backhoe loader finite element analysis

MSRSAS - Postgraduate Engineering and Management Programme - PEMP

Machinery design -1

i

ASSIGNMENT

Module Code MMD513

Module Name Machinery design - 1

Course M.Sc [Engg] in Machinery design

Department Mechanical & Manufacturing Engineering.

Name of the Student Prabhakar.P

Reg. No BAB0911001

Batch Full-Time 2011.

Module Leader Asst.Prof.Balappa.B.U

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M.S.Ramaiah School of Advanced Studies

Postgraduate Engineering and Management Programmes(PEMP)

#470-P Peenya Industrial Area, 4th Phase, Peenya, Bengaluru-560 058

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Declaration Sheet

Student Name Prabhakar.P

Reg. No BAB0911001

Course Machinery design Batch Full-Time 2011.

Batch FT-11

Module Code MMD513

Module Title Machinery design -1

Module Date 09/07/2012 to 04/08/2012

Module Leader Asst. Prof. Balappa.B.U

Extension requests:

Extensions can only be granted by the Head of the Department in consultation with the module leader.

Extensions granted by any other person will not be accepted and hence the assignment will incur a penalty.

Extensions MUST be requested by using the ‘Extension Request Form’, which is available with the ARO.

A copy of the extension approval must be attached to the assignment submitted.

Penalty for late submission

Unless you have submitted proof of mitigating circumstances or have been granted an extension, the

penalties for a late submission of an assignment shall be as follows:

• Up to one week late: Penalty of 5 marks

• One-Two weeks late: Penalty of 10 marks

• More than Two weeks late: Fail - 0% recorded (F)

All late assignments: must be submitted to Academic Records Office (ARO). It is your responsibility to

ensure that the receipt of a late assignment is recorded in the ARO. If an extension was agreed, the

authorization should be submitted to ARO during the submission of assignment.

To ensure assignment reports are written concisely, the length should be restricted to a limit indicated in

the assignment problem statement. Assignment reports greater than this length may incur a penalty of

one grade (5 marks). Each delegate is required to retain a copy of the assignment report.

Declaration

The assignment submitted herewith is a result of my own investigations and that I have conformed to the

guidelines against plagiarism as laid out in the PEMP Student Handbook. All sections of the text and results,

which have been obtained from other sources, are fully referenced. I understand that cheating and plagiarism

constitute a breach of University regulations and will be dealt with accordingly.

Signature of the student Date

Submission date stamp (by ARO)

Signature of the Module Leader and date Signature of Head of the Department and date


Machinery design -1

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Abstract

____________________________________________________________________________

In presents days the manufacturing in the industries are changed, in order to competite

in market the manufacturing methods are changed as per the customer requirements. For which

all most all the industries deviated from the standard machines and started using special

purpose machines and CNC machines and even in the construction and agricultural field the

various machineries are developed in order to reduce the human effort. The module machinery

design-1 covers the idea of building up the mechanism by considering the various output

requirements of the machine using the standard machine elements like gears, pulleys, shafts etc

with design calculations.

In this assignment Part-A debate is on design consideration by mechanical designer

while designing the mechanical structures, were under four sub topics showing the various

design consideration such mechanical strength, optimization and aesthetic by analyzing the

given sub topic with the suitable case study the debate is presented.

In the Part-B the physical dimensions of backhoe is taken from the excavator and

modeled in CATIA v5 R16 software and the kinematic analysis is carried out using the

ADAMS software, in which the angular velocity and angular accelerations were found in the

pin joints of the backhoe. The basic calculations and comparison of the various link lengths

obtained from the calculation and actual link lengths are shown. The free body diagram of the

backhoe showing the forces acting at the various parts after lifting the mass 1m above the

ground level.

In the Part-C assignment FEA analysis is carried out were initially the model is meshed

using the Hyper mesh 2009 software by assigning the boundary conditions, material properties

and element types etc. the input from the hypermesh is taken to ANSYS 12.1 and the results of

displacement sum vector and vonmises stress is found the analysis is carried out with bucket

alone, boom and stick alone and whole backhoe assembly together. Then without

compromising the strength the shape modification is done to the stick and the boom part, the

modified parts were meshed using hypermesh and again the results were obtained from the

ANSYS and comparison of the results are shown.

