Department Of Mechanical Engineering And Manufacturing
Faculty Of Engineering And Built Environment
Universiti Kebangsaan Malaysia
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Topic
Lecturer
: Fans Blade
: -Dr. Nashrah Hani Binti Jamadon
- Dr. Intan Fadhlina Binti Mohamed
Group
: Group 6
Submission Date :
NAME
MATRIX NO
Kugan A/L Ayyakannu
A189174
Nur Sofea Lissa bt. Isahrin
A188911
Ayu Safiah Bt Mohamad Aris
A188984
Alya Adriana Binti Noorizal
A188605
Mohamad Alif bin Rozani
A188480
1.0 INTRODUCTION
In this project, the components that we choose for material selection is fan blade. Fan blade is defined
as blade of a rotating fan. Besides that, it also defined as one of the specially shaped rotating parts
(blades) of a mechanical fan which move and distribute air. The fundamental purpose of a fan blade
is to push air downward, generating a downward raft and cooling the room. As a result, these blades
can either push air upwards into the fan or downwards toward the floor. For your information, fan
blade also can be used in aero planes. The majority of flights use turbofan engines to create thrust
because they are more efficient and also save fuel. The core compressor, core turbine, and fan blades
make up a turbofan engine. With the assistance of front fan blades, the energy contained in gas is
transformed to kinetic energy. The turbine has a revolving disc, blades, and nozzle guide vanes, just
as the compressor. The first and most important component of a turbofan engine is the front fan
blade. With the help of a big spinning fan, a significant volume of air is sucked into the turbine. The air
is sped up and split into two halves by the fan blades.
Based on their common functions in real life, we are going to do a research on what would be the best
material for fan blades. Therefore, we are going to discuss about candidates that need to be consider
before doing material selection process. After that, we will list the candidates of materials which is
suitable to used in jet or aeroplane engine as well compare each other with respect to their properties.
Lastly, the most suitable material will be chosen to build a perfect fan blade in airplanes and jets as
well.
2.0 HYPOTHESIS
There are 2 types of properties that we use to do the comparison which are mechanical properties
and general properties and under these two types of properties, we have several criteria’s that we
consider during the material selection.
Mechanical properties: Tensile Strength (MPa)
Young Modulus (GPa)
Fracture Toughness (MPa m^0.5)
General properties: Density (kg/m^3)
Cost (RM/kg)
3.0 TABLES, ANALYSIS AND GRAPH
Table 1 below shows the comparison of mechanical properties (tensile strength, Young Modulus &
fracture toughness) and general properties (cost & density) between 3 materials which are cast
aluminum alloy, titanium alloy and carbon-fiber-reinforced polymers (CFRP)
Cast Aluminum Alloy
Titanium Alloy
CFRP
Tensile strength
(MPa)
193-341
763-1.19e3
550-1.05e3
Young modulus
(GPa)
69-76
110-120
69-150
Density (kg/m^3)
2.65e3 - 2.77e3
4.43e3 – 4.79e3
1.5e3 – 1.6e3
Fracture toughness
(MPa m^0.5)
19-30.9
51.3-86.1
6.12-20
Cost (RM/kg)
8.35-9.06
106-116
158-176
Table 1
Diagram 1
Diagram 1 shows the Young modulus (GPa) vs density (kg/m^3) graph based on the CES Edupack
2021. As we can see there are several materials in high Young Modulus and low density regions
which are CFRP, aluminum alloy and titanium alloy. Titanium alloy and CFRP have slightly high Young
Modulus compared to the cast aluminum alloy. For density, we can see CFRP has the lowest density
compared to both titanium and cast aluminum alloy.
Diagram 2
The graph in diagram 2 shows that titanium alloy has the highest tensile strength followed by CFRP
and cast aluminum alloy. The higher the tensile strength will produce components that can withstand
higher pressure to avoid fracture or stretch easily the goal of this project is to create a composite fan
blade and do structural analysis and optimization on it. To achieve the perfect fan blades, we need to
consider the system applied in the engine. Aero engine manufacturers produce turbofans with higher
bypass ratios to attain higher fuel efficiency, which can only be achieved with larger and heavier fan
sections. The pressure in the engines system which makes the higher tensile strength is what the
material needed to resist before breaking.
Diagram 3
Diagram 3 shows the fracture toughness (MPa.m^0.5) vs density (kg/m^3) graph. Based on
this, materials that have high fracture toughness with low density are CFRP, aluminum alloy
and titanium alloy. As we can see, CFRP has the lowest value of both fracture toughness and
density properties.
