 290 N/mm2

Force F is divided over 2 M6 bolts: F = 1416/2 = 708 N

d = 4.7 mm (M6)

Tension:

2

2 2

708

41 /4.74 4

t

F F

mmdA = = = =


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6. Conclusion

For both lifting parts counts from the stress analysis point of view that the simulation

shows an stress level (lifting plate: max. 377 MPa; cross plate max. 349 MPa) below

the Yield strength (430 MPa).

Deformations on both parts are not critical and can only be a point of discussion for

installation reason.

For what concerns stability of the lifting plate, the linear buckling analyses shows a

comfortable safety margin (buckling mode 1, buckling load factor = 8.9).

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FEA Lifting Device Det Sup

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