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Contents

____________________________________________________________________________

Contents

Declaration Sheet .......................................................................................................................... ii

Abstract ........................................................................................................................................ iii

Contents ....................................................................................................................................... iv

List of Tables ............................................................................................................................... vi

List of Figures ............................................................................................................................. vii

List of Symbols ............................................................................................................................ ix

1.0 Introduction: ......................................................................................................................... 10

1.1 Mechanical strength, design optimization and aesthetic [1],[2] & [3]: ................................ 10

1.2 Mechanical strength and design optimization [4] & [5]: ...................................................... 11

1.3 Mechanical strength [6]: ....................................................................................................... 11

1.5 Conclusion: ........................................................................................................................... 12

2.0 Introduction: ......................................................................................................................... 13

2.1 Backhoe portion: .................................................................................................................. 13

2.1.1 Degrees of freedom of backhoe: ........................................................................................ 14

2.2 The materials used in backhoe: ............................................................................................ 14

2.3 Calculating bucket capacity calculation: .............................................................................. 15

2.3.1Calculating digging force calculation: ................................................................................ 16

2.3.2 Stick and arm length calculation: ...................................................................................... 17

2.3.3 Assumptions made in calculation: ..................................................................................... 17

2.3.4 Idealized cross section of stick: ......................................................................................... 18

2.3.5 Finding the length using bending equation: ...................................................................... 18

2.3.6 Idealized cross section of Boom: ....................................................................................... 19

2.3.7 Finding the length using bending equation: ...................................................................... 20

2.3.8 Finding the pin diameter using bending equation: ............................................................ 21

2.4 Free body diagram of Backhoe: ............................................................................................ 21

2.4.1 Kinematic analysis in ADAMS: ........................................................................................ 22

2.4.2 The reach diagram obtained in ADAMS: .......................................................................... 23

2.5 Range graph of backhoe: ...................................................................................................... 23


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2.6 Velocity and acceleration results of backhoe: ...................................................................... 24

2.6.1 Result of angular velocity graph at bucket hinge: ............................................................. 24

2.6.2 Result of angular acceleration graph at bucket hinge: ....................................................... 25

2.6.3 Result of angular velocity graph at stick hinge: ................................................................ 26

2.6.4 Result of angular acceleration graph at stick hinge: .......................................................... 26

2.6.5 Result of angular velocity graph at Boom hinge: .............................................................. 27

2.6.6 Result of angular acceleration graph at Boom hinge: ........................................................ 28

2.7 Modeling of Backhoe in CATIA: ......................................................................................... 29

3.0 Introduction: ......................................................................................................................... 31

3.1 Finite element model conversion: ......................................................................................... 31

3.1.1 Bucket: ............................................................................................................................... 32

3.1.2 Boom and stick: ................................................................................................................. 33

3.1.3 Backhoe assembly: ............................................................................................................ 33

3.2 Boundary conditions used for analysis: ................................................................................ 35

3.2.1 Boundary conditions and load analysis of bucket: ............................................................ 35

3.2.2 The Displacement of the bucket: ....................................................................................... 35

3.2.3 Vonmises stress in the bucket: ........................................................................................... 36

3.2.4 Boundary conditions and load analysis of Stick and boom: .............................................. 36

3.2.5 The Displacement of the boom and stick: ......................................................................... 37

3.2.6 Vonmises stress in the stick and boom: ............................................................................. 38

3.2.7 Boundary conditions and load analysis of backhoe assembly: .......................................... 39

3.2.8 The Displacement of the backhoe assembly: .................................................................... 39

3.2.9 Vonmises stress in the stick and boom: ............................................................................. 40

3.3 Improving the asthetic without compromising the strength: ................................................ 41

3.3.1 Modification in Boom: ...................................................................................................... 41

3.3.2 Modification in stick: ........................................................................................................ 42

3.4 Result validation after optimisation of structure: ................................................................. 43

3.4.1 Displacement result comparison: ....................................................................................... 43

3.4.2 Vonmises Stress result comparison: .................................................................................. 44

Learning outcomes: .................................................................................................................... 45

References .................................................................................................................................. 46


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Appendex-1 ................................................................................................................................ 47

[Elemental results of hyper mesh]

Appendex-2 ................................................................................................................................ 52

[Line diagram of Backhoe assembly]

List of Tables

____________________________________________________________________________

Table No. Title of the table Pg.No.

Table 1. 1 Drill bit parameters ............................................................................................... 10

Table 1. 2 Results of comparison of TiN & HSS dry drill performance ............................... 10

Table 2. 1 Showing materials used in Backhoe assembly ..................................................... 15

Table 3. 1 Element characteristics of Bucket ......................................................................... 32

Table 3. 2 Element characteristics of Boom and Stick ........................................................... 33

Table 3. 3 Element characteristics of Backhoe assembly ....................................................... 34


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List of Figures

____________________________________________________________________________

Figure No. Title of the figure Pg.No.

