***** PDF document file *****
TIS/GS-MS Safety Study Report
NIKHEF
MT group 		DATE:
april 2003		 Project ID:
LHCb		 NIKHEF No:
MT-VELO 03-01
Subject:
Stress analysis Lifting Point VELO STAND
Prepared by:
M.J. Kraan
 CERN EDMS No:
382302
Notes:
Checked by:
M. Doets
 CERN Document No:
LHCB-V-RPT-00001

Intoduction

The VELO will be installed as a pre-assembly in cavern UX85 at point 8.
The total mass of the detector, including the stand, is approximately 2,600 kg.
On the top corners of the stand are 4 removable lifting points which allow us
to lift the complete detector into position.
The stand and the lifting rods are made out of AISI 304 stainless steel.
These lifting points have to comply with the CERN SAFETY CODE [EDMS 335726].

Geometry data:

Material data: 

    Material:		AISI 304
Young's modules:	210 [GPa] 
Poisons ratio:		0.33
Yield Strength:         180 [MPa] 
Ultimate Strength:      460 [MPa]
Density:  		7.85 [g/cm3]

FEA data: 


    Mesh type(s): 		3D Solid parabolic tetrahedron

Savety constrains:      load lifted by only two points (4 points available)
			Safety factor = 2.4

Load(s):        	Weight 2 Detectors    =  4000 [N]
	 		Weight Vacuum Vessel  = 10000 [N]
			Weight Stand          =  6000 [N]
			Weight mechanics      =  6000 [N]   +
			                   ------------------
			Total weight VELO     = 26000 [N]
			
		      	Flifting = (26000/2)/cos19 * 2.4 = 33000 N

			F1=Flifting= 33000 [N]
			F2= reaction force from the lifting rod1)

			Moment of inertia:  I = phi * d4 / 64 = 306,796 mm4
			Deflection:  f = 6.2 - 4 = 2.2 mm 

			F2 = ( 3 * E * I *  f ) / l3 = 1742 N

			
Type of Solution:	Linear Statics
Units:			Length [mm]; Force [N]; Stress/Pressure [Mpa]

RESULTS:

stress
stress detail
displacement
displacement detail 

SUMMERY:
 max Stress (Von Mises) = 172 MPa
 max displacement       = 0.38 mm
CONCLUSION:

Max Stress of 172 MPa2) is below the yield strength (180 MPa), so still elastic.
A max displacement of 0.38 mm is no problem.

NOTES:
    1) Because of the safety constrains, this lifting rod will be deflecting (=6.2mm) more than the free
    space (=4 mm) in between, so this will cause the force [F2] on the tube

    2) Note that for the load, the safety factors are taken into account