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MKIR Frame Finite Element Analysis. Model, Results, and Recommendations. Corner Support Brackets. ISS Attachment Brackets. Main Frame to Extension Frame Angle Brackets. Main Frame. Extension Frame. Main Frame to E-Box Angle Brackets. Main Frame Gussets.
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MKIR Frame Finite Element Analysis Model, Results, and Recommendations
Corner Support Brackets ISS Attachment Brackets Main Frame to Extension Frame Angle Brackets Main Frame Extension Frame Main Frame to E-Box Angle Brackets Main Frame Gussets Extension Frame to E-Box Angle Brackets Corner Support Plates Overall Model Description(E-Boxes Not Shown)
Modeling Assumptions • E-Boxes modeled as empty boxes with density modified to give correct weight • All angle bracket bolts modeled using a four bolt pattern • Recommended design change • Connections: • Angle and corner bracket connections are bolted • Extension and main frame tubing is welded • Main frame gussets are bolted to main frame • Attachment brackets are welded to the main frame • Corner support plates are welded to the main frame • Main frame to extension brackets rearranged to improve stress margins
Model Setup • Model Stats • 66,401 Nodes and 67,356 Elements • Entire model except bolts are linear quad thin shell elements • Bolts are linear DOF springs • Boundary Conditions • Clamped on corners of attachment bracket’s top face (Light Blue at left) • Loads • 1 G Applied in each orthogonal direction
Linear Static Stress Results(Main Frame) • 7177 psi max von mises stress occurs in Y load case
Linear Static Stress Results(Extension Frame) • 5082 psi max von mises stress occurs in Y load case
Results Discussion • All Margins are Positive G • Greater than 4 for frame structure • Greater than 2 for fasteners • Could be higher if bigger/better fasteners used • Using aluminum would triple the deflections, but would give the same stresses • More difficult to weld • Heat treatment probably necessary • Only provides weight savings, not increase in stress margins
Recommendations • Use four bolt pattern on each angle bracket face instead of two bolt pattern • Better handles moments on the brackets • Consider different positions for extension frame angles • Use configuration similar to the assumed location connecting main frame to e-box • More effective support for different load cases