Fig 1. 1 FEA results for optimization ......................................................................................... 11

Fig 1. 2 Showing optimization on connecting rod ..................................................................... 11

Fig 1. 4 Duct lines for ventilation ............................................................................................... 12

Fig 1. 3A- Single crystal structure Fig1.3B-Ceramic coating .................................................... 12

Fig 2. 1 Excavator ...................................................................................................................... 13

Fig 2. 2 Backhoe parts ................................................................................................................ 13

Fig 2. 3 DOF of Backhoe ........................................................................................................... 14

Fig 2. 4 Bucket dimension .......................................................................................................... 15

Fig 2. 5 Parameters used in Backhoe calculation ....................................................................... 16

Fig 2. 6 showing stick dimensions ............................................................................................. 18

Fig 2. 7 showing details of stick cross section ........................................................................... 18

Fig 2. 8 Showing Boom dimensions .......................................................................................... 19

Fig 2. 9Showing details of Boom cross section ......................................................................... 20

Fig 2. 10 Free body diagram of Backhoe ................................................................................... 21

Fig 2. 11 Joints provided in ADAMS ......................................................................................... 22

Fig 2. 12 Reach diagram obtained in ADAMS .......................................................................... 23

Fig 2. 13 Graph showing Distance traveled by bucket ............................................................... 23

Fig 2. 14 Velocity graph at Bucket hinge ................................................................................... 24

Fig 2. 15 Angular acceleration graph at Bucket hinge ............................................................... 25

Fig 2. 16 Angular velocity at Stick hinge ................................................................................... 26

Fig 2. 17 Showing Angular acceleration at stick hinge .............................................................. 27

Fig 2. 18 Angular velocity at Boom hinge ................................................................................. 28

Fig 2. 19 Showing Angular acceleration at Boom hinge ............................................................ 29

Fig 2. 20 Boom & Bucket modeled in CATIA .......................................................................... 29

Fig 2. 21 Bucket link & Bucket quick attach link modeled in CATIA ...................................... 30

Fig 2. 22 Stick and Pivot bucket link modeled in CATIA ......................................................... 30


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Fig 2. 23 Backhoe assembly created in CATIA ......................................................................... 30

Fig 3. 1 Showing Solid45 element DOF .................................................................................... 31

Fig 3. 2 Showing Mass21 element DOF .................................................................................... 32

Fig 3. 3 Bucket meshed in HYPERMESH ................................................................................. 32

Fig 3. 4 Boom & Stick meshed in HYPERMESH ..................................................................... 33

Fig 3. 5 Showing assembly meshed in HYPERMESH .............................................................. 34

Fig 3. 7 Showing Displacement sum vector results of bucket ................................................... 35

Fig 3. 6 Loads and Boundary conditions on Bucket .................................................................. 35

Fig 3. 8Showing Vonmises stress results of bucket ................................................................... 36

Fig 3. 9 Boundary condition and loads on stick & Boom assembly .......................................... 37

Fig 3. 10 Displacement results of stick & Boom assembly ........................................................ 37

Fig 3. 11 Showing Vonmises stress result of stick & Boom assembly ...................................... 38

Fig 3. 12 Showing boundary condition on Backhoe assembly .................................................. 39

Fig 3. 13 Showing displacement results of Backhoe assembly .................................................. 40

Fig 3. 14 Showing Vonmises stress results of Backhoe assembly ............................................. 40

Fig 3. 16 Boom Modeled - Before modifying shape .................................................................. 41

Fig 3. 15 Idealisation of simply supported beam as Boom ........................................................ 41

Fig 3. 17 Boom Modeled - after modifying shape ..................................................................... 42

Fig 3. 19 Stick modeled before modification of shape ............................................................... 42

Fig 3. 18 Showing stress concentration at the sharp corner ....................................................... 42

Fig 3. 20 Stick modeled after modification of shape .................................................................. 43

Fig 3. 21 Displacement result comparison before and after optimization .................................. 43

Fig 3. 22 Vonmises stress result comparison before and after optimization .............................. 44


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List of Symbols

____________________________________________________________________________

Symbol Description Units

F Force N

ɽ Torque N-m

K

m

d

l

f

a ө

Bulk modulus

Mass

Diameter

Length

Frequency

Angular velocity

Angle

N/m2

kg

m

m

Hz

m/s

deg

g Acceleration due to gravity - 9.81 m/s2

ω

σ

P

A

E

S

M

I

Angular acceleration

Stress

Pressure

Area

Young’s modulus

Factor of safety

Bending moment

Moment of inertia

m/s2

N/m2

N/m2

m2

N/m2

N-mm

N-mm

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PART-A

CHAPTER 1

1.0 Introduction: The mechanical designer uses the engineering tools (such as mathematics, statistics,

computers, graphics, and languages) etc, to formulate the plan or design for finding the solution for

specific problem. While designing mechanical structures the various aspects are required to

considered by the designer, such as functionality of the structure, safety of structure, reliable,

competitors in market, usable, manufacturable and marketable. In this debate by considering the

four various aspects under different subtitles the debate has to be answered by supporting with case

study by selecting a mechanical component under above mentioned aspects.

