Material Selection for a Jet-Ski Steering Hub: Project

This project report details the material selection process for a jet-ski steering hub, a critical component connecting the steering rod to the watercraft's body. The project begins by outlining the function of the steering hub, load conditions, and necessary attributes, followed by a translation of user-based objectives into material-oriented objectives. The report then describes the screening process using a CES database, focusing on material properties such as Young’s modulus, specific stiffness, tensile strength, yield strength, and durability in both fresh and saltwater environments. The report also considers factors such as price and weight. The project continues with ranking materials based on these objectives, analyzing competing constraints, and considering manufacturing processes. The final section provides recommendations and conclusions regarding the optimal material choice for the steering hub, emphasizing the importance of balancing mechanical properties, durability, and cost-effectiveness. The report provides a detailed breakdown of each step in the material selection process, offering a thorough analysis of the factors involved in choosing the best material for this specific application.

STEERING HUB FOR JET-SKI
NAME
STUDENT NUMBER

CONTENTS
LIST OF FIGURES......................................................................................................... 2
EXECUTIVE SUMMARY................................................................................................. 3
INTRODUCTION........................................................................................................... 4
Load conditions....................................................................................................... 4
Function of the steering hub...................................................................................4
Other necessary attributes...................................................................................... 5
TRANSLATION............................................................................................................. 5
SCREEENING............................................................................................................... 6
RANKING AGAINIST PRIMARY OBJECTIVES................................................................11
COMPETING CONSTRAINTS OR MULTIPLE OBJECTIVE ANALYSIS OR SHAPE ANALYSIS
................................................................................................................................. 14
PROCESSING AND MANUFACTURE............................................................................14
FINAL RECOMMENDATIONS AND CONCLUSIONS......................................................16
CONCLUSION......................................................................................................... 16
RECOMMNDATIONS............................................................................................... 17
REFERENCES............................................................................................................ 17
LIST OF FIGURES
Figure 1. price parameter........................................................................................... 7
Figure 2. Selected mechanical properties..................................................................8
Figure 3. Selected durability....................................................................................... 9
Figure 4. materials passed all steges.......................................................................10
Figure 5. Chart for yield strength.............................................................................10
Figure 6. shape selection.......................................................................................... 15
Figure 7. Process characteristics..............................................................................15
Figure 8. Economic attributes...................................................................................15

EXECUTIVE SUMMARY
There are various key components in a jet-ski water craft. One of the most
important component is the steering hub. The steering hub connects the steering
rod to the body of the raft. The materials used to create such a component should
thus be selected carefully. This is achieved by converting the user based objectives
to actual material oriented objectives and creation of a material index. One has also
to consider the process of manufacturing the part. One has to understand the
material properties and their machinability of production using certain method. All
this is achievable on a material and process section software such as CES.

