1. Steven (“CJ”) Hiu 02/20/2008 Congratulations MAT Coders
Steven (“CJ”) Hiu 02/20/2008 Congratulations MAT Coders! Structural Analysis: Tanks and Intertank Couplers MAT Coder – Structures Acknowledgements: John Tsohas, Prof. Stephen Heister
AAE 450 Spring 2008

2. Structures Status Report
Good work done so far
Current Problems
High Inert Mass Fractions
Foreseeable problems moving into Phase II Design
Added loads on structure (Aero, Thermal, D&C, Avionics)
Added mass (Stringers, Baffles, Rings, Couplers, Pipes, Valves, Avionics)
Detailed analysis (Welding, Fasteners, Stress Concentrations)
3S mission success and 90% confidence against catastrophic failure
Ways Forwards
Safeguards in Preliminary Design (RF, conservatism)
Clever Design (spun hemicylinders etc) & Analysis (eg Pressure)
AAE 450 Spring 2008
Structures

3. Weight Saving – Pressurized Monocoque
Bruhn C8
Design curves based on test data
90% confidence curves
15-20% increase in tank strength vs axial buckling
(17% in MAT run)
30-40% increase in tank strength vs. bending (potential)
Potential weight savings
Flight pressure-stabilized design
AAE 450 Spring 2008
Structures

4. References
Bruhn, E, Analysis and Design of Flight Vehicle Structures, 1973
Huzel & Huang, Design of liquid propellant rocket engines, NASA SP-125, 2nd Ed.
Megyesy, E, Pressure Vessel Handbook, 10th Ed.
Acknowledgements
John Tsohas
Alan Schwing and Danielle Yaple for Matlab debugging
AAE 450 Spring 2008
Structures

5. Backup Slide 1 Increase in Axial Buckling Strength Source: Bruhn
Regression Plot of Increase in Compressive Buckling Stress due to Pressure
Source: Bruhn C8.11
Source: Bruhn
AAE 450 Spring 2008
Structures

6. Backup Slide 2 Buckling Strength Bruhn C8.2 Baker Method 3
Unconservative
No length effects
Baker Method 3
used in tanks Matlab code
AAE 450 Spring 2008
Structures

7. Backup Slide 3 Bending Strength of Cylindrical Tank
Source: Bruhn Fig C8.13a
AAE 450 Spring 2008
AAE 450 Spring 2008
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Structures

8. Backup Slide 4 Bending Strength with Internal Pressure
Source: Bruhn Fig C8.14
AAE 450 Spring 2008
Structures

9. Backup Slide 5
Bruhn A20
Stiffener-strengthened structures in shear and bending
Complicated analysis
Heavy
Expensive to manufacture
May be necessary
Matlab code 40% complete
Source: Bruhn Fig C8.14
AAE 450 Spring 2008

10. Backup Slide 6 Weld Efficiencies Weld is stronger than material
Knockdown effect at joins
Radiographic Inspection impractical?
Need to design stronger part to compensate
Source: Megyesevy
AAE 450 Spring 2008