1.1 Mechanical strength, design optimization and aesthetic [1],[2] & [3]: The component were the mechanical strength, design optimization and aesthetic are

considered in the mechanical structure is titanium nitrate (TiN) coated drill bit. Usually drill bits

made of HSS (high speed steel) material, it is used to perform drilling operation. Were the HSS

material is selected as cutting tool material by considering the strength, which has red hardness

property were the material will not loose its hardness at the

elevated temperature, the material has the hardness of 67HRC

this property can be considered under strength[1]. For design

optimization and aesthetic purpose the HSS material is coated

with titanium nitrate material by physical vapor deposition

processes. In the test conducted by Kadam M.S [2] the results

are shown in Table1.1. Were the results shows TiN drill with parameters shown in Table1.2

operates at high torque and less chip load for the same diameter, type, feed and rpm used for HSS

drill without TiN coating which in turn TiN coated drill reduces the cycle time thus functional

optimation is carried out in HSS drill bit by TiN coating. The TiN covers the ascetics part by “TiN

is used to harden and protect cutting and sliding surfaces, for decorative purposes (due to its gold

appearance)”[3] according to Wikipedia.

Table 1. 1 Drill bit parameters

Table 1. 2 Results of comparison of TiN & HSS dry drill performance


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1.2 Mechanical strength and design optimization [4] & [5]: The mechanical strength and design optimization alone is consideration the connecting rod,

which connects piston to the crank shaft and

transmits the power from piston to crankshaft.

The connecting rod undergoes high loads, It

undergoes high cyclic loads of the order of 108 to

109 cycles [4], which range from high

compressive loads due to combustion, to high

tensile loads due to inertia therefore the

connecting rod is designed considering the fatigue

strength. The design optimization is done for

connecting rod in order to reduce the weight and

reduce the manufacturing cost Alex Antoc

MAHLE Industries Inc[5], conducted an experiment on design of light weight connecting rod in

which by using FEA analysis is shown in Fig1.2 were red area is non-stressed and black area is

stressed portion. He found possible modification in design and carried out the weight optimization

is done and the results are plotted in graph as shown in Fig1.1. The aesthetic will not be considered

in this structure as it is enclosed within the cylinder housing.

Fig 1. 2 FEA results for optimization

1.3 Mechanical strength [6]: The strength alone is considered for structure of turbine blades, The blades are responsible

for extracting energy from the high temperature, high pressure gas produced by the combustor. As

the jet turbine blades are exposed to very high temperature about 1350ᵒC. According to Harry

Fig 1. 1 Showing optimization on connecting rod


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Bhangu[6] “Specified life of stage 1 turbine blade is +50,000 hours ≈ 6 years, for six years the

blade has to rotate continuously at 3000 RPM in a very harsh environment” in order to obtain the

life in the turbine blades only the strength is considered were the optimization and aesthetic is

totally neglected. In order to avoid the creep failure in blade the blade is made of super alloy with

single crystal structure as shown in Fig1.3A. In order to withstand the temperature ceramic coating

is done as shown in Fig1.3B.

1.4 Aesthetic [7]:

The aesthetic alone is considered in the structures like duct work which is used for ventilation

purpose, were when the pipe lines are exposed outside the aesthetic becomes the important part of

the structure. The case study, Cox, Kliewer & Company,[7] a Virginia-based architectural firm,

while relocating their working place they introduced innovative design of duct which proves the

modern look and cool and pure air throughout the building as shown in the Fig1.4. These duct lines

are usually of polymeric plastic material and the cut section is shown in the below Fig which results

in aesthetic alone were strength and optimization is neglected.

Fig 1. 4 Duct lines for ventilation

1.5 Conclusion:

The mechanical designer should keep in mind the design is the combination of various aspects like

strength, optimization and aesthetic these requirements a changes with the application of the

structure therefore it is essential to study the structure thoroughly before designing.

Fig 1. 3A- Single crystal structure Fig1.3B-Ceramic coating


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PART-B

CHAPTER 2 ________________________________________________________________________________ 2.0 Introduction:

Backhoe loader is the power driven mechanism used for digging, moving or transporting of

the loose gravel, sand or soil. It is general purpose construction equipment which is the combination

of i) A Tractor ii) A loader and iii) A back hoe. The core structure of the backhoe loader is built on

the tractor; the loader is fixed in the front portion were it is used to carry the loose material and the

backhoe is fixed in the back portion of the backhoe loader. The backhoe is the main tool of the

backhoe loader. It's used to dig up hard, compact material, usually earth, or to lift heavy loads.

The Backhoe portion has 3 segments:

• The boom

• The stick and

• The bucket

2.1 Backhoe portion:

In this assignment the backhoe portion has to analysed the backhoe

portion and based on the function the backhoe portion comes under the

first class lever in which the fulcrum is placed between the load and effort

as shown in the Fig2.2. The part of the backhoe holding the bucket is

called the stick and the stick is attached to another part of the backhoe

called the boom. When the hydraulic piston attached to the boom pulls the

stick, the stick pivots on its fulcrum, which is where it is attached to the

boom. This causes the other end of the stick to lift and so the mechanism is

classified under the first class lever.

Fig 2. 1 Excavator

Fig 2. 2 Backhoe parts


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2.1.1 Degrees of freedom of backhoe:

The DOF comparison between the human arm

and the backhoe is shown in the Fig2.3. As the

backhoe functions similar to human arm, but

DOF in the backhoe mechanism is less than

human arm as the human arm has 8 DOF while

the backhoe has 4 DOF.

