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This presentation by Chris Matthews from the University of Minnesota explores the critical aspects of structural and vibrational stress analysis applied to satellite design. Emphasizing compliance with mission requirements, the analysis aims to isolate and modify weak areas using ANSYS Workbench. Detailed meshing techniques, loading conditions, and the importance of achieving a fundamental frequency over 100Hz are discussed. Challenges related to model complexity and simulation errors are addressed, alongside methods for enhancing structural integrity through design adjustments.
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Satellite StructureSubsystem Structural and Vibrational Stress AnalysisPresented By:Chris Matthews University of Minnesota PDR
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
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
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
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
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
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
Acceleration Load Results University of Minnesota PDR
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
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
QUESTIONS??? University of Minnesota PDR