NIKHEF
MT group 		DATE:
november 2002		 Project ID:
LHC-B		 Document ID:
......
Subject:
Stress and displacement Secundary Vacuum Foil
Prepared by:
M.J. Kraan
Notes:
Checked by:
.....

Reasons for FEA:

Investigate the displacements in the Secondary Foil
occur by a difference-pressure between the secundair- and primair vacuum.

Geometry data:

Material data: 

Material:		AlMg3
Young's modules:	70.000 MPa
Poisons ratio:		0.33
Shear Modulus:		27.3E3 MPa
Yield Strength:         80 MPa (annealed)
Ultimate Strength:      180 MPa (annealed)

FEA data: 

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

CALCULATION 1: TOBLERONE TOP FOIL 10 mBar pressure difference

    The thickness of the foil is not constant,
    due to the plastic deformation during forming.
    See picture for used shell thickness at some regions.
    Starting thickness = 0.3mm

    Primary Pressure > Seconday Pressure
    Max deflection
    0.88 mm

    Secondary Pressure > Primary Pressure
    Max deflection
    1.04 mm

    >> Go to deflection test results

CALCULATION 2: Secondary Vacuum Foil - 2 mBar pressure difference

    The thickness of the foil is not constant,
    due to the plastic deformation during forming.
    See picture for used shell thickness at some regions.
    Starting thickness = 0.3mm

    Primary Pressure > Secondary Pressure
    Magnitude
    X direction
    Z direction
    Max deflection in topfoil = 0.458 mm

    Secondary Pressure > Primary Pressure
    Magnitude
    X direction
    Z direction
    Max deflection in topfoil = 0.439 mm

CALCULATION 3: Secondary Vacuum Foil - 25 degrees temperature difference

    temperature imput
    deflection
    Max deflection = 0.22 mm