Structures of an aircraft can be categorised as primary structural components and secondary structure components. Primary structure components are the components which lead to failure of the aircraft if such component is failed during the flight cycle. Secondary components are load sharing components in an aircraft but will not pave the way to catastrophic failure. Designing aircraft structures should follow several strategies to assure safety. For that, there are three main methods used in designing and maintenance procedures. First one is the safe flight, which an aircraft component has a lifetime. That component is not used beyond that limit and should replace though it is not failed. The fail-safe method is another one that redundant systems or components are there to ensure there is another way to carry the load or do necessary control. The final one is the damage tolerance which measures the current damages are within acceptable limit and carry out the main functions until the next main maintenance process. To determine the safety of a structure component load distribution, stress and strain variation, deflection can be used as parameters to make sure that component can withstand maximum allowable load with safety factor. There are several techniques used to get accurate results as numerical methods, Finite Element Method (FEM) and experimental methods. In the design process, those three steps are followed in an orderly manner to ensure the safety of an aircraft.

1. K.M.G.L. Dilshan
150131A
Experimental and Numerical Analysis
of a Rectangular Wing Structure
M E 4 1 5 0 – A i r f r a m e St r u c t u r e s a n d
D e s i g n
1

2. 2

3. 3

4. Procedure:
1. Move complete unit to required position
2. Mount the wing to the setup
3. Remove any sag in the system
4. Connect strain Bridge Controller to the
setup
5. Turn on the Strain Bridge Controller and
wait couple of minutes
6. Take readings at unloaded condition for
each strain gauge
7. Position the load cell under the middle of
front spar. Tight the friction lock
8. Apply load to the system by rotating crank
handle
9. Take readings at loaded condition after
values get steady
10. Repeat the process for the rear spar loading

5. Procedure:
1. Measure the critical components of the wing
geometry used in the experiment
2. Model the geometry using CAD software
(SOLIDWORKS 2018)
3. Import the geometry to a simulation
software (ANSYS Static Structural Analysis)
4. Define material properties (Aluminium
6061-T6)
5. Define boundary conditions
6. Apply load to the front spar
7. Complete the simulation
8. Repeat the process after applying force to
the rear spar
9. Get results for the analysis

6. 6
Mesh view Assembly

7. 7
Mesh view Spars and Ribs
Details
• Nodes – 400444
• Elements – 57330

8. 8
Mesh view Skin
Details
• Nodes – 95969
• Elements – 45260

9. 9 9
Total Deformation
Spars and Ribs

10. 10 10
Total Deformation
Spars and Ribs

11. 11 11
Shear Stress (XY plane)
Spars and Ribs

12. 12 12
Shear Stress (YZ plane)
Spars and Ribs

13. 13 13
Shear Stress (XZ plane)
Spars and Ribs

14. 14 14
Maximum Shear Stress
Spars and Ribs

15. 15 15
Maximum Shear Stress
Skin

16. 16 16
Maximum Principal Stress
Skin

17. 17
Loaded Spar Minimum Strain value Maximum Strain Value
In Spar In Skin In Spar In Skin
Front Spar -0.000144157 -0.000102062 0.000131438 0.000072733
Rear Spar -0.000094409 -0.000086754 0.00008677 0.000061248
Loaded Spar Minimum Stress value Maximum Stress Value
In Spar In Skin In Spar In Skin
Front Spar -9932417 Pa -7032072 Pa 9056078.2 Pa 5011303.7 Pa
Rear Spar -6504780 Pa -5977351 Pa 5978453 Pa 4219987 Pa
Experimental Results
Experimental and Simulation Results
Loaded Spar Experimental value Simulated value
Front spar 34 mm 2.46 mm
Rear spar 41 mm 2.51 mm

18. 18
Strain
Gauge
Arrangement
Strain gauge Front spar loading –
stress – Mpa
Rear spar loading –
stress – Mpa
G -7.032 -5.977
J 5.011 4.220
Strain gauge Front spar loading –
stress – Mpa
Rear spar loading –
stress - MPa
F -1.758 -4.044
K 0.879 2.637
Strain gauge Front spar loading –
stress – Mpa
Rear spar loading –
stress - MPa
H -5.538 -2.022
I 3.165 1.143

19. FACTS

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