The various joints and pairs used in the

backhoe mechanism to obtain these DOF

are:

• Revolute joints – has one DOF able to rotate about its axis (lower pair as a journal bearing

with a pin is used to obtain the DOF)

• Prismatic joints – has one DOF able to translate about its axis (lower pair as a hydraulic

cylinder with piston is used to obtain the DOF)

In the backhoe mechanism there are 12 links which are:

i) Ground – the link fixed to the tractor. ii) Boom – the 2nd link.iii) Hydraulic cylinder – as 3

cylinders are used can be considered as 3 more links iv) Pistons – can be considered as 3 more links

v) Stick – 9th link vi) two links connected to bucket and stick vii) Bucket – 12th link.

As 3 hydraulic cylinders are used and therefore 3 prismatic pairs are there and the rest are revolute

pairs. If the 3 hydraulic cylinders are actuated the (output link) bucket is controlled in planar

motion. Were the (output link) bucket can possibly have 2 translation motion and 1 rotational

motion in the plane and the other DOF for the (output link) bucket is rotational a swing motion

provided to the boom which in turn provide the motion to bucket to change its plane.

2.2 The materials used in backhoe:

The materials used in the construction of the backhoe are:

Si.no Part description Material used

01 Boom Medium strength alloy steel casted

to the shape

02 Stick Medium strength alloy steel casted

to the shape

Fig 2. 3 DOF of Backhoe


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03 Hydraulic cylinder Seamless steel tubes are rolled and

formed

04 Hydraulic cylinder piston Stainless steel with chrome plated

05 Seals Elastomeric plastic (to with stand

high temperature)

06 Buckets Ductile cast iron

07 Plain bearing Babbit, bi-metal

08 Hinge pin Hardened carbon steel

Table 2. 1 Showing materials used in Backhoe assembly

2.3 Calculating bucket capacity calculation:

Bucket capacity is a measure of the maximum volume of the material that can be

accommodated inside the bucket of the backhoe excavator. In the Fig() the dimensions of the

bucket of which bucket capacity is to be calculated is shown.

Fig 2. 4 Bucket dimension

The bucket capacity can be calculated by:

VBC = VDC +VEC

Were, VBC = Bucket capacity, VDC = Dump capacity and VEC = Excess capacity

The dump capacity (VDC) can be calculated by:


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Were, = area of inner surface of bucket, Wr = inside width of the bucket and Wf = Outer

width of bucket.

The excesses capacity (VEC) can be calculated by:

� ��

Therefore the bucket capacity (VBC) =

2.3.1Calculating digging force calculation:

As the analysis is carried out in planar were only the 3 DOF of the bucket digging force is

calculated by finding the curling force of the bucket (FB) and the mass force of the bucket (FS) as

shown below:

Fig 2. 5 Parameters used in Backhoe calculation

The curling forces are calculated by using the formula:


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π�

Were, FB = curling force of bucket, the other terms dA, dB, dC, and dD, shows the distances as

shown in Fig().

The mass force is calculated using the formula:

π�

Were, FS = Mass force on arm, the other terms DA, dE, and dF, shows the distances as shown in

Fig().

By using these formulas the bucket curl or breakout force is calculated as 8000N and the arm mass

force or digging force is calculated as 4500N. the maximum lifting capacity of bucket is calculated

as 2000N.

2.3.2 Stick and arm length calculation:

The yield strength of carbon steel (ASTM - A 514) = 690 N/mm2.

Factor of safety = 5[8]

According to Roymech, UK standards [8]“The FOS =5,Should also be used with better-known

materials that are to be used in uncertain environments or subject to uncertain stresses”. As the

backhoe experiences uncertain stresses by the angle of digging suppose if the bucket angle is

around 45o the digging force experienced by the bucket will be less similarly if the bucket angle

moves away from 45o the force required will be more it depends on the skill of the operator.

Therefore allowable yield strength = 690/5 = 138 N/mm2.

2.3.3 Assumptions made in calculation:

• The boom cross section is idealized to channel section.

• The stick cross section is idealized to box cross section.

• The maximum bending stress does not exceed the allowable yield strength 138 N/mm2

value.

• Thus in bending equation instead of the bending stress the allowable yield strength value is

substituted.


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2.3.4 Idealized cross section of stick:

The shape of the stick is shown in Fig2.6. Were the dimensions of boom, the length and the cross

section are shown for idealization of cross section and to find the length.

Fig 2. 6 showing stick dimensions

The cross section of the boom is idealized to the rectangular tubular section which has the

breadth of 102 mm and depth of 127 mm and the wall thickness is idealized as 6.5 mm. the details

of the values of the cross section such as area, moment of inertia etc, are shown in the Fig2.7 below.

