Vertical-flexure CCD module: Thermal and Dynamic FEA
description
Transcript of Vertical-flexure CCD module: Thermal and Dynamic FEA
Vertical-flexure CCD module:Vertical-flexure CCD module:Thermal and Dynamic FEAThermal and Dynamic FEA
Bruce C. Bigelow
University of Michigan
Department of Physics
10/28/04
2
Vertical-flexure CCD moduleVertical-flexure CCD module
Objectives: Accommodate Moly-Invar CTE mismatch with vertical
flexure Moly CCD mount (see previous presentation) Demonstrate acceptable thermal stresses for package over
survival temperature range Demonstrate acceptable modal performance for package
3
CCD module FEACCD module FEA
4
CCD module FEACCD module FEA
5
CCD module FEACCD module FEA
6
Vertical-flexure module FEAVertical-flexure module FEA
Analyses: Neglect AlN, silicon from models (TZM and Invar only) No pre-stress of package at room temp TZM Flexure geometry (not optimized):
Blade thickness = 0.4 mm (0.016”) Blade width = 8 mm (0.32”) Blade effective length = 4 mm (0.16”)
Thermal: Simple delta-T = -160K, constant CTEs Frame constrained for zero mounting stress
Dynamic: Mounting pads constrained TZM Flexure to Invar joint nodes coupled
7
CCD module FEA - elementsCCD module FEA - elements
8
Vertical-flexure module FEAVertical-flexure module FEA
Analyses: Thermal:
Simple DT = -160K, constant CTEs Frame constrained for zero base stress at mounting Flexures and Invar base interface nodal deflections
coupled at centerline to simulate single screw constraints (very conservative – neglects screw head constraint)
Z constraints coupled at top of Invar surface (worst case)
9
CCD module FEA – node couplesCCD module FEA – node couples
10
CCD module FEA – frame stressCCD module FEA – frame stress
Max stress in flexures – 132 MPa – 19,410 PSI (TZM Sy = 860 MPa)
11
CCD module FEA – Invar stressCCD module FEA – Invar stress
Max stress in Invar – 5.6 MPa – 812 PSI (Invar Sy = 300 MPa)
12
CCD module FEA - elementsCCD module FEA - elements
Max distortion of Invar base (CCD mounting surface) is 0.1 micron
13
Vertical-flexure module FEAVertical-flexure module FEA
Analyses: Dynamic:
Modal analysis, reduced (Householder) modal extraction TZM - Invar interface nodal deflections coupled as in thermal case First 10 frequencies:
» SET TIME/FREQ
» 1 3279.8
» 2 3458.6
» 3 3955.8
» 4 5009.2
» 5 6928.7
» 6 7684.2
» 7 8830.7
» 8 9707.0
» 9 12753.
» 10 13239.
14
CCD module FEA - DynamicCCD module FEA - Dynamic
15
CCD module FEA - DynamicCCD module FEA - Dynamic
16
CCD module FEA - DynamicCCD module FEA - Dynamic
17
Vertical flexure CCD moduleVertical flexure CCD module
Conclusions: Thermal and dynamic FEA presented Low thermal stresses demonstrated with non-optimized TZM
flexures High resonant frequencies demonstrated with non-optimized
TZM flexures Optimal flexure dimensions still TBD for minimal stress and
maximum first resonance