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Analysis Overview

Satellite Structure Subsystem Structural and Vibrational Stress Analysis Presented By: Chris Matthews. Analysis Overview. Structural and Vibrational stress analysis proves design meets mission critical requirements Isolate, possibly alter weak areas of satellite design

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Analysis Overview

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  1. Satellite StructureSubsystem Structural and Vibrational Stress AnalysisPresented By:Chris Matthews University of Minnesota PDR

  2. Analysis Overview • Structural and Vibrational stress analysis proves design meets mission critical requirements • Isolate, possibly alter weak areas of satellite design • Analysis performed using ANSYS Workbench 11.0 at Minnesota Supercomputing Institute • ProE geometric assembly converted to .iges files and imported into ANSYS • Given Help and Suggestions for meshing and analysis from a contact at Honeywell University of Minnesota PDR

  3. Analysis Priorities • Stiffness of the structure critical requirement • >100Hz 1st Fundamental Frequency is hard requirement • Limit Acceleration Load Factors • AFRL decision makes loading omnidirectonal • 20g loading results should satisfy 2.0 (yielding) safety factor if stiffness requirement is met • Random Vibration and Acoustic Noise • Sine sweep and burst tests give idea for performance during AFRL random vibration test University of Minnesota PDR

  4. Simplification of Model for Analysis • Done with consulting from an engineer at Honeywell • Satellite solid model too detailed to mesh • Limited processing power and time • Model heavy internal components as “bricks” or simple masses • Suppress components that don’t affect the structural integrity • Solar panels, mounting plates, and spacers • Screw threading and indentations • Payload (electronics, sensors, computers) University of Minnesota PDR

  5. Meshing Conditions • ANSYS auto-generates mesh based on input of element sizes • ANSYS picks element geometry type: octahedral (cube) or tetrahedral (pyramid) • Specify different element sizes based on complexity of certain aspects of the design • Satellite panels: 0.4 cm • Torque Coils and Mounts: 2.0 cm • Component and Battery Box Bottoms: 0.5 cm • Component and Battery Box Lids: 2.0 cm • Component and Battery Box Sides: 2.0 cm University of Minnesota PDR

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  7. Boundary Conditions • Fixed Support: Lightband ring • Bottom Surface (ring) of Satellite doesn’t move • Interior surface of screw holes in ring also fixed University of Minnesota PDR

  8. Loading Conditions • Static Structural Conditions • 20g acceleration loading along principal axes • Applied as a body force at the center of gravity • Modal Analysis Conditions • Vibrate structure at all frequencies between 0 and 1000 Hz • Determines first 3 fundamental frequencies • Harmonic Analysis Conditions • Vibrate the structure at 100Hz and at fundamental frequencies • Look at stress and deflections caused by vibrations Z X Y University of Minnesota PDR

  9. Acceleration Load Results University of Minnesota PDR

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  21. Modal Analysis (Current Work) • Issues with getting the modal analysis to solve • Simulation restarts itself (sign of error) • Tried restricting the analysis • Restricting the range of frequency ANSYS sweeps • Lowering the number of fundamental frequencies ANSYS tries to solve for • Altering the conditions of contact surfaces • We know from z-direction 20g loading that top panel will have largest deflection • Stiffen top panel by thickening isogrid bars from 0.4 to 0.6 centimeters University of Minnesota PDR

  22. Current Work Work (Cont.) • Altering the top panel and running the simulations again under same conditions • Refining the mesh and solving again • Change element sizes for finer mesh • Results should converge to accurate values • Harmonic Analysis • More detailed solution of deflections and stresses caused by a certain frequency or multiple vibration frequencies applied to the structure University of Minnesota PDR

  23. QUESTIONS??? University of Minnesota PDR

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