Finite Element Analysis (FEA)
Center Frame
NIKHEF
MT group 		DATE:
March, 2000 		Project ID:
LHC-B 		Document ID:
......
Subject:
Stress and displacement of Centerframe
Prepared by:
M.J. Kraan
Notes:
Checked by:
Mr. M. Doets

Reasons for FEA:

Reasons for developing a FEA model for the centerframe is:

  • To investigate the deformations and displacements.

    Abstract:

    The 2 detector support-frames (see load-picture) in which the silicon detectors halves
    are mounted are supported on the Centerframe. For installation reasons this frame
    is standing on 3 legs.
    We have investicate 5 different models to optimise the deflection.
    The goal is to have less then 100 micron deflection.

    Material data: 

    Material:		Aluminium/Stainless Steel
Young's modules:	70.000 MPa / 210.000 MPa
Poisons ratio:		0.33
Shear Modulus:		26.3E3 MPa / 78E3 MPa

    FEA data: 

    Mesh type: 		..

Load type:		Pressure on Surface
Load Amplitude: 	600N (total) ->>>>>>>>>>
Type of Solution:	Linear Statics
Units:			Length [mm] / Stress [Mpa]

    MODEL 1

    Geometry:
    Stress [Mpa]
    Deflection [mm]
    		 
    
The maximum deflection is 0.7mm

    MODEL 2

    Geometry:
    Stress [Mpa]
    Deflection [mm]
    		 
    To decrease the deflection an open rib is added to the frame  
The maximum deflection is 0.4mm

    MODEL 3

    Geometry:
    Stress [Mpa]
    Deflection [mm]
    		 
    To investigate deflection with a "strong" rib,
 a solid rib is calculated
The maximum deflection is 0.24mm

    MODEL 4

    Geometry:
    Stress [Mpa]
    Deflection [mm]
    		 
    To stiffening the frame, some open plates are added
 at the outside. 
The maximum deflection is 0.38mm

    MODEL 5

    Geometry:
    Stress [Mpa]
    Deflection [mm]

    Al

    Stst

    		 
    To decrease the torsion, a hollow box is added at the rear of 
the frame and the ribs are made more "solid".
Using Aluminium, the maximum deflection is 0.054mm
Using Stainless Steel, the maximum deflection is 0.018mm
    Conclusion: 
    Model 5 showes that standing on 3 legs, deflections less 
then 100 micron in the Centerframe is possible. 
Next step is to optimise weight.