INTRODUCTION
A water-raft’s steering wheel is a piece of the steerage that interfaces with a
mechanical, electric, or pressure driven system to help with turning the vessel.
Water raft with detachable engines steer with a wheel which pivots the whole drive
unit; inboards at times utilize a case with a connected propeller; individual
watercraft utilize stream drives with an impeller to constrain water into a spout that
the administrator can go to the ideal course. Some cutting edge ships supplant the
wheel with a flip that remotely controls an electric or water driven rudder drive, with
a marker that shows the rudder point progressively to the helmsman.
Notwithstanding the steering framework utilized on a vessel, you should seriously
mull over as a one-day rental or an all-inclusive contract, it is a smart thought to
realize what sort of framework the pontoon utilizes, to see how it works, the area of
framework parts, and to have the option to make straightforward fixes if the
controlling leads you adrift while in progress.
Steering frameworks comprise of a wheel, rudder, guiding link, and link
associations, all connecting the wheel to the motor. The most significant part is the
steerage, which changes over a wheel's turning movement into a push-pull
movement on the link, at last moving the propeller right, left, or to amidships.
Load conditions
Nonetheless, the steering hub which is one of such parts is inclined to experience
the ill effects of the vertical, flat and sidelong powers following up on the
suspension framework when the street surface is loaded up with potholes and other
blocking conditions that will incite such powers on the vehicle suspension
framework. The in-administration stacking state of a vehicle attach hub presented
to such landscape will slowly wear off, loosen and bomb over the long haul if fitting
investigation isn't done. The heap following up on the suspension get together can
be characterized regarding a co-ordinate framework. According to the heaps
following up on the suspension framework, it tends to be said that the steering hub
will be exposed to loads from all the bearings as appeared in Figure 2. The stacking
conditions required for the steering bar investigation condition is as for the co-
ordinate arrangement of the steering hub alone and not of the entire suspension
framework. The steering bar co-ordinate framework is as per the following;
a) X-direction is radially outward on a level plane
b) Y-direction is radially outward vertically
c) Z-direction is along the length of the bar
Be that as it may, the bind bar is exposed to stacking conditions which changes in
bearing, generally tangential and normal stresses, normally referred to the normal
stresses (σ) and tangential shear stress (τ), communicated in Newton per square
meter (N/m2).
The part should have a high life time. The part should be durable. The part should
also be usable in both hot and cold climates. (Hammond, 2006).

Function of the steering hub.
The steering hub holds the steering wheel into positon while at the same time
permitting rotation of the steering wheel or handle and the rod. It is fixed onto the
water ski body.
Other necessary attributes.
Other than the mechanical properties, the steering hub needs to be corrosion
resistant. The boat is most likely to be used in sea water where the water is salty
and very corrosive. Also, the steering hub need to be light weight to reduce the
weight of the jet-ski. Light- weight materials are preferred on such application to
enable the boat to float on water. Most importantly, the piece need to be cheap.
The material used should have a low cost per kilogram. The process of
manufacturing should be readily available as well as cheap. (T.E. Norgate, 2004).
Other properties are based on the aesthetics, ergonomics and safety. The part
should be comfortable to handle while operating. The shape should not cause
injuries when using or when installing.
TRANSLATION
Function To facilitate the steering of the water craft by
transferring the motion from the steering wheel to the
rotation pinion of the funnel.
Constraints Axial forces
Radial stresses
High torque
Fatigue stresses
objectives a) High Yield strength
b) High tensile strength
c) High Young’s Modulus
d) High specific stiffness
e) Low price
f) Acceptable to excellent durability with fresh and
salty water
g) Low density
Free variables size
The object specific objective of being strong calls for a material with high Young’s
modulus, high specific stiffness, high tensile strength and high yield strength. The
Young’s modulus communicates the ability of a material to withstand the axial
stresses on the steering hub without failure. The material for this part should be
able to withstand high stresses which are induced by the strains. A material with
high Young’s modulus for this application implies that the steering hub I able to
handle the large steering forces without tearing.
The material property of having high specific stiffness will enable the steering hub
to resist changing in shape when the steering wheel is turned. In this application,

