Finite Element Analysis (FEA)
Exit Foil
NIKHEF
MT group 		DATE:
januari 03, 2000 		Project ID:
LHC-B 		Document ID:
......
Subject:
Stress and displacement of vacuum chamber end-foil
Prepared by:
M.J. Kraan
Notes:
Checked by:
Mr. M. Doets

Reasons for FEA:

Reasons for developing a FEA model for the endfoil are:

  • To investigate the stress and strain that occur in the endfoil for different endfoil-shapes.
  • 2 To study and predict deformations and displacements.

    Abstract:

    We have calculate 3 different exit foil shapes: Model 1 to 3.
    In this calculations the endfoil is made of aluminium, with a thickness of 2 [mm].
    The flanges are represented as boundary conditions.
    We have studied 2 different cases:

  • Connection to the Vacuum Chamber (beampipe) FREE, to simulate a ideal bellow connection
    between Exitfoil and Vacuum Chamber.
  • Connection to the Vacuum Chamber (beampipe) FIXED, to see how stresses will be in the Exitfoil
    and the Vacuum Chamber when there is no bellow connection

    Material data: 

    Material:		Aluminium
Young's modules:	70.000 MPa
Poisons ratio:		0.29
Shear Modulus:		26.3E3 MPa

    FEA data: 

    Mesh type: 		Thin Shell parabolic quadrilateral
Shell Tickness: 	2 mm
Load type:		Pressure on Surface
Load Amplitude: 	0.1 Mpa
Type of Solution:	Linear Statics
Units:			Length [mm] / Stress [Mpa]

    MODEL 1

    Geometry:
    FREE:
    FIXED:
    postscriptfile
    FREE: Maximum stress of 498 MPa at the Flange connection
      Maximum displacement of 5.6 mm at the Vacuum Chamber connection
FIXED:Maximum stress of 106 MPa at the Vacuum Chamber connection
      Maximum displacement of 0.8 mm in the Exitfoil

    MODEL 2

    Geometry:
    FREE:
    FIXED:
    postscriptfile
    FREE: Maximum stress of 331 MPa in the Exitfoil
      Maximum displacement of 12.5 mm at the Vacuum Chamber connection
FIXED:Maximum stress of 36.3 MPa at the Vacuum Chamber connection
      Maximum displacement of 0.12 mm in the Exitfoil

    MODEL 3

    Geometry:
    FREE:
    FIXED:
    postscriptfile
    FREE: Maximum stress of 42.8 MPa in the Exitfoil
      Maximum displacement of 0.33 mm at the Vacuum Chamber connection
FIXED:Maximum stress of 37.8 MPa at the Flange connection
      Maximum displacement of 0.163 mm in the Exitfoil

    Conclusion:
    It is recommended to use a bellow in the Vacuum Chamber connection to the Exit Foil,
    this to avoid unknown stresses. Comparing stresses in the 3 models, the most
    favorable one is model 3 with the Free (bellow) connection to the Vacuum Chamber (Beampipe).