Design Analysis of a Minimum Weight Wingae462/AE462_ProjectPresentation_Dababneh_… · Skin 1Skin 2Skin 3 Spar Web 1 Spar Web 2Rib 1Rib 2 ROOT 1.6 1.6 2.03 1.6 1.6 1.2 1.6 TIP 0.63

T P j tTerm Project

Design & Analysis of a Minimum Weight Wing

AE 462 Aerospace Structures DesignAE 462 Aerospace Structures DesignDepartment of Aerospace Engineering, METU

Odeh Dababneh, 132180‐1Coşkun ÖZAŞÇILAR 102876‐0Coşkun ÖZAŞÇILAR, 102876 0

18 June 2009

Project Definition

The properties of the designp p g

Half wing structure for a single engine utility aircraft

Straight and unswept wing = RectangularStraight and unswept wing = Rectangular

NACA 2412 Wing

Chord : 1.524 m (5 ft)

Semi span: 4.572 m (15 ft)

Aircraft Maximum Takeoff Weight: 1460 kg

Aircraft Minimum Operating Weight: 861 kg

Dive Speed: 270 mile per hour

Department of Aerosace EngineeringMiddle East Technical Universityby Odeh Dababneh & Coşkun Özaşçılar

19.06.2009AE 462 Term Project: Design & Analysis of a Minimum Weight Wing

Page 2

Design Requirements

Minimum weight designMinimum weight design

FAR Part 23 Appendix AFAR Part 23 Appendix A

f b l & d dManufacturability & standard size

Factor of Safety = 1.5

Divergence Speed > Dive Speed



Page 3

Loading @ A

3000035000

Spanwise Shear Force Distribution

50001000015000200002500030000

Spanwise Bending Moment Distribution0

5000

0 0.2 0.4 0.6 0.8 1 1.2Unit Span (m)

40000500006000070000

Spanwise Bending Moment Distribution

Spanwise Pitching Moment Distribution(N.m)0

100002000030000

0 0 2 0 4 0 6 0 8 1 1 2

-800-600-400-200

00 0.2 0.4 0.6 0.8 1 1.2

p g ( ) 0 0.2 0.4 0.6 0.8 1 1.2Unit Span (m)

-1600-1400-1200-1000

Unit Span (m)



Page 4

Loading @ D

250003000035000

Spanwise Shear Flow Distribution

500010000150002000025000

VZ (N

)

6000070000

Spanwise Bending Moment Distribution

00.000 0.200 0.400 0.600 0.800 1.000 1.200

Unit Span (m)

2000030000400005000060000

S i Pit hi M t

01000020000

0.000 0.200 0.400 0.600 0.800 1.000 1.200Unit Span (m)

-2000

-1000

00.000 0.200 0.400 0.600 0.800 1.000 1.200

Spanwise Pitching Moment

-5000

-4000

-3000

Unit Span (m)



Page 5

Unit Span (m)

Selection of Analysis Tool

Analysis tool = MATLAB 2006aAnalysis tool = MATLAB 2006a

The tool must be well known by all the project partners.

The tool must be capable of mathematical operations.

The tool must be capable of programming through an algorithm.p p g g g g

The tool must be capable of presenting charts and graphs.



Page 6

The Flowchart ‐ I

STARTB

Input: General wing geometry, flight parameters, factor of safety

C l l t E t l L d (ESDU)

Calculate: Inertial and geometrical parameters

Calculate: External Load (ESDU)

Calculate: Internal Load

Calculate: Axial stress and Shear FlowsRe‐Sizing

Check: Axial

C

Initial sizing (geometry and material)

Check: Axial Strength and Shear Stress

FAILED

Calculate: Critical buckling stressesFAILED

Assume: Shear center = aerodynamic center

FAILEDA

Check: Buckling Condition

OKA Condition



Page 7

The Flowchart ‐ II

A

Calculate: Margin of Safety (MoS)Calculate: Divergence speed

Calculate: Margin of Safety (MoS)

Check: Minimum positive

MoS

>> 0+

Comparing weights for points A & D, decide the most critical divergence

speed: at A or D?:

≈ 0+

Calculate: Shear Center @ each section

FINISHB

Check:Shear Center Location

Δ > 1%

Carry the loads to shear centers

Calculate: Minimum Weight

Δ < 1%

CCalculate: Sectional GJ and S/C‐A/C

distance at 75% wing span



Page 8

Selection of Material

Aluminum 2024‐T3

• High strength Aluminum and excellent fatigue resistance.

• Advantage on structures and parts where good strength‐to‐weight ratio is desired.

MATERIAL PROPERTIES

Ulti t T il St th 483 MPUltimate Tensile Strength 483 MPa

Tensile Yield Strength 345 MPa

Modulus of Elasticity 73,1 GPay

Shear Modulus 28 GPa

Shear Strength 283 MPa

Density 2780 kg/m3



Page 9

Spar Caps and Stiffners: Location & Areas

X3X2

X1

X4

Unsymmetric Bending Formula Best Location for Minimum Spar & Stiffner Area

12 % ≤ X1 ≤ 20 % of Chord X1 = 20

55 % ≤ X2 ≤ 70 % of Chord X2 = 55

X1 X2

X3 X4

X1 ≤ X3 ≤ X2 X3 = 32

X1 ≤ X4 ≤ X2 X4 = 31Iterate the locations, keep all else constant...



Page 10

Skin, Web & Rib Thicknesses

Skin 1Skin 2

Spar Web 1 Spar Web 2

Skin 3

Shear Flows Max Shear Stress Minimum Thickness Check Buckling Minimum Thickness

Skin Thicknesses

Web Thicknesses

All Thicknesses

For Buckling

Iterate the thicknesses, keep all else constant...

Rib thicknesses are determined here...



Page 11

Margin Of Safety

FLANGES

Root

Tip

WEB & SKINS

Root

Tip



Page 12

Shear Center

Manual iteration for the shear center location:

Shear Center = Aerodynamic Center = 25 % chord

Shear Center = 42 % chordRe‐calculate all

Assume

Shear Center 42 % chord

Shear Center = 44 % chord

Re calculate all

Re‐calculate all

Shear Center = 44 % chordRe‐calculate all



Page 13

Note on Weight Optimization

Component PercentageComponent Percentage

Skins 60%

Spar Caps & Stiffners 20 %

Spar Webs 10 %

Ribs 10 %

TOTAL 100 %

Weight reduction on SKINS is more effective



Page 14

Manufacturability & Standards

Aluminum 2024 T3

48" x 144" 0.012" 0.016" 0.020" 0.025" 0.032" 0.040" 0.050"

1219mm x 144mm 0.30mm 0.4mm 0.5mm 0.63mm 0.81mm 1.016mm 1.27mm

48" x 144" 0.063" 0.071" 0.080" 0.090" 0.100" 0.125" 0.160"

1219mm x 144mm 1.60mm 1.8mm 2.03mm 2.28mm 2.54mm 3.17mm 4.06mm

Al 2024 T3 Angles (L – Profile)

Dimensions (inch) Areas (mm^2)

1/2 X 1/2 X 1/16 38

5/8 X 5/8 X 1/16 48

3/4 X 3/4 X 1/16 58

7/8 X 7/8 X 1/8 131

1 X 1 X 1/16 78

1 X 1 X 1/8 151

1 X 1‐1/2 X 1/8 232

1‐1/2 X 1‐1/2X1/16 118

1‐1/2 X 1‐1/2X1/8 232

2 X 2 X 1/8 312



Page 15

3‐1/2 X 3‐1/2X1/4 1.089

Result: Cross Sections, Spacings & Thicknesses

AREAS (mm^2)

Spar Cap 1 Spar Cap 2 Spar Cap 3 Spar Cap 4 Stiffner 1 Stiffner 2

ROOT 520 360 315 375 520 400

TIP 38 38 38 38 38 38

ROOT TIP

Station 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Percent 0 3 6 9 13 17 22 27 34 41 48 55 65 85 100

Y (m) 0 0.046 0.091 0.137 0.198 0.259 0.335 0.411 0.518 0.624 0.731 0.838 0.991 1.295 1.524

THICKNESS(mm)

Skin 1 Skin 2 Skin 3 Spar Web 1 Spar Web 2 Rib 1 Rib 2

ROOT 1.6 1.6 2.03 1.6 1.6 1.2 1.6

TIP 0.63 0.81 0.81 0.63 0.63 0.3 0.3



Page 16

Result: Weight

C tA D

Componentkg % kg %

Skins 29.267 56.5 30.708 57.7

Spar Caps & Stiffners 10.998 21.2 11.023 20.7

Spar Webs 4.924 9.5 4.818 9.1

Ribs 6.595 12.8 6.656 12.5

TOTAL 51.784 100 53.205 100

Divergense Speed@ A

308 6 /

Divergense Speed@ D

322 8 /308.6 m/s 322.8 m/s



Page 17

Documents

Design Analysis of a Minimum Weight Wingae462/AE462_ProjectPresentation_Dababneh_… · Skin 1Skin 2Skin 3 Spar Web 1 Spar Web 2Rib 1Rib 2 ROOT 1.6 1.6 2.03 1.6 1.6 1.2 1.6 TIP 0.63