Lecture #9
Analysis of fuselage frames using
the force method
FUSELAGE FRAMES
Airbus
A300
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FUSELAGE FRAMES - SURVIVABILITY
Boeing 737, Aloha Flight 243
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FUSELAGE FRAMES
Airbus
Beluga
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FUSELAGE FRAMES
Antonov
An-225
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FUSELAGE FRAMES
Airbus
A380
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FUSELAGE FRAME LOADS
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.
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FUSELAGE FRAMES ANALYSIS
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:
i  r  c  2  h  2  n  3  d  3  cc
cc – number of closed contours (cells)
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METHODS TO ANALYSE FUSELAGE FRAMES
Small degree
of statical
indeterminacy
Force method

Slope-deflection method
Slope-deflection method
in matrix formulation
Large degree
of statical
indeterminacy

Numerical methods
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EXAMPLE OF FORCE METHOD APPLICATION
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FLOWCHART OF SOLUTION USING FORCE METHOD
Classification
of the problem
Basic system
Loaded and
unit states
Canonical
equations
Redundant constraints are
removed
In loaded state, external load is
applied. In unit states, unit force
is applied instead of constraint.
Displacements corresponding to
removed constraints are
determined for each state
Forces in removed constraints
are determined
Total stress state
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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
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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?
For force method, I recommend
Kassimali. Structural Analysis. 3rd ed. 2005
Chapter 13
For fuselage frames, go to
Megson. An Introduction to Aircraft Structural Analysis. 2010
Chapter 5
… Internet is boundless …
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TOPIC OF THE NEXT LECTURE
Displacement methods
All materials of our course are available
at department website k102.khai.edu
1. Go to the page “Библиотека”
2. Press “Structural Mechanics (lecturer Vakulenko S.V.)”
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