Lecture #9Analysis of fuselage frames usingthe force method

Airbus A300

FUSELAGE FRAMES

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FUSELAGE FRAMES - SURVIVABILITY

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Boeing 737, Aloha Flight 243

Airbus Beluga

FUSELAGE FRAMES

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FUSELAGE FRAMES

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Antonov An-225

Airbus A380

FUSELAGE FRAMES

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FUSELAGE FRAME LOADS

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Typical loads acting on the fuselage frame are:

- distributed load due to inside pressure;

- concentrated forces;

- bending moments from wings;

- distributed shear load to balance shear forces.

FUSELAGE FRAMES ANALYSIS

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When analyzing fuselage frames, one must remember about:

- the usage of symmetry and anti-symmetry;

- internal pressure could be studied separately, basing on superposition principle;

- the internal statical indeterminacy due to the closed contour:

cc – number of closed contours (cells)

2 2 3 3i r c h n d cc

METHODS TO ANALYSE FUSELAGE FRAMES

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Slope-deflection method

Force method

Small degreeof statical

indeterminacy

Large degreeof statical

indeterminacy

Slope-deflection methodin matrix formulation

Numerical methods

EXAMPLE OF FORCE METHOD APPLICATION

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FLOWCHART OF SOLUTION USING FORCE METHOD

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Classificationof the problem

Basic system

Loaded andunit states

Redundant constraints are removed

In loaded state, external load is applied. In unit states, unit force is applied instead of constraint.

Canonical equations

Total stress state

Forces in removed constraints are determined

Displacements corresponding to removed constraints are

determined for each state

EXAMPLE OF FORCE METHOD APPLICATION

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EXAMPLE OF FORCE METHOD APPLICATION

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EXAMPLE OF FORCE METHOD APPLICATION

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EXAMPLE OF FORCE METHOD APPLICATION(NUMERICAL SOLUTION)

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EXAMPLE OF FORCE METHOD APPLICATION #2

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EXAMPLE OF FORCE METHOD APPLICATION #2(NUMERICAL SOLUTION)

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EXAMPLE OF FORCE METHOD APPLICATION #3

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EXAMPLE OF FORCE METHOD APPLICATION #3(NUMERICAL SOLUTION)

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WHERE TO FIND MORE INFORMATION?

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For force method, I recommendKassimali. Structural Analysis. 3rd ed. 2005Chapter 13

For fuselage frames, go to Megson. An Introduction to Aircraft Structural Analysis. 2010Chapter 5

… Internet is boundless …

TOPIC OF THE NEXT LECTURE

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Displacement methods

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

1. Go to the page “Библиотека”2. Press “Structural Mechanics (lecturer Vakulenko S.V.)”