Lecture #2 Historical progress of aircraft structures. Structural layout and design models

Lecture #2Historical progress of aircraft structures. Structural layout and design models

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But, the one type of load was still not used in large-scale structure:• Torsion.

At the start of 20-th century engineers already knew how to deal with:• Tension and compression;• Bending;• Buckling.

HISTORICAL PROGRESS OF AIRCRAFT STRUCTURES

Thus, the history of aircraft structures is the history of engineering efforts against torsion and, partially, buckling.

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Forth Bridge, built 1890

Bending was already well-studied in bridges:



Flyer 1903, Wright brothers, USATake-off mass 283 kg, wingspan 12 m

1903-1920. Truss structures, unstressed skin

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Ilya Muromets, Russian Empire, 1913Take-off mass 7 000 kg, wingspan 31.1 m

1903-1920. Truss structures, unstressed skin

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Steen Skybolt, 1970aerobatic biplane

Truss airplane structures used nowadays


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Fokker D.VIII, Germany, 1918Take-off mass 605 kg, wingspan 8.3 m

First well-documented problem with torsion


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Quarter-chordline

How the nature solves the problem of torsion


1920-1930. Monoplanes and corrugated skin introduced

Tupolev TB-3, Soviet Union, 1932Take-off mass 19 500 kg, wingspan 39.5 m

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KhAI-1, Soviet Union, 1932Take-off mass 2 600, max. speed 324 km/h

1920-1930. Aerodynamic requirements become tougher

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1930-1940. Aluminium extensively used, stressed skin.Method of reduction coefficients developed (1932).

Messerschmitt Bf.109, Germany, 1935Take-off mass 3 375 kg,max. speed 720 km/h

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1940-1950. Sweptback wings, thick stressed skin, thin-walled beam structure.

Mikoyan-Gurevich MiG-15, Soviet Union, 1949Take-off mass 4 917 kg, wingspan 10 m

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Mikoyan-Gurevich MiG-21, Soviet Union, 1959Take-off mass 10 100 kg, max.speed 2230 km/h

1950-1960. Triangle wings, specific passenger aircraft. Rise of fatigue, vibration and aeroelasticity problems

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De Havilland DH.106 Comet, Great Britain, 1949Take-off mass 73.5 ton, wingspan 35 m 14


Antonov An-10, Soviet Union, 1957Take-off mass 51 ton, wingspan 38 m


15Crashed due to fatigue at 1972


Lockheed L-188 Electra, USA, 1957Take-off mass 51 ton, wingspan 30 m


16Crashed due to propeller flutter at 1960


1960-1970. Variable sweep wings, new heat-resistant materials. Rise of passenger fleet.

Mikoyan-Gurevich MiG-23, Soviet Union, 1967Take-off mass 20 100 kg, max.speed 2500 km/h

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1970-1980. Wide-body passenger aircraft

Boeing 747, USA, 1969Take-off mass 340.2 ton, wingspan 59.6 m

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1980-1990. Extra-large cargo aircraft

Antonov 124, USSR, 1982Take-off mass 402 ton, payload 150 ton, wingspan 73.3 m

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1990-nowadays. Wide use of new materials (composite materials, titanium alloys)

Boeing 787 Dreamliner, USA, 2009Take-off mass 245 ton, wingspan 60 m

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Modern tendencies

Bell Boeing V-22 Osprey, first flight 1989, introduction 2007

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Actively-controlled aircraft: multicopters etc.


Solar Impulse 2, 2014, take-off mass 2300 kg,Wingspan 72 m

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Electric aircraft

Modern tendencies

GOALS AND OBJECTIVES

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The goal of structural analysis is to get the efficient structure and verify its fitness for use.

Structural analysis is the determination of the effects of loads on physical structures and their components.

As a science, structural analysis covers principles and methods of strength, rigidity and stability calculations.

FLOWCHART OF STRUCTURAL ANALYSIS

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Real object

Structurallayout

Design model

Only load-carrying structureis kept

Assumptions and simplificationsare applied, loads are calculated

according to the problem

Results ofanalysis

Implementationon real object

This step is beyond the scopeof structural analysis

Structural analysis


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Real object

Structurallayout

Design model

Results ofanalysis



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Real object

Structurallayout

Design model

Results ofanalysis



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Real object

Structurallayout

Design model

Results ofanalysis


Depending on the kind of problem which is solved, the design model could be either as detailed as structural layout, or as generalized as below:

METHODS OF STRUCTURAL ANALYSIS

Analytical methods Numerical methods

Best for designing calculations, suit for

checking calculations with certain limitations

Best for checking calculations, practically

effete for designing calculations

Solutions exist for partial cases (specific objects)

Versatile and flexible

Need much work to be developed, but only simple software for

application

Need expensive and complex software and

hardware28

METHODS OF STRUCTURAL ANALYSIS

Analytical methods Numerical methods

Methods of Mechanics of Materials, methods for statically indeterminate structures (method of

forces, method of displacements), beam

theory, method of reduction coefficients etc.

Finite Element Method (FEM, best for solid

mechanics),

Finite Difference Method (FDM),

Movable cellular automaton (MCA, best for

fracture, crack propagation) etc.

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TOPIC OF THE NEXT LECTURE

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Introduction to buckling

DEPARTMENT LIBRARY

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All materials of our course will be availableat department website k102.khai.edu

1. Go to the page “Библиотека”

2. Press “Structural Mechanics (lecturer Vakulenko S.V.)”

http://k102.khai.edu/

http://k102.khai.edu/ru/site/library.html

http://k102.khai.edu/ru/site/structural-mechanics.html



Lecture #2 Historical progress of aircraft structures. Structural layout and design models

Documents

takeoff mass

history of aircraft

specific passenger aircraft

soviet union

truss structures

triangle wings

rise of fatigue

rise of passenger fleet