1. Error How to prevent it?
Faulty strain gauge meter connected to the
aluminium quadcopter structure
Use a different, functional strain gauge
meter.
FEA limitations: positions A, B, C and D
read inaccurately from the von mises
analyses.
Read from a measured distance for each
analysis.
Discrepancy in the actual materials and the
FEA materials.
Ensure the same grade of materials is used.
Error during zero balancing. Take readings after the display is zeroed.
Points A,B,C and D not accurately defined Repeat the experiment.
Table 1 errors with improvements
The results taken for the strain gauge show a directly proportional relation
between load and strain. The Hooke’s law is obeyed.
When comparing the steel and aluminium structures, steel under successive
loading at both positions A-D and B-C yields a lower strain gauge reading than
compared to aluminium. This is largely due to the material properties of steel
inhabiting a much higher yield strength and modulus of elasticity than aluminium
which aid in minimizing strain along the cross-section of the material.
𝜎 = 𝐸𝜀
At points A-D loaded (D) ∴ 𝜎𝑠𝑡𝑒𝑒𝑙 = (209 ×109) ×(21 × 10−6)
= 4389000Pa = 4.389 MPa
∴ 𝜎𝐴𝑙𝑢𝑚𝑖𝑛𝑖𝑢𝑚 = (70 ×109)×(−24 ×10−6
)
=-1680000Pa = -1.6MPa
We can now safely conclude that steel is a stronger material than aluminium.
The results gathered from the experiment also comply with FEA results to some
extent as both aluminium and steel generate a liner trend for strain with increased
loading.
Figure 1Quadcopter structure
Date of laboratory: 25th
January 2016
103AAE Strain Gauge Experiment
GROUP ONE:
Kruti Joshi
Karolina Siemieniuk
Ismail Albalooshi
Michael Coopey
Rohan Birdee
Definitions
Methodology
Conclusions
Aim
To investigate the strain measurements on
a quadcopter structure and to compare the
results with simple FEA results.
Strain: The ratio of extension to original length.
Stress: The ratio of applied force to cross
sectional area.
Young’s modulus: the ratio of stress acting over a
material over the strain produced.
Tensile strength: The capacity of the material to
withstand loads.
Hooke’s Law: at the strain in a solid is
proportional to the applied stress within the elastic
limit of that solid.
1. Connect strain
gauge to the
steel
quadcopter
structure.
2. Auto balance
the strain gauge
meter. Ensuring
all values are
zeroed.
3. Add 500g
load to two
tips of the
quadcopter
diagonally.
4. Repeat
steps 2 &3
with 1000g,
1500g and
1700g loads.
5. Repeat
steps 3 &4
with the
other two
tips.
6. Repeat the
entire procedure
with Aluminium
quadcopter
structure. Figure 6 Von mises stress for Aluminium loaded at
points B amd C.
CES Edupack Values used for FEA:
Annealed AISI
5140 Steel
𝐸 = 209 𝐺𝑃𝑎
𝜎 = 260 𝑀𝑃𝑎
Poisson’s ratio = 0.285
Annealed
Aluminium 5052
𝐸 = 70 𝐺𝑃𝑎
𝜎 = 66 𝑀𝑃𝑎
Poisson’s ratio = 0.33
0
10
20
30
40
0 5 10 15 20
STRAIN[MICROSTRAIN]
LOAD [N]
FEA Points A-D loaded
STEEL A STEEL D
ALUMINIUM A ALUMINIUM D
0
10
20
30
40
0 5 10 15 20
Strain[Microstrain]
Load [N]
FEA Points B-C loaded
STEEL B STEEL C
ALUMINIUM B ALUMINIUM C
-10
0
10
20
30
0 5 10 15 20
STRAIN[MICROSTRAIN]
LOAD [N]
Points A-D loaded
STEEL A STEEL D
ALUMINIUM A ALUMINIUM D
Figure 2 Strain-load for points A and D loaded.
-10
0
10
20
0 5 10 15 20
Strain[Microstrain]
Load [N]
Points B-C loaded
STEEL B STEEL C
ALUMINIUM B ALUMINIUM C
Figure 3 Strain-load for points B and C loaded.
Figure 4 FEA strain-load for points A and D loaded. Figure 5 FEA strain-load for points B and C loaded.
Results and Discussion
 As the load increases the corresponding strain values increase too.
When points A and D are loaded:
Point D has greater strain than point A.
𝜀 𝑆𝑡𝑒𝑒𝑙 𝐴 , 𝜖 𝑠𝑡𝑒𝑒𝑙 𝐷, 𝜀 𝐴𝑙𝑢𝑚𝑖𝑛𝑖𝑢𝑚 𝐷 > 0.
𝜺 𝑨𝒍𝒖𝒎𝒊𝒏𝒊𝒖𝒎 𝑨 < 𝟎.
From Figure 4, it is safe to infer that for a particular load, Aluminium produces greater strain
than steel.
When points B and C are loaded:
𝜀 𝑆𝑡𝑒𝑒𝑙 𝐵 , 𝜖 𝑠𝑡𝑒𝑒𝑙 𝐶, 𝜀 𝐴𝑙𝑢𝑚𝑖𝑛𝑖𝑢𝑚 𝐵 > 0. 𝜺 𝑨𝒍𝒖𝒎𝒊𝒏𝒊𝒖𝒎 𝑪 < 𝟎.
From figure 5, we can infer that for a particular load, Aluminium produces more strain than
steel.
-40
-20
0
20
40
0 10 20
Strain[Microstrain]
Load [N]
Steel loaded at A-D
A
B
C
D
𝜺 𝑨 𝒂𝒏𝒅 𝜺 𝑫 > 𝟎
𝜺 𝑩 𝒂𝒏𝒅 𝜺 𝑪 < 𝟎 𝜺 𝑩 , 𝜺 𝑪 & 𝜺 𝑫 < 𝟎
-100
-80
-60
-40
-20
0
20
40
0 5 10 15 20
Strain[Microstrain]
Load [N]
Aluminium loaded at A-D
A
B
C
D
𝜺 𝑨 > 𝟎
Potential Errors
References:
Campbell, F. (2206). Manufacturing Technology for Aerospace structural materials. Great
Britain: Elsevier.
2016, February 26). Retrieved from http://hyperphysics.phy-astr.gsu.edu/hbase/permot2.html