Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

Nonlinear Buckling Analysison Welded Airbus

Fuselage Panels

P. ReimersIWiS GmbH

A. GorbaAirbus Deutschland GmbH

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

Contents

OverviewFE - ModelAnalysis ResultsComparison to Test ResultsConclusionDiscussion

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

Welded Panel Application

Airbus A318worldwide first application in large scaleserial productionfront and rearfuselage sections

Airbus A380under designother Airbus types

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

A318 rear fuselage welded panel location

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

Airbus panel test facility at AI-G

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

panel loading

FCo - compression loadFShv1,2 - vertical shear loadFShh - horizontal shear load

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

typical buckling shapes

100% shear 100% compression

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

load combinations

compressionload

shearload

0,0% 100,0%

41,6% 77,6%

79,7% 47,7%

87,3% 34,8%

94,9% 25,3%

100,0% 0,0%

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

FE panel model, mesh

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

FE panel model, detail

frame

clip

stringer

skin

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

criteria of failure load assessment

global:collapse of structureload decreases while deformations increase

local:material yieldslocal damage growth causes global collapse

– rivet failure– plastic zones (e.g. at top of skin buckles)– crack growth (e.g. in welds)

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

weld failure

weld opening stresses

procedure– locate εzz, max in stringer weld– calculate weld opening stress σw

– interpolate global load forσw = Rm, Stringer

at εzz, max location

σw = (σzz2 + τxz

2 + τyz2)1/2

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

100% compression load, buckling shape

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

100% compression load, compression stress

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

100% compression load, v. Mises stresses

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

100% compression load, weld stresses

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

100% compression load, weld stresses, detail

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

100% shear load,buckling shape and deformation

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

100% shear load, compression stress

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

100% shear load, shear stress

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

100% shear load, v. Mises stresses

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

100% shear load, weld stress

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

combined load, buckling shape and deformations

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

combined load, compression stresses

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

combined load, v. Mises stresses

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

combined load, weld stresses

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

combined load, weld stresses, detail

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

combined load, load vs. displacement

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

comparison of results

shear / compression interaction curvebased on panel failure load

0,0%

20,0%

40,0%

60,0%

80,0%

100,0%

0,0% 20,0% 40,0% 60,0% 80,0% 100,0%

compression load

shea

r lo

ad

Test ResultsAnalyses Results

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

FEA characteristics

ADINA FE-code used

124.000 DOF24.000 nodes8.700 elements

8-node shell elements for skin, stringer and frame3 x 3 Gaussian integration order in-plane3 Newton-Cotes integration scheme through thickness

1st mode shape of linear buckling analysis used as geometric imperfectionnonlinear static buckling analysis with automatic load-displacement ruled step incrementationlarge displacements and elastic-plastic material behaviour included

3 - 5 h CPU-time on 1,5 GHz Linux computer

Nonlinear Buckling Analysis on Welded Airbus Fuselage Panels FENet Conf. 4./5.12.2003

Conclusion

Fuselage panel tests are valuable in order to optimise the structural design.They are necessary as part of the approving procedure for licensing authorities.

FE analysis of test panels provide a more detailed look into the panel behaviour thandisplacement and strain gauges of limited number can offer.FE analysis serve to minimise test costs by replacing some test load combinations.

Good analyst experience is necessary in the subject of nonlinear FE analysisconduction and in modelling the specific boundary conditions of the panel test rig.