Diagram 4
It is important to consider the price too because to ensure the product is easily reachable to the
users. After recording the price range for all the materials, we set the limit between (8.35-176)
MYR/kg so that we could analyze the chosen material specifically in details. Diagram 4 shows that
aluminum alloy is the cheapest compared to titanium alloy and carbon fiber reinforced polymer
(CFRP). The second cheap material is titanium alloy which has an average price of 111 MYR/kg. For
carbon fiber reinforced polymer (CFRP), it has an average price 167 MYR/kg. According to the graph
we got from CES software, we can conclude that cast aluminum alloy and titanium alloy are
affordable and the density of both materials also have no much difference with CRFP even though it
is the lightest.
4.0 DISCUSSION
Here are some reasons why we need high Young modulus, tensile strength and fracture toughness
with low density materials.
1. High Young Modulus – High stiffness material is a must to prevent torsional distortion from
occurring as it can damage the fan blade. Furthermore, with stiffer material it allows us to
design the fan blade to be longer and thinner. Longer and thinner fan blades are better as it
is more aerodynamic and lightweight. High stiffness material also results in much tighter
tolerances which is the ability to produce components with strict design parameters. The
tight tolerance ensures the part of the fan blade to work optimally and at the same time
increases the fan blade’s performance. Thus, making only fewer blades are needed instead
of many blades.
2. High tensile strength – The higher the tensile strength will produce components that can
withstand higher pressure to avoid fracture or stretch easily due to its centrifugal force.
3. High fracture toughness - Fracture toughness is a material resistance to crack propagation.
High fracture toughness is required in designing the fan blade of an aircraft due to high
stress applied when flying. To avoid any complication that can occur to the fan blades, high
fracture toughness helps in resisting such high stress or other foreign objects like bird
strikes.
4. Low density – The material should have a low density because the aircraft's fan blades are
one of the heaviest components in the aircraft structure. The density of the fan blade should
be in the middle, which means it should not be too light because this will disrupt the fracture
toughness feature and it also cannot be too heavy, as this will put the aircraft at a
disadvantage. The density of the material has a significant impact on fan blade efficiency. As
a result, the lighter the fan blades, the faster it spins. Furthermore, a lighter fan blade will
also save fuel consumption and allow for a larger fan blade in an appropriate weight range.
Table 2 below show the summary of the material properties comparison between the cast
aluminium alloy, titanium alloy and CFRP from the charts above:
Cast Aluminium Alloy
Titanium Alloy
CFRP
Durability
Low
High
Medium
Stiffness
Low
High
Medium
Weight
Medium
Heavy
Lightweight
Fracture toughness
Medium
High
Low
Cost
Low
Medium
High
Table 2
4.1 CALCULATIONS
By using 4 steps which are translation, screening, ranking and documentation we can determine which
material that is suitable. We will use the performance equation for tensile strength and fracture
toughness as an example. Crack size is the length at which a crack becomes unstable
Translation
Given that the fracture toughness formula is 𝑲 = √(𝝅𝜶) and the tensile stress (𝝈) scale and with
the density (𝝆) of material is 𝝈= 0.11𝝆 Increasing crack size will increase the fracture toughness and
the ductility of the material.
Objective: Maximize the value of crack size
By rearrange the equation we get
𝜶=
𝒌𝟐
𝝈𝟐 𝝅
and we need to substitute
𝝈 = 0.11𝝆 inside
the
formula.
We get 𝜶
=
𝟏
𝟎.𝟎𝟏𝟐𝟏𝝅
need to maximize
𝒌
× ( )𝟐 our performance equation. As we can see, to maximize a, we simply
𝝆
𝒌
𝝆
5.0 RATIONAL
According to the data shown above in table 2, titanium alloy is the most durable of all the materials.
This material can withstand greater high-speed rotation and allowing more air to be pushed
backward into the engine and enable the turbine blades to generate electrical energy more
effectively. Additionally, the material is capable of withstanding significant tensile strength caused
by centrifugal force, with the fan blades rotating 10,000 times (1 start-stop cycle every flight) due to
a tensile strength of 976.5 MPa on average.
Furthermore, CFRP is stiffer than cast aluminium alloy. The average Young's Modulus values for CFRP
and Cast Aluminium Alloy are 109.5 GPa and 72.5 GPa, respectively. The fan blades are intended to
endure lateral vibrational stresses caused by air turbulence and system excitation. As a result, to
prevent vibrational fatigue, the stiffness of the material should be kept as high as feasible. The fan
blades must also be built of high-strength material in order to avoid torsional distortion, which might
fracture the fan blade easily. Nevertheless, titanium alloy has the greatest Young's modulus of the
three materials, with an average of 115 GPa. This material works the best to distort the fan blades
back to their original shape after being struck many times.