the need of a material with high flexibility, which is actually the opposite of specific
stiffness is not appropriate since flexing parts in the steering assembly might
remove interfere with key and steering shaft alignment. It might compromise with
the handling of the steering handles and safety.
One of the most important aspect depicting on the durability of the material is the
tensile strength. This is the amount of tensile strength expressed in Pascal the
material is capable of withstanding until complete rapture. Some materials can do
well in compression but poorly in tension. During skiing, there is a tendency of the
skier to lean backwards thus pulling the steering handle outward creating a tension
force on the steering handle and the components attached to it. As a result, high
tensile materials are more suited in this application.
Perhaps the most important property depicting strength is the yield strength. Yield
strength refers to the ability of a material to resist forces without yielding. The
difference between the tensile strength and the yield strength is that yield strength
occurs when the specimen or part immediately starts to crack deform irreversibly
while the tensile strength refers to the total rapture of the specimen. For most
metals, the yield strength is usually estimated as 75% the tensile stress. (Pilz, H,
2005).
Other than strength, durability is one of the specific objective for this part as
indicated in the previous section. This specific objective can be translated to
material properties such as its reaction with water, organic solvents, oxidation etc.
For this application, the durability in both the fresh and water has to be either
acceptable or excellent. Since the part is not expected to be used on acids, organic
solvents or alkalis, the durability in this environments can be of limited use.
The part need to be light weight. Materials used in water crafts and rafts have to be
light and of low density to enable float on water. They also need to be resistant
against fracture.
The last objective is related to the price of the part. A part which is made of less
expensive materials is likely to sell at a lower price than that made from expensive
materials. The material prices obviously translate to the overall price of the design
hub. (Alloy Digest, (2001).
The material objectives can thus be listed as shown below.
a) High strength
i. High Yield strength
ii. High tensile strength
iii. High Young’s Modulus
b) High specific stiffness
c) High fracture toughness
d) Low price
e) Acceptable to excellent durability with fresh and salty water
f) Low density

SCREEENING
Screening was done on CES database 3. The said material objectives were inserted
in the material chart select. The first objective inserted in the chart select was the
price. I chose a maximum 20£/ kg to be the maximum.
Figure 1. price parameter
The other objectives were the mechanical properties of the materials. The Young’s
modulus was set between 50 to 250 GPa. Since the steering is expected to be
turned by hand, lower forces are expected. The turning forces for most according to
Yokohama are below 450 N. As a result, I constrained my charts to a value that is
not too small to cause failure or too big to render the part over-engineered. I
inserted values of 50 GPa and a maximum value of 250 GPa. Most elastomers are
eliminated using this property as they tend to have Young’s modulus of below 1
GPa.
The specific stiffness was set to between a minimum of 10 MN.m/kg to 30 MN.m/kg.
This will trigger the selection of materials that are not very stiff or very swift for the
application.
The tensile strength to h was set between 350 Mpa to 400 Mpa. While the Yield
strength was set to values of between 180 Mpa to 250 Mpa. The reasons for setting
the said values was to make sure weak materials are not selected and at the same
materials with very high or superficial strength or over engineered materials were
not selected.
The flexural modulus was set to a maximum of 150 GPa. I didn’t wasn’t to choose a
material with high flexibility as thy will deform very easily when turning the wheel
which might compromise on the handling and safety during operation. Again, this
was a major factor that eliminated many elastomers and thermoset plastic
materials as they tend to flex a lot.
The Poisons ratio was set to between 0.3 and 0.35. The properties such as shear
modulus and elongation can be derived from the specified Poisons ration with the
other properties such as the Young’s modulus, Tensile strength, and flexural
modulus.
The last property specified is the fatigue strength. The strength was set to 50 Mpa
minimum and maximum of 350 Mpa.

Figure 2. Selected mechanical properties.
The next property group was on the durability. The durability of the material for the
steering hub was set such that it was acceptable or excellent on fresh and salty
water.
The water craft is expected to be used outside in the sun where the parts are
subjected to UV radiations. This Durability rating of the material to degradation by
ultraviolet (UV) radiation from sunlight – the intrinsic durability in the absence of
additional protective measures. The material durability against degradation by the
sun need to be above good so good and excellent grades were selected.
Also, the bearing hub is a rotating par. It rotate with the steering wheel or handle.
As a result, the resistance of the material to galling, a type of adhesive wear
occurring between sliding surfaces that causes scratching and can lead to seizure
need to be high. Acceptable and excellent were checked. Excellent means that the
material is suitable for applications or mating with materials in which galling is a
major issue and will only gall in exceptional circumstances while acceptable means
that the material is suitable for applications which require galling resistance without
additional treatments, although have a tendency to gall in some circumstances.
The other boxes for the acids, alkalis, organic solvents, flammability, were left
unchecked.

