MECN4002 – Aircraft Structures II
Assignment 2012
A fuselage frame of a pressurised aircraft with a “double bubble” cross section
experiences structural failure. The tie-bar connecting the “corners” of the section fails
and the frame is thus required to carry the internal pressure within the fuselage by
means of bending. The outer surface of the frame comprises two identical circular
arcs of radius 3000mm. The depth of the section varies linearly between points A and
B. The geometry of the frame is shown below.
A
hA
γ
B
P
hB
R
The frame is manufactured from aluminium alloy 2014-T6. The frame has a constant
thickness of 50mm. The effective internal pressure on the frame has a magnitude of
5.0 bar.
i)
Find the maximum tensile stresses at point A and the change in vertical and horizontal
dimensions of the frame through points A and B respectively using the finite element
method.
ii)
Use complementary energy methods to obtain the results of question i) above.
iii)
Compare the results obtained from the two methods.
iv)
Explain any differences between the results of the two methods of analysis.
The dimensions of lengths hA, hB and γ are shown overleaf:
Student
hA
hB
γ
Biobaku ¸ Ayodimeji
Davidson ¸ James D
Haupt ¸ Richard J
Kalian ¸ Nimesh
Keeka ¸ Hemansu K
Leering ¸ Mitchell P
Mangoro ¸ Pitso N
Mlimo ¸ Vinkie V
Moletsane ¸ Atlarelan
Msibi ¸ Lumka
Mubayiwa ¸ Nkosinomus
Mulaudzi ¸ Fhulufhedz
Muloongo ¸ Jason
Munilall ¸ Nitesh
Naidoo ¸ Kuveshen
Nair ¸ Duran
Nedzanani ¸ Arehone
Nel ¸ Lara J
Nkoana ¸ Masingila L
Sayedabdurrahaman ¸ A
Segone ¸ Ephraim M
Smit ¸ Teubes C
Tahilram ¸ Poonam
Thavhanyedza ¸ Mpho
Thomas ¸ Joseph
Wadee ¸ Ahmed
50
100
150
200
50
100
150
200
50
100
150
200
50
100
150
200
50
100
150
200
50
100
150
200
50
100
150
200
50
100
150
200
50
100
150
200
50
100
150
200
50
100
150
200
50
100
150
200
50
100
150
200
55
55
55
55
65
65
65
65
75
75
75
75
85
85
85
85
95
95
95
95
105
105
105
105
125
125
This assignment counts 15% towards the total mark for this course. Parts i) through
iii) of the assignment carry equal weighting.
Submission of the assignment is broken into two parts:
The solution to part i) of the assignment must be posted in the box outside Room
110A before 16:30 on a date mutually agreed between the class and the lecturer, but
no later than the end of the week in which the second teaching block commences.
Late submissions will not be accepted.
The solution to parts ii) and iii) of the assignment must be posted in the box outside
Room 110A before 16:30 on a date mutually agreed between the class and the
lecturer. The lecturer will retain the submissions of each student for part i) of the
assignment and part iii) of the assignment will be marked using this information. Late
submissions will not be accepted.
NB: This assignment is used to assess ECSA ELO 5. Please read the appendix to
the course outline to familiarize yourself with the assessment criteria for this
ELO, and the consequences of not achieving the ELO.