The density of fan blades, on the other hand, is the most crucial component in the aircraft's design
because if the fan blades are too heavy, it will affect the total mass of the aircraft, making it difficult
to fly. Among all the materials, CFRP is the lightest. However, the fan blades should not be too light
since they will become brittle and cannot sustain excessive tension. The fan blades should be made
of a medium-weight material so that they can rotate as rapidly as possible and accelerate a large
volume of air into the engine, allowing the turbine to generate more electrical energy in a shorter
length of time.
The fracture strength of titanium alloy, cast aluminium alloy, and CFRP is 68.7 MPa/m0.5, 24.95
MPa/m0.5, and 13.06 MPa/m0.5, respectively. The fracture toughness of titanium alloy is the
greatest of the three materials, according to this analysis. As a result, titanium alloy has the highest
strength to withstand further fracture, even in the absence of cracks in the material. The fan blades
will take longer to break this way. For example, if the fan blades have fracture while flying in the air,
it is still safe to use because the likelihood of the fan blades breaking in the meantime is negligible.
When it comes to CFRP fan blades, it's risky to utilise them if they're cracked since they cannot
sustain the fracture.
In terms of cost, CFRP is the most expensive, costing an average of RM167 per kilogram. This is
because carbon fibre production is a very specialised process. As a result, not just anybody can work
in the carbon fibre industry. Carbon fibre production machinery is also sophisticated. This equipment
can cost thousands of dollars, causing the product's price to rise. Cast aluminium alloy, on the other
hand, is the most affordable of all since it is one of the most abundant materials on the world. It is
easy to find.
In our opinion, the best option will be titanium alloy fan blades. This is due to the fact that titanium
alloy is tough and can resists creep. Even if a bird accidentally hides it or any other object, the fan
blades will not be readily broken. As we all know, aeroplanes are mostly utilised in the air, exposing
the fan blades to the sunlight and rain. Rainfall with a pH value of less than 4 is common, especially
in industrial areas. Since the aircraft fly in and between the clouts, which are the closest to the rains,
the fan blades will rust quickly. Titanium alloy fan blades, on the other end, have a high corrosion
resistance and will not rust easily. Titanium alloy is the heaviest of the three materials in terms of
weight. The density of the fan blades, on the other end, should be in the medium range to prevent
the blades from breaking easily. Titanium alloy fan blades have the greatest ability to endure high air
tension. The density of titanium fan blades should not be used as a justification to reject using the
material for safety concerns. Furthermore, the cost of titanium alloy fan blades is within a
reasonable range, which will reduce the overall cost of the aircraft.
6.0 CONCLUSION
Material selection has to be one of the most important processes in the design of fan blade.
Selecting the most suitable material involves seeking the best match between the design
requirements of the fan blade and the properties of the materials. From the observation and the
result obtained, the conclusion can be drawn in the report is that titanium alloy is the best material
for manufacturing fan blade compared to cast aluminium alloy and carbon-fibre reinforced polymer
(CFRP). Titanium alloy is chosen because it fulfils all the constraints in both function and
performance for a fan blade. Material selection is made considerably easier with the help of CES
Edupack software since the materials are split accurately according to their qualities. The most
appropriate materials may be simply selected based on the attributes that our organisation has
determined to be important, such as density, tensile strength, fracture toughness, Young modulus
and pricing.
1
7.0 REFERENCES
References
Aeroengine Composites, Part 2: CFRPs expand. (2015, August). ginger gardiner.
https://www.compositesworld.com/articles/aeroengine-composites-part-2-cfrps-expand
B.F.S., J.W.H., P.B., & K.B. (2010). Blade materials, testing methods and structural
design. Bent F. Sørensen.
https://www.witpress.com/Secure/elibrary/papers/9781845642051/9781845642051013FU1.p
df
CES EduPack. (2009, March).
https://www.yumpu.com/en/document/read/18639496/projects-using-ces-edupack-maelabsucsd
Materials for Aircraft Engines. (2015). TAKEHIRO OKURA.
https://www.colorado.edu/faculty/kantha/sites/default/files/attached-files/73549-116619__takehiro_okura_-_dec_17_2015_1027_am_-_asen_5063_2015_final_report_okura.pdf
Progress in Aerospace Sciences. (2013, July).
https://www.sciencedirect.com/science/article/abs/pii/S0376042112000838
Strength Assessment of Fan Blade with Different Materials. (2019, February).
https://www.researchgate.net/publication/330992628_Strength_Assessment_of_Fan_Blade_
with_Different_Materials
Tomas Kellner. (2016, April). The Art of Engineering: The World’s Largest Jet
Engine Shows Off Composite Curves. https://www.ge.com/news/reports/the-art-ofengineering-the-worlds-largest-jet-engine-shows-off-composite-curves