Analysis of Mechanical Properties for Various Materials

Belt, chain, and rope drives are fundamental components used to transmit power between machinery parts in numerous industrial settings. Each type of drive has unique characteristics that make them suitable for specific applications. Belt drives offer smooth operation with minimal maintenance but require precise tensioning to avoid slippage. Chain drives provide high torque transmission capabilities with robustness against heavy loads, though they can introduce noise and require lubrication. Rope drives are often employed in material handling and conveyance systems due to their flexibility and durability over long distances. This report delves into the principles governing these drive mechanisms, including force analysis, efficiency calculations, and fatigue considerations. By comparing these systems, we evaluate which configurations optimize performance for different mechanical engineering applications, ultimately guiding engineers in selecting appropriate drives based on operational requirements.

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MECHANICAL ENGINEERING: Rotary Shaft
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Abstract
The primary objective of this study is to discover some of the various variables that influence the
quality of material used in the construction of a rotary shaft. The research seeks to provide
answers to questions like “What physical and chemical properties should a material portray to be
considered best in the construction of a rotary shaft?” The target is to analyze the particular
feature of a material that suits its use in a rotary shaft.
The three commonly used materials in shafts are stainless steel, carbon steel, and
aluminum alloy. The three materials are compared based on their various properties, and the
most suitable one is chosen for use in the drive shaft. Commonly cold drawn low carbon steel is
used for the design of shafts. But when higher strength is desired an alloy of steel like nickel is
used (Alokesh and Animesh, 2015). In this particular model, steel would be the most suitable
material for use due to its high strength and the top speed of the shaft. Steel has some very
desirable properties that make it ideal for use in many mechanical designs.
Literature Review
Strength
Strength is the materials ability to resist changes due to externally applied force. Steel, in
particular, has a high tensile strength that makes it suitable for shaft design (Rene and Turcotte,
2010). The strength it possesses prevents it from quickly breaking when the force applied to it is
enormous. The tensile strength of steel ranges between 560MPa and 760MPa depending on the
grade used (Pelleg, 2012). The yield strength also varies between 320MPa and 390MPa. Those
properties imply that the force will need to be extremely high to break the shaft and thus the
forces that have been applied to our reference shaft can still be considered safe.

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Stiffness
Stiffness is the material’s ability to resist deformation when it is subjected to stress. It is
reliant on the modulus of elasticity or Young’s modulus as others may choose to call it. Steels
modulus of elasticity is 29 million PSI which is three times bigger than that for aluminum
making it suitable for the application (Nastasi et al., 2012).
Machinability
Machinability refers to the ease with which a material can be cut to suit different
purposes. Steel has some carbon content that improves its machinability (Gilmore, 2014). Steel
exhibits the best machinability, and this is due to the presence of carbon in steel, and thus it
requires little use of power to cut and obtain a perfect finish (Marikani, 2017).Face tuning
method can be used to test for machinability where cylindrical steel specimens are used as the
test piece and a triangular P-30 inserted into it to be used as a cutting tool.
Notch Sensitivity Factor
Notch sensitivity factor is the measure of the sensitivity of the material to changes in
geometric discontinuities. Notch geometry is said to have very intense effects on the material’s
fatigue life (Dahai and Haer, 2016). Steel has low notch sensitivity factor and is therefore suited
for use in shafts.
Wear Resistance
Wear resistance is a property of a material that helps to withstand abrasion especially
between moving parts (Shetty, 2015). Materials used in the construction of shafts should have
high wear resistance property to prolong life. Steel, in particular, has a very high wear resistance

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property making its use in shafts useful. Wear resistance is measured using The Amsler machine
(Sha, 2013).
Heat Treatment
Heat treatment is the application of very high temperatures to a material to modify the
physical and mechanical properties of that particular material without having to alter its shape.
Steel, in particular, can undergo heat treatment to yield various microstructures and properties
both physical and chemical (Askeland et al., 2011). Steel has an excellent heat treatment
property that makes it a very suitable material for rotating shafts.
Dimensions of the shaft
We assume safe values for stress
P=3kW, speed=1500rpm, F1= 2kN, F2=1kN
First, calculate the torque transmitted by the shaft
T=(P×60)/2πN=(3×1000×60)/(2π×1500)
T=19.0986 N-m
From the figure, maximum bending occurs at point A
Therefore the maximum bending moment M= 2000×0.8
Thus M=1600N-m
Equivalent twisting moment Te=√(M^2 )+T²
Te=√1600²+19.0986²

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=1600.11N-m which is equivalent to (1600.11×1000) N-mm
Also Te=π/16× τ×d^3 (assuming τ=60N/mm2) (Prakash and Suresh, 2011)
Implying that 1600.11×1000=11.7809d3
d3=135812.2181 therefore
Diameter=51.40mm
Diagram of Bending Moment
Diagram of Shear Force

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Torque Diagram
(Jianli et al.,
2017)
Causes of Material Failure
Fatigue
Fatigue is caused by the number of stress cycles that the shaft experiences. Corrosion of
the material also lowers the fatigue strength of the material thus causing failure. Once the fatigue
strength has hugely reduced the material starts developing cracks that extend perpendicularly
forming lines of weaknesses that lead to breakage (Christensen, 2013).
Overload
Overload failures are as a result of forces that are greater than the yield strength of
material. This type of failure is further dependent on the material’s ductility ore brittleness
(Holm and Sadowski, 2014). Shaft materials are not always entirely brittle or ductile, and
therefore when extremely high loads are placed on the shafts, they twist and falsify causing
failure.
Plane bending