Fig 2. 7 showing details of stick cross section

2.3.5 Finding the length using bending equation:

σ

Were, M = bending moment in N-mm, I = moment of inertia inmm4, σ = bending stress in N/mm2

and y = distance from neutral axis to the outer surface in mm.


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In the bending equation instead of the bending stress the allowable yield strength value is

substituted as per the assumption made as the maximum bending stress will be allowed to reach the

value of 138 N/mm2.

M = 13908661.42 N-mm.

Moment = force X distance

Were, the force is taken as the bucket curl or breaking force as calculated which is 8000N.

Therefore the link length is:

Stick length = Moment / Breaking force

= 13908661.42 / 8000

= 1738.58mm

2.3.6 Idealized cross section of Boom:

The shape of the boom is shown in Fig2.8. Were the dimensions of boom, the length and the cross

section are shown for idealization of cross section and to find the length.

Fig 2. 8 Showing Boom dimensions

The cross section of the boom is idealized to the channel section which has the breadth of

113 mm and depth of 152 mm and the wall thickness is idealized as 6.5 mm. the details of the

values of the cross section such as area, moment of inertia etc, are shown in the Fig2.9 below.


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Fig 2. 9Showing details of Boom cross section

2.3.7 Finding the length using bending equation:

σ





value of 138 N/mm2.

M = 16759736.84 N-mm.

Moment = force X distance

Were, the force is taken as the bucket curl or breaking force as calculated which is 8000N.

Therefore the link length is:

Stick length = Moment / Breaking force

= 16759736.84 / 8000

= 2094.96mm.


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2.3.8 Finding the pin diameter using bending equation:

σ



The yield strength of carbon steel (ASTM - A 514) = 690 N/mm2.

Factor of safety = 2.5[8]

According to Roymech, UK standards [8]“The FOS =2.5 Materials obtained for reputable

suppliers to relevant standards operated in normal environments and subjected to loads and

stresses that can be determined using checked calculations”

Therefore allowable yield strength = 690/2.5 = 276 N/mm2.



value of 230 N/mm2.

.

2.4 Free body diagram of Backhoe:

Fig 2. 10 Free body diagram of Backhoe


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The backhoe while lifting the mass 1m above ground level the stick portion is subjected to the

various forces shown below:

• Resultant force from pin “D”

• Resultant force from pin “F”

• Force, FBE

• Force, FHI

• Force, FBC

The backhoe while lifting the mass 1m above ground level the Bucket portion is subjected to the


• Mass “W”

• Resultant force from pin “D”

• Force, FBA

The backhoe while lifting the mass 1m above ground level the Boom portion is subjected to the


• Resultant force from pin “H”

• Resultant force from pin “F”

• Force, FHI

2.4.1 Kinematic analysis in ADAMS: The dimensions of the backhoe is collected from the JCB and using the modeling software

CATIA R16 the parts are modeled as per the dimensions obtained which is scale down to the ratio

of 1:2 and the assembly is converted into parasoild to import in ADAMS software for kinematic

analysis. The various joints provided in the ADAMS is shown in the Fig2.11.

Fig 2. 11 Joints provided in ADAMS


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2.4.2 The reach diagram obtained in ADAMS:

Fig 2. 12 Reach diagram obtained in ADAMS

2.5 Range graph of backhoe:

Fig 2. 13 Graph showing Distance traveled by bucket

For the backhoe mechanism the trace spline is plotted along the path taken by the bucket in

ADAMS which in turn provide the detail of the range covered by the backhoe as shown in the

Fig2.12.


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Result interpretation:

The range graph shown in the Fig2.13 has time in second in horizontal axis and length in

mm in vertical axis as by using the step function in ADAMS, the motion is given to hydraulic

cylinders connected to stick, boom and bucket of backhoe and the graph is plotted from which the

result interrupted for the scale down model as the modeling is done to the scale of 1:2 from the

graph can be observed that the maximum distance covered by backhoe is 961.00mm for the scale

down model.

2.6 Velocity and acceleration results of backhoe:

The angular velocity and angular acceleration results are mapped on the graph using ADAMS

software at the various pin joints connecting the links. The results at the following joints are shown:

i) Ground and boom.

ii) Boom and stick.

iii) Stick and bucket.

2.6.1 Result of angular velocity graph at bucket hinge:

Fig 2. 14 Velocity graph at Bucket hinge


The angular velocity graph at bucket hinge is shown in the Fig2.14 has time in second in

horizontal axis and angular velocity in degree/second in vertical axis as by using the step function

in ADAMS the motion is given to hydraulic cylinder connected to bucket the graph is plotted. From


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the graph for the scale down model (1:2) the result obtained is the maximum velocity is 7.094deg/s.

In which the for the first 6second the velocity increases from zero to maximum and then in next 4

second the velocity decreases from maximum to zero.