Figure 3. Selected durability.
Having specified the price, mechanical and durability characteristics of the material,
the selection stage was applied and the results read. This gave a number of
possible materials indicated below.
a) Aluminum, 2017, T4
b) Aluminum, 2017, T42
c) Aluminum, 2017, T451
d) Aluminum, 2024, T3
e) Aluminum, 2024, T351
f) Aluminum, 2024, T3510/T3511
g) Aluminum, 2024, T4
h) Aluminum, 2024, T42
i) Aluminum, 2219, T62
j) Aluminum, 5182, H16
k) Aluminum, FC1-TF
l) Brass, CuZn39Pb2, C37700, soft (leaded (forging) brass)
m) Bronze, CuAl7, C61000, soft (93/7 aluminum bronze)
n) Bronze, CuNi15Zn21, C75400, soft (15% nickel silver)
o) Bronze, CuNi18Zn20, C75200, soft (18% nickel silver)
p) Bronze, CuNi18Zn29, C77000, soft (18% nickel silver)
q) Copper, C10100, hard (electrolytic tough-pitch h.c. copper)
r) Copper, C10200, hard (oxygen-free h.c. copper)
s) Copper, C10500, hard (silver-bearing oxygen-free h.c. copper)
t) Copper, C12200, hard (phosphorus de-oxidized arsenical h.c. copper)
u) Copper, C12500, hard (fire-refined tough-pitch h.c. copper)
v) Copper, C14200, hard (phosphorus de-oxidized arsenical h.c. copper)
w) Copper, C14200, hard (tough-pitch arsenical h.c. copper)
x) Copper-chromium alloy, C18200, wh (h.c. copper)
y) Copper-Cr-Zr alloy, C18100, wp (h.c. copper)
z) Copper-nickel alloy, C72650, soft (87.5/7.5 copper-nickel)
aa)Copper-sulfurous alloy, C14700, hard (h.c. copper)

bb) Copper-tellurium alloy, C14500, hard (h.c. copper)
Figure 4. materials passed all steges.
When sorted according to the Yield strength, the qualified materials were slightly
above the middle of the chart. Very strong materials such as tungsten carbide,
basalt, phynox- cold worked and tungsten tool carbide were eliminated. On the
other hand, very weak materials in Yield such as glass, aramid paper and foam were
eliminated.
Yield strength (elastic limit) (MPa)
0.01
0.1
1
10
100
1000
Cobalt-base-superalloy, Elgiloy/Phynox, cold worked, aged
Epoxy/HS carbon fiber, UD prepreg, QI lay-up
Copper, C14200, hard (tough-pitch arsenical h.c. copper)
Copper-chromium alloy, C18200, wh (h.c. copper)
Copper, C10100, hard (electrolytic tough-pitch h.c. copper)
Brass, CuZn36Pb3, C36000, (cold worked), (free-cutting brass)
Bronze, CuNi15Zn21, C75400, soft (15% nickel silver)
Copper-nickel alloy, C72650, soft (87.5/7.5 copper-nickel)
Polymethacrylimide foam (rigid, 0.051)
Aramid paper/phenolic honeycomb (0.072), W Direction
Aramid paper/phenolic honeycomb (0.029), W Direction
Epichlorohydrin copolymer (ECO/GECO, unreinforced)
Basalt (f)
Tungsten carbide-cobalt (93.04)
Tool steel, tungsten alloy, AISI T15 (high speed)
Al-47%SiC(f), 0/90/0/90
Aluminum, 2024, T81
Glass/phenolic honeycomb, 0°/90° fabric (0.112), L Direction
Figure 5. Chart for yield strength.

RANKING AGAINIST PRIMARY OBJECTIVES
It can be noted that there were 18 material that passed the initial screening
process. For this application, material properties depicting strength are high yield
strength ,high specific stiffness, High fracture toughness,, Low price, Acceptable to
excellent durability with fresh and salty water and low density Low density. To
construct a functional material index, I used the following values to represent the
durability. T.E.
DURABILITY IN FRESH
WATER
INDEX
VALUE
unacceptable 1
Limited use 2
acceptable 3
excellent 4
DURABILITY IN SALTY
WATER
INDEX
VALUE
unacceptable 1
Limited use 2
acceptable 3
excellent 4
DURABILITY IN UV
RADIATION
INDEX
VALUE
Poor 1
Fair 2
Good 3
Excellent 4
GALLING RESISTANCE
(ADHESIVE WEAR)
INDEX
VALUE
unacceptable 1
Limited use 2
acceptable 3
excellent 4
For this part, the desired properties are high Yield stress, high, high fracture
toughness, and high durability while the unwanted traits were high costs and high
density. Some of the mechanical properties were omitted in the formula since they
can be derived from the other mechanical properties. For instance, when assuming
that the tensile strength is 25% more than the Yield strength, the tensile strength
can be calculated.
M 1= Y × F × D
C × ρ
Where Y is the Yield strength, F is the Fracture toughness, D is the durability, C is
the cost per KG, is the density of the material. These values were the average
between the minimum and the maximum values. The durability D, was as a result of
summing up the material’s durability in fresh water, salty water, UV radiation and
adhesive wear.
For each material, the material index was as follows;
a) Aluminum, 2017, T4
M 1= Y × F × D
C × ρ = 232.5 ×32× 13
2.175 ×2795 =15.9108
b) Aluminum, 2017, T42
M 2= Y × F × D
C × ρ = 232.5 ×32 ×13
2.175 ×2795 =15.9108
c) Aluminum, 2017, T451

M 3= Y × F × D
C × ρ = 232.5 ×32 ×13
2.175 ×2795 =15.9108
d) Aluminum, 2017, T42
M 4 =Y × F × D
C × ρ =310 × 39× 13
2.185× 2765 =26.0150
e) Aluminum, 2024, T351
M 5= Y × F × D
C × ρ = 296.5 ×36.7 ×13
2.185 ×2765 =23.4146
f) Aluminum, 2024, T3510/T3511
M 6= Y × F × D
C × ρ = 232.5 × 41.75× 13
2.185 ×2770 =20.6628
g) Aluminum, 2024, T4
M 7= Y × F × D
C × ρ = 289 ×39 ×13
2.185 ×2770 =24.2089
h) Aluminum, 2024, T42
M 8= Y × F × D
C × ρ = 231 ×39 ×13
2.185 ×2765 =19.3853
i) Aluminum, 2219, T62
M 9= Y × F × D
C × ρ = 261 ×32.95 ×13
2.33 ×2855 =16.8065
j) Aluminum, 5182, H16
M 10= Y × F × D
C × ρ = 251.5× 33 ×13
2.03 ×2660 =19.9810
k) Aluminum, FC1-TF
M 11=Y × F × D
C × ρ = 255× 32.5× 13
2.265× 2830 =16.8079
l) Bronze, CuAl7, C61000, soft (93/7 aluminum bronze)
M 12=Y × F × D
C × ρ = 175× 59.45× 16
5.415× 7800 =3.9411
m) Brass, CuZn39Pb2, C37700, soft (leaded (forging) brass)
M 13=Y × F × D
C × ρ = 155× 62.75 ×16
5.81× 8635 =3.1019
n) Bronze, CuNi15Zn21, C75400, soft (15% nickel silver)
M 14= Y × F × D
C × ρ = 175 ×58.6 ×16
6.02 ×8635 =3.1564
o) Bronze, CuNi18Zn20, C75200, soft (18% nickel silver)
M15=Y × F × D
C × ρ = 175× 58.6 ×16
5.75 ×8705 =3.2781
p) Bronze, CuNi18Zn29, C77000, soft (18% nickel silver)