# Presentation: 075144

## Structural Analysis

Jeff Bolognese
16 November 2001 

- Jeff Bolognese
- 16 November 2001

## NASTRAN Finite Element Model

- Secondary support spider

- Metering structure (composite tube truss)

- Primary mirror
- (90% lightweighted fused silica with
- Ti bipods)

- Optical bench (composite face sheet/Al
- Honeycomb core with stiffeners)

- Aft Optics Assembly (Honeycomb with
- Composite frame and Ti flexures)

- S/C Mount Bipods (Composite tubes)

## Modeling Details

- Truss and Secondary Support Spider
- M55J composite structure
- 2.5” diameter tubes (.25” thick)
- H-channel stiffening ring
- 3 tangent blade spider
- Trades done on 4 and 3 blade non-tan. Structure

- Primary Mirror and Mount
- 90% lightweighted Fused Silica for mirror
- 3 Titanium bipods

## Modeling Details (Cont.)

- Optical Bench and S/C Mount Bipods
- Bench M55J composite facesheets with Al honeycomb core and composite stiffeners (6” deep)
- Bench mounts metering structure, primary mirror and aft optics module
- S/C mount bipods 5” diameter composite tubes (.25” thick)

- Aft Optics Structure
- Composite/Al honeycomb face sheets
- Composite truss structure
- 3 Ti flexure blades
- Lumped mass representation of fold and tertiary mirrors and detector assembly

## Analyzed mass = 658 Kg
Primary Mode = 32 Hz
Materials
M55J Composite: E= 1.4e+7 psi, CTE= -1.8e-7 mm/mm/C
Titanium: E= 1.6e+7 psi, CTE= 8.8e-6 mm/mm/C
Fused Silica: E= 9.85e+6 psi, CTE= 5.0e-7 mm/mm/C
Major structures included:
Metering structure
Secondary spider and secondary
18 Kg mass for mechanism
Optical bench
Primary mirror and mount
Aft optics structure
Simplified mass representation for fold, tertiary and detector

- Primary Mode = 32 Hz
- Materials
- M55J Composite: E= 1.4e+7 psi, CTE= -1.8e-7 mm/mm/C
- Titanium: E= 1.6e+7 psi, CTE= 8.8e-6 mm/mm/C
- Fused Silica: E= 9.85e+6 psi, CTE= 5.0e-7 mm/mm/C
- Major structures included:
- Metering structure
- Secondary spider and secondary
- 18 Kg mass for mechanism
- Optical bench
- Primary mirror and mount
- Aft optics structure
- Simplified mass representation for fold, tertiary and detector

- FEM Summary

## FEM does not include:
Baffles
Thermal masses
Solar arrays
Chopper mechanism
Full detector assembly mass
Spacecraft interface deck
Electronics boxes/harnessing

- Baffles
- Thermal masses
- Solar arrays
- Chopper mechanism
- Full detector assembly mass
- Spacecraft interface deck
- Electronics boxes/harnessing

- FEM Summary (Cont.)

## Analysis Summary 

- Analysis Summary

**Mode 1 = 32.4 Hz**

**Mode 2 = 34.4 Hz**

## Analysis Summary (thermal distortion)

- 1c X grad

- 1c Y grad

- 1c Z grad

## Update structural masses
Rerun quasi-static stress and dynamics analyses
Detailed model of detector assembly
Initial optimization analyses done on detector mount plate show lightweighting is feasible.
Model S/C interface deck
Additional updates for detailed structural/thermal/optical analysis
Detail optics and mounts
Apply on-orbit thermal loads
Further optimization of aft optics module and flexure blades and other structures where practical.

- Rerun quasi-static stress and dynamics analyses
- Detailed model of detector assembly
- Initial optimization analyses done on detector mount plate show lightweighting is feasible.
- Model S/C interface deck
- Additional updates for detailed structural/thermal/optical analysis
- Detail optics and mounts
- Apply on-orbit thermal loads
- Further optimization of aft optics module and flexure blades and other structures where practical.

- Future Analytical Work