2.6.2 Result of angular acceleration graph at bucket hinge:

Fig 2. 15 Angular acceleration graph at Bucket hinge


The angular acceleration graph at bucket hinge is shown in the Fig2.15 has time in second in

horizontal axis and angular acceleration in degree/second2 in vertical axis as by using the step

function in ADAMS the motion is given to hydraulic cylinder connected to bucket the graph is

plotted. From the graph for the scale down model (1:2) the result obtained is the maximum angular

acceleration is 3.746deg/s2. In which the angular velocity is 2.61 deg/s2 is observed at the beginning

the transition from zero to 2.616deg/s2 takes in short time and as at the 6th second the velocity gets

maximum as shown in the velocity graph fig2.14 the effect can be observed in acceleration graph in

Fig2.15 were at the 6th second the acceleration reaches to zero. At the 10th second the velocity

reaches to zero as shown in the velocity graph fig2.14 the effect can be observed in acceleration

graph in Fig2.15 were at the 10th second the acceleration reaches to maximum value of 3.746deg/s2

then reaches to zero as the cylinder stroke ends.


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2.6.3 Result of angular velocity graph at stick hinge:

Fig 2. 16 Angular velocity at Stick hinge


The angular velocity graph at stick hinge is shown in the Fig2.16 has time in second in


in ADAMS the motion is given to hydraulic cylinder connected to stick the graph is plotted. As the

hydraulic cylinder is actuated in the time interval of 10s to 20s the graph is plotted between these

timings. From the graph for the scale down model (1:2) the result obtained is the maximum velocity

is 8.174deg/s. In which the for the first 6second the velocity increases from zero to maximum and

then in next 4 second the velocity decreases from maximum to zero.

2.6.4 Result of angular acceleration graph at stick hinge:


The angular acceleration graph at stick hinge is shown in the Fig2.17 has time in second in


function in ADAMS the motion is given to hydraulic cylinder connected to stick the graph is

plotted. As the hydraulic cylinder is actuated in the time interval of 10s to 20s the graph is plotted

between these timings. From the graph for the scale down model (1:2) the result obtained is the


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maximum angular acceleration is 5.246deg/s2. In which the angular velocity is 3.19 deg/s2 is

observed at the beginning the transition from zero to 3.19deg/s2 takes in short time and as at the 16th

second the velocity gets maximum as shown in the velocity graph fig2.16 the effect can be

observed in acceleration graph in Fig2.17 were at the 16th second the acceleration reaches to zero.

At the 20th second the velocity reaches to zero as shown in the velocity graph fig2.16 the effect can

be observed in acceleration graph in Fig2.17 were at the 20th second the acceleration reaches to

maximum value of 5.246deg/s2 then reaches to zero.

Fig 2. 17 Showing Angular acceleration at stick hinge

2.6.5 Result of angular velocity graph at Boom hinge:


The angular velocity graph at boom hinge is shown in the Fig2.18 has time in second in


in ADAMS the motion is given to hydraulic cylinder connected to stick the graph is plotted. As the

hydraulic cylinder is actuated in the time interval of 20s to3 the graph is plotted between these

timings. From the graph for the scale down model (1:2) the result obtained is the maximum velocity

is 6.946deg/s. In which the for the first 6second the velocity increases from zero to maximum and

then in next 4 second the velocity decreases from maximum to zero.


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Fig 2. 18 Angular velocity at Boom hinge

2.6.6 Result of angular acceleration graph at Boom hinge:


The angular acceleration graph at boom hinge is shown in the Fig2.19 has time in second in


function in ADAMS the motion is given to hydraulic cylinder connected to boom the graph is

plotted. As the hydraulic cylinder is actuated in the time interval of 20s to 30s the graph is plotted

between these timings. From the graph for the scale down model (1:2) the result obtained is the

maximum angular acceleration is 3.962deg/s2. In which the angular velocity is 2.143 deg/s2 is

observed at the beginning the transition from zero to 2.143deg/s2 takes in short time and as at the

26th second the velocity gets maximum as shown in the velocity graph fig2.18 the effect can be

observed in acceleration graph in Fig2.19 were at the 26th second the acceleration reaches to zero.

At the 30th second the velocity reaches to zero as shown in the velocity graph fig2.18 the effect can

be observed in acceleration graph in Fig2.19 were at the 30th second the acceleration reaches to

maximum value of 3.9628deg/s2 then reaches to zero.


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Fig 2. 19 Showing Angular acceleration at Boom hinge

2.7 Modeling of Backhoe in CATIA:

The 3D geometric model of the parts of the backhoe are created by constructive boundary

method, where initially sketcher work bench is used and part work bench is used to create the part

model and assembly work bench is used to assemble all the parts and to analyze the clash and

finally the various parts of backhoe is shown in the Fig below.

Fig 2. 20 Boom & Bucket modeled in CATIA


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Fig 2. 21 Bucket link & Bucket quick attach link modeled in CATIA

Fig 2. 22 Stick and Pivot bucket link modeled in CATIA

Fig 2. 23 Backhoe assembly created in CATIA


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PART-C

CHAPTER 3

________________________________________________________________________________

3.0 Introduction:

In this chapter the modeled backhoe part is converted into neutral IGES format and imported into

HYPER MESH 2009 software and meshing is carried out at 3forms which are:

i) Bucket alone.

ii) Boom and stick together.

iii) Whole assembly together – Bucket, Stick and Boom.