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Gravity or inertia loads cause plane bending. Plane bending causes fatigue in the material
and thus setting up stresses as a result of torque and turning moments (Barber, 2010). Lines of
weakness are therefore created in inform of cracks that run perpendicular causing breakage.
Torsional fatigue failures
Torsional fatigue failures are as a result of reversed torsional stresses. Torsional fatigue
failures lead to alteration of the fracture plane from 90 degrees to 45 degrees to the shaft axis that
is normal to the maximum tensile plane that results from the tear due to torsion (Jay and
Samantha, 2014).
Task 2
Abstract
A pulley is a simple machine that supports a change of direction of a taut cable with a wheel and
a shaft. It is instrumental in lifting or lowering weights to great heights or depths respectively.
They offer a mechanical advantage over other simple machines enabling the user to apply a large
force (Bird, 2013). It is made up of blocks and belts that run around the blocks allowing energy
transfer from the point of application of the effort to the load. The belt drive offers a smooth
transfer of power between two or more shafts separated by considerable distances. Belt drive
materials should be durable, flexible and reliable. Some of the most suitable materials used for
the belt in our task include; leather, rubber, and plastic.
Literature Review
Leather Belt

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The leather is commonly used in the construction of flat belts and is retrieved from the
steer or either side of the backbone (Experts, 2017). They are powerful and exhibit high tensile
strength. Leather strips are usually bound together thus increasing their thickness (Seeler, 2014).
Taking the dimensions of the pulleys into consideration the required length of the belt would be
1328mm. In the case of an open belt drive the dimensions will be calculated as follows;
2L + D1 + D2 = (2×450) + 180 + 90=1170mm
Rubber Belts
Rubber belts are manufactured by combining fabric with rubber, and they always have a
thin rubber layer the belt surface. They are usually very flexible and can be made endless with
ease (Hocken and Pereira, 2016). The major problem with these rubber belts though is that they
are easily damaged when they come into contact with grease or oil or if subjected to high
temperatures. In most cases, they are used in moist areas such as in paper mills (Jindal, 2010).
Since rubber is elastic, it does not snap easily unless the applied force exceeds the elastic limit.
The length of belt required to suit the task in question is 1328mm, and for the case of an open
belt, the length will be similar to that of a leather belt. Therefore length of the belt will be;
2L + D1 + D2 = (2×450) + 180 + 90=1170mm
Plastic Belts
Plastic belts comprise of plastic sheets combined with rubber layers. They resist abrasion
and also resists any effects that may come as a result of oil or moisture. It holds an advantage
over the other materials since it can be designed into almost every width (Goyal, 2011). The
dimension of the plastic required to manufacture a plastic belt for the above particular task is

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1328mm while the length of an open belt that would be required would be similar to the lengths
of the other two types of belts as calculated above. Therefore the length of belt required will be;
2L + D1 + D2 = (2×450) + 180 + 90=1170mm
Type of Bearing
Abstract
A bearing is an element of a machine that has relative motion in a specified direction. It is
instrumental in moving parts since it reduces friction. The design of a bearing may offer free
movement of the moving parts in a straight line or rotation around an axis (Bhandari, 2010). It is
also capable of preventing the motion by regulating the vectors of the normal forces that exist
around the moving parts. Bearings are therefore categorized based on the type of operation, the
movement that it allows, or the directions of the applied forces. The several kinds of bearing are;
ball bearings, roller bearings, ball thrust bearings, roller thrust bearings as well as tapered roller
thrust bearings (Schmid et al., 2014). The most convenient type of bearing in the above task
would be a roller bearing.
Literature Review
Roller Bearing
Roller bearings are convenient in conveyor belts where they support large radial loads. In
this type of bearing, the roller is made using a cylinder thus forming a line contact between the
inner and the outer race (Tong, 2014). This configuration spreads out the load over a wider area
thus enabling the bearing to withstand more significant loads in comparison to ball bearings.
Based on the specifications of the belt drive the bearing should have the following specifications.

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 Bore diameter = 200mm
 Width =360mm
 Fillet radius =4mm
 Inner ring diameter =244mm
 Shoulder height =258mm
 Poisson’s ratio =0.291
 Young’s modulus = 200 E-9
Fitting Type
The fit is the magnitude of tightness between the bore and the external diameter of the
bearing. Fitting types are categorized into interference fits, clearance fits, and transition fits. Fits
ensure that bearings do not have slips by strongly attaching the inner ring to the shaft and
housing (Plantenberg, 2016). The most appropriate fitting type would be an interference fit.
The interference fit is created through thermal expansion. The part to be inserted is
subjected to cooling, and as a result, it contracts after which it is embedded in the larger piece. It
is the tightest type of fitting and therefore the most efficient of fits (da Silva et al., 2011).
Interference fits are suitable for parts of a machine that which can be subjected to high stresses
and joining of components can be done by application of cold pressing.
Interference fits can be grouped into three, that is the locational interference fit, medium
drive fit, and force fit. Location interference fit is used for parts that demand rigidity and
orientation with a maximum accuracy of the location (Fu, 2016). Medium drive fits are used for
ordinary pieces of steel and shrink fits located on light sections. Force fits, on the other hand, are
used in parts of the machine which are subjected to high stresses or where massive pressing

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forces required are not practical like in the case of shrink fits (Heinz and Geitner, 2012). Shaft
Tolerance
Inner ring
(Helmi et al., 2011)

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Outer Bearing