director of institute avikon professor komarov v.a ...airframe design process. 4 ewade 2007 komarov...

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EWADE 2007 Komarov V.A.

Modern Trends in AirframeStructural Design

Professor Komarov V.A.Director of Institute AVIKON

Of Samara State Aerospace University

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EWADE 2007 Komarov V.A.

Plan of the presentation

1. General view on the modern structural design problems.

2. New ideas for improving design process.3. The example of using a new ideas for

research aerodynamic and weight efficiency of morphing wing.

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EWADE 2007 Komarov V.A.

Airframe design process

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EWADE 2007 Komarov V.A.

Time and resource expediture

The main reason of greater charges of time and resources in sequential design paradigme is use very simple, (insufficiently exact) mathematical models on early stage of design.

For reduction of designing time it is suitable use of highly accuracy mathematical modelson early stage design.

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EWADE 2007 Komarov V.A.

New paradigm for Airframe Structure Design

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EWADE 2007 Komarov V.A.

The problem of weight estimation in structural design

1. Choice of structure topology (skeleton design).2. Estimation of structural mass fraction.3. Weight estimation of the wing, fuselage, etc.4. Weight check.

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EWADE 2007 Komarov V.A.

Choice of structure topology

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EWADE 2007 Komarov V.A.

Estimation of structural mass fraction

Definition of flight vehicles takeoff gross weight via “equation of existence”

whereppfsysst

plo mmmm

mm

−−−−=

1

stst

o

mmm

=

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EWADE 2007 Komarov V.A.

Example of calculation a wing mass fraction via “weight equation”

Typical weight equation (Eger)

( ) 015,05,4311

14

cos10

7

0

32

5,175,000

4

01st ++

+−−∗

++∗=

pkk

cp

mnkm p

ηµ

ηη

χ

ϕλ

0 0,05 0,1

0,15 0,2

0,25

0,3 0,35 0,4 stm

mo = 270 000 kg mo = 685 000 kg

Mel

vill

Lipt

rote

Farre

n

Taye

Den

t

Koz

lovs

ky

Drig

gs

Bad

yagi

n

Ray

mer

Eger

Patte

rsso

n

Tore

nbee

k

Shej

nin

Aver

age

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EWADE 2007 Komarov V.A.

Weight Check

1. Definition of the weight limits for different part of structure before design.

2. Analyses of weight penalty after design (if necessary). Looking for decrease of structural mass.

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EWADE 2007 Komarov V.A.

Unconventional flight vehiclesMorphing Wing from TUDelft

?=stm ??=stm(http://www.lr.tudelft.nl/live/pagina.jsp?id=fd5540a7-0cfe-44e5-b1bc-c806fa0410b8&lang=en )

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EWADE 2007 Komarov V.A.

New ideas for improving design process

1st idea. Load-carrying factor

Frame

Thin-wall structure

3D-structure

∑=

⋅=n

iii lNG

1

∑=

⋅=n

iii SRG

1

∫=V

eqvdVG σ

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EWADE 2007 Komarov V.A.

Definition of structural mass via“load-carrying factor”

Theoretical structural material volume

Real mass of structure

or

G – take into account topology, geometry and external loads– specific durability of material– coefficient of full-mass structure, (it depends on design and technology perfect)

G-criteria allows to calculate absolutely mass of unconventional structure with high accuracy

[ ] i

n

iii

n

i

iT lFlV ⋅=⋅= ∑∑

== 11

Nσ

[ ]σρϕρϕ GVm Tst ⋅⋅=⋅⋅=

σϕ Gmst =

σϕ

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EWADE 2007 Komarov V.A.

2nd idea. Size less criteria of load carrying perfection of structure

Load-carrying factor is proportional to the linearsizes (coordinates of nodals) of structure andvalue of nodal forces (at retaining of the law ofdistribution of external loading) –dimensional quantity

Sizeless criteria– coefficient of load carrying factor

where P- specific loadL- specific size

whence (aerodynamic analogy : )

LPGCK ⋅

=

PLCG K= qSCY y=

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EWADE 2007 Komarov V.A.

Example of simple structures

CK = 2,00

α

l

a

c

b

d

aP

l

CK = 3,41aP

b

d

a

c

h

CK = 10,00

l

aP

b a

l

b a aP

CK = 1,00

a) c)

b)

d)

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EWADE 2007 Komarov V.A.

New weight equation for definition of full wing mass and wing mass fraction

Specific size – square of wing in degree ½ -Specific load – lift

whence

Weight equation :

S

SgmnCG oK ⋅⋅⋅⋅=

**

*

SgmnGC

o*K

⋅⋅⋅=

gmnY ⋅⋅= 0

S gn Cm Kwing ⋅⋅⋅=σϕ Sg mn Cm oKwing ⋅⋅⋅⋅=

σϕ

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EWADE 2007 Komarov V.A.

Example of structural topology choice

3,563,032,682,832,752,692,553

1,981,891,831,811,781,761,682

2,071,941,841,711,701,681,621

δ = 0,4δ = 0,5δ = 0,6δ = 0,4δ = 0,5δ = 0,6

Strategy IIStrategy I

Panel structures

Membrane structuresWing

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EWADE 2007 Komarov V.A.

Example of morphing wingaerodynamic and weight efficiency research

Grant CRDF: REO-1386

24

1

4

c tip =

3

c root =

4

2 12

b/2 = 20

Axis of symmetry

6

24

2.19

35

4.38

7

2.38

7

4.77

4

Wing 1a

Wing 1b

Wing 2a

Wing 2b

Wing 3a

Wing 3b

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EWADE 2007 Komarov V.A.

Scheme of wing parts joints

2

Inner wing

Beam Outer wing

Rolls

Fuselage joints1

Rigid connection3

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EWADE 2007 Komarov V.A.

3rd idea. Using 3D-model with variable density

Model

Traditional material

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EWADE 2007 Komarov V.A.

.Hypothetic material with variable density

Algorithm of density distribution optimization

[ ]

0

01

1.2.

3.

i

ieqvi

i

constρσ

σρ σ

=

=

[ ] [ ]E E

σ ρ σρ= ⋅

= ⋅

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EWADE 2007 Komarov V.A.

Test

3D-model of the wing structurep

8-layers of 3D-solid finite elementsBoundary conditionsof console

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EWADE 2007 Komarov V.A.

Comparison of load-carrying factor coefficient calculations for thin-wall structure and 3D-solid model

with variable density

22.50 22.34 22.23 22.16 22.1122.7523.1423.8125.05

28.10

19.58

1820

222426

2830

1 2 3 4 5 6 7 8 9 10 11Iteration n

C K

s olid (8 layers )

As pec t ratio b /c = 8

w ing box

41.15 40.83 40.61 40.45 40.3541.6342.4143.73

46.1151.74

35.56

34363840424446485052

1 2 3 4 5 6 7 8 9 10 11Iteration n

C K

s olid (8 layers )

As pect ratio b /c = 12

w ing box

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EWADE 2007 Komarov V.A.

Wind tunnel model 1

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EWADE 2007 Komarov V.A.

Wind tunnel model 2with pressure of orifices

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EWADE 2007 Komarov V.A.

Spanwise load distributions

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EWADE 2007 Komarov V.A.

3D-model with variable density of material

X

Y

Z

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EWADE 2007 Komarov V.A.

External loads

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EWADE 2007 Komarov V.A.

Comparison of weight perfection

0,000

5,000

10,000

15,000

20,000

25,000

30,000

35,000

0 0,25 0,5 0,75 1

Morph

Trap

Morph for uniform load dis tribution

tc

C K

dim

ensi

onle

ss e

qviv

alen

t of w

ing

wei

gh

ge om e trica l pa ra m e te r of te le s cope wing

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EWADE 2007 Komarov V.A.

Comparison maximum aerodynamic efficiency

0.000

5.000

10.000

15.000

20.000

25.000

30.000

35.000

40.000

0 0.25 0.5 0.75 1

MorphTrap

L/D max

tc

max

imum

aer

odyn

amic

effi

cien

cy

geometrical parameter of te les cope wing

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EWADE 2007 Komarov V.A.

Pressurized cabin, pressure vesselSpecific volume – volume - VSpecific load– pressure – P

Some results for reservoirs:

Spherical –

Cylindrical –

Spherical from CM –

Cylindrical from CM –

VPGCK ⋅

=

23=KC

3=KC

3=KC

3=KC

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EWADE 2007 Komarov V.A.

ConclusionLoad-carrying factor allows:

1. To put in according to load-carrying scheme(topology of structure) the certain dimensionlessvalue which defines weight perfection of a design.

2. To build "weight" formulas for any designs.3. To accumulate the knowledge in convenient form

(dimensionless!) for analysis of existing and perspective designs.

There are 3 new ideas in the lecture, which can be usefulto increase efficiency of early stage design.

KC