In the mesh elements the various properties of the elements are defined such as element type is

defined in ET-reference the material is defined as steel and the properties of young’s modulus,

density and Poisson’s ratio is defined before exporting to the ANSYS.

3.1 Finite element model conversion:

The various elements used in meshing are;

Solid 45:

It is used in 3 solid dimensional structures, were tetrahedral element has 5 nodes each node

has 3DOF which are translation along X, Y and Z axis. The output of the element is nodal

displacements included in the overall nodal solution. As for the assignment stress distribution has to

be found solid45 is capable of producing the results the element is selected for all the structures of

solid parts such as boom, stick and bucket.

Fig 3. 1 Showing Solid45 element DOF


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Mass21:

The mass element has 6 DOF, 3 translations and 3 rotations along X, Y and Z axis. The

mass element is defined by a single node, concentrated mass components. As in the pin joints it is

required to distribute and transfer the forces to one component to other such as boom to stick joint

the load is applied to the mass node and distributed through rigid elements.

Fig 3. 2 Showing Mass21 element DOF

CERIG:

These elements used to generate rigid region. The first node picked will be the master node,

and subsequent nodes picked will be slave nodes. These 1D elements are used to transfer the forces

applied to the mass node to the components these elements are used with mass nodes at the pin

joints.

3.1.1 Bucket:

The scale down model (1:2) of the bucket modeled using in CATIA R16 is converted into the finite

element model by meshing and applying the boundary condition in Hyper mesh 2009 software. The

meshed model is shown in the Fig3.3. Table 3. 1 Element characteristics of Bucket

Element Types

used

i) Solid 45

ii) Mass21

iii) Cerg

Element shape Quad, Tetrahedral element

Jacobian Minimum jacobian is 1.00 - 0% failed

Volume skew The minimum tetra collapse is 0.91 – 1

% failed

Aspect ratio The maximum aspect ratio is 4.32 –

0% failed. Fig 3. 3 Bucket meshed in HYPERMESH


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The details of the mesh are shown in Table-1 the results are attached in [Appendex-1]. The 1D

mass and rigid element are used at the pin joints. Before exporting to the ANSYS the elements are


density and Poisson’s ratio is defined in hyper mesh itself.

3.1.2 Boom and stick:

For the FEA analysis as the boom and stick is to be analysed together the scale down model

(1:2) of the stick and the boom part modeled using in CATIA R16 is converted into the finite

element model by meshing and applying the boundary condition in hyper mesh 2009 software. The

meshed model is shown in the Fig3.4.

The details of the mesh are shown in Table-1 the results are attached in [Appendex-1]. The 1D

mass and rigid element are used at the pin joints. Before exporting to the ANSYS the elements are


density and Poisson’s ratio is defined in hyper mesh itself.

3.1.3 Backhoe assembly:

For the FEA analysis as the whole backhoe assembly has to be analysed together the scale

down model (1:2) of the stick, boom and bucket part modeled using in CATIA R16 is converted

Element

Types used

i) Solid 45

ii) Mass21

iii) Cerg

Element

shape

Quad, Tetrahedral element

and link

Jacobian Minimum jacobian is 1.00 -

0% failed

Volume skew The minimum tetra collapse

is 1.00 – 17 % failed

Aspect ratio The maximum aspect ratio is

136.09 – 1% failed.

Table 3. 2 Element characteristics of Boom and Stick Fig 3. 4 Boom & Stick meshed in HYPERMESH


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into the finite element model by meshing and applying the boundary condition in hyper mesh 2009

software. The meshed model is shown in the Fig3.5.

Fig 3. 5 Showing assembly meshed in HYPERMESH

The details of the mesh are shown in

Table-1 the results are attached in [Appendex-1].

The 1D mass and rigid element are used at the pin

joints. Before exporting to the ANSYS the

elements are defined in ET-reference the material

is defined as steel and the properties of young’s

modulus, density and Poisson’s ratio is defined in

hyper mesh itself.

Element

Types used

i) Solid 45

ii) Mass21

iii) Cerg

Element

shape

Link, Quad, Tetrahedral

element

Jacobian Minimum jacobian is 1.00 -

0% failed

Volume skew The minimum tetra collapse

is 1.00 – 2 % failed

Aspect ratio The maximum aspect ratio is

148.32 – 1% failed.

Table 3. 3Element characteristics of Backhoe assembly


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3.2 Boundary conditions used for analysis:

3.2.1 Boundary conditions and load analysis of bucket:

As the bucket is scale

down, model the breaking force

obtained by the calculation is

8000N. The applied force on to

the bucket is 4000N , in order to

apply load on to the bucket by

considering the breaking force

acