NIKHEF
MT group 		DATE:
december 2002		 Project ID:
LHC-B		 Document ID:
......
Subject:
Normal modes of the secondary vacuum foil
Prepared by:
M.J. Kraan
Notes:
Checked by:
M. Doets

Reasons for FEA:

To investigate the normal modes of the Detector Vacuum Foil.

Abstract:

Calculation of the first 10 normal modes of the aluminium Detector Vacuum Foil

Geometry:

Material data: 

Material:               Alumium
Young's modules:        70.000 MPa
Poisons ratio:          0.29
Mass density:		2700 Kg/m^3

FEA data: 

Mesh type: 		Thin Shell parabolic quadrilateral
Type of Solution:	Normal Mode dynamics - Lanczos
Units:			Length [mm] / Stress [Mpa]
    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
RESULTS:

MODE 1
FREQ: 107 Hz		 MODE 2
FREQ: 120 Hz		 MODE 3
FREQ: 128 Hz		 MODE 4
FREQ: 146 Hz		 MODE 5
FREQ: 164 Hz
MODE 6
FREQ: 177 Hz		 MODE 7
FREQ: 184 Hz		 MODE 8
FREQ: 193 Hz		 MODE 9
FREQ: 199 Hz		 MODE 10
FREQ: 208 Hz