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Optimization Assisted Concept Design of Aircraft Floor Structures

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Optimization Assisted Concept Design of Aircraft Floor Structures

  1. 1. Optimization Assisted Concept Design ofAircraft Floor StructuresWolfgang Machunze09. November 2011
  2. 2. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Outline• Project scope• Concept idea• Using HyperWorks concept design phase of innovative PAX floor structure  Sub modelling technique  Free size optimization  Sizing of composite cross beam  Parameterisation of CAD models CATIA V5 - Hypermesh morphing  Shuffle optimization – Stacking rules• Manufacturing of sized cross beam structure• Pax floor design status• OutlookPage 2
  3. 3. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Project scopeScope: APax floor within typical fuselage area ofreference A/C NGA AConcept targets: Section cut A-A• Weight saving• Pax floor height reduction• Modularization – pre equipped structures• Low cost manufacturing Pax floorPax floor design driver:• Statics, dynamics• Attachment points (seat rails, z-strut)• System installationPage 3
  4. 4. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Concept ideaBasic concept idea:• CFRP cross beam concept with systems below cross beam  minimize PAX floor height and structure weight• Improve maintainability in flight and enable modularization during assembly of PAX floor• Use manufacturing approach braiding to realize cranked cross beam  systems within cranking area Reference - CFRP Concept idea - CFRP SystemsPage 4
  5. 5. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Sub modelling technique• Sizing of sub components within global aircraft FE-model with realistic surrounding loads, stiffness and boundary conditions• Reduction of simulation time by using superelement approach: surrounding structure (red) represented by KAAX & PAX matrix• Check of approach: Displacement for dimensioning load case of cross beam structure “Rapid Recompression” (typical fuselage section 16/18) Global FE ISSY model Sub model with KAAX & PAX Sub model for PAX floor sizing Surrounding aircraft structurePage 5
  6. 6. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Cross beam - dimensioning load cases Symmetrical landing• 8 load cases considered within sizing process for cross beam structureDesign mainly driven by bending loads• Ground Loads Turbulence lateral  Symmetrical landing case• Gust Loads  Continuous turbulences lateral• Failure Loads  Rapid decompression up Rapid decompression up Rapid decompression down  Rapid decompression down• Double inner pressure – tension loadsPage 6
  7. 7. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Free size optimization - Concept development• Using free size optimization for first concept weight comparison using homogeneous material  Stiffness constraint Course of  Minimum mass moments over cross beam• Detection of high loaded area using free size optimization and comparing with analytic course of moments and transverse forces• According to results modification of cross beam design Design processPage 7
  8. 8. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Sizing optimization• CFRP sizing optimization considering manufacturing constraints with target robust design• Span direction 4 varying areas with differing design variables – By equations forced to minimized thickness steps within cross beam to reduce manufacturing effort – Crossbeam:Page 8
  9. 9. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Sizing optimization - constraints Mid-point Z• Stiffness LC 574 LC 576 Y Max. deflection allowed [mm] + xx,xx mm - xx,xx mm• Stress ^ ^ – Max-Stress criteria: 1c  1  1t 1 IMA :• Strain  1    12  2 2  – Evaluated via 2 equations:       0.00 xx   0.00 xx  Modes Eigenvalue range• Stability 15 0.05 < λ < 3• Manufacturing constraints• Laminate stacking rules – Percentages to meet the rules in later shuffle optimizationPage 9
  10. 10. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Shape Optimization – Shear centre• Consideration of shear centre within optimization steps using design variables and equations Prevent crossbeam twist Force• PAX floor panel nodes from ISSY-model used for load introduction  node coordinates need to be modified by actual shear centre Shape• Steps for integration: 3t f b 2 1. Equation for shear centre:  SC   6bt f  h t w     h  2. Shape variable for node within realistic range 5 mm < Shape < 15 mm 3. Scaling of shear centre 4. DLINK2 to link shape DESVAR with scaled shear centrePage 10
  11. 11. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Shape optimization of cranking area Shape variable Minimum principal strain• Shape optimization within critical cranking area to reduce compression strain within flanges• Design variable: Shape• Objective: Max. Min. Principal StrainPage 11
  12. 12. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Shuffle optimization• Transfer of sizing results into stacking sequence considering stacking rules defined by Airbus• Easy tool to stack complex results in manufacturable order Super Ply level StackingPage 12
  13. 13. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Model variation by morphing• Morphing basing on parametric CATIA V5 models  mesh and connection elements (MPC, RBE2) can remain only map to geometry• Design study within first project steps possible Reference CCB-A Simple crank CCB-B Several crankConceptDeviation 100 % 103,8 % 111,3 %WeightPage 13
  14. 14. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Weight analysis – aircraft level• Weight analysis must be done on aircraft level  No inner false rail necessary  Minimal thicker floor panels  Slight weight increase for cross beam Weight/frame bay Reference NGA CCB Cross Beam [%] 100 104 Bracket (LT) [%] 100 300 (aluminium brackets radius) (aluminium brackets radius + bracket free side) Floor panel [%] 100 110 Inner false rails [%] 100 0 Total weight 100 102Page 15
  15. 15. Optimization assisted concept design of aircraft floor structures 14 November, 2011 PAX floor concept – current status• Next to structural design also system CCB – system architecture architecture important for PAX floor concept• Target: combine structural optimization with target of optimal system architecture CCB – no inner false rail necessaryPage 16
  16. 16. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Manufacturing of 4,5 m cross beam structure Braiding of 4,5 m cross beam Winding of 4,5 m cross beam Infiltration of 4,5 m cross beam on CFRP tool within ECD-Autoclave as VAP process UD-layer Very good quality of infiltrated cross beamPage 17
  17. 17. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Summary & Outlook Weight saving• Achievements for current project status: Pax floor height reduction Cost reduction System installation• Optistruct with its tools can be used for various tasks• Static testing of cross beam structure according to pressure load distribution of cross beam structure  validation of numeric results• Fuselage demonstrator with innovative PAX and Cargo concepts in 2012Page 18
  18. 18. Optimization assisted concept design of aircraft floor structures 14 November, 2011 Thank you for you attention!Wolfgang MachunzeWolfgang.Machunze@eads.net+49 (0) 89-607 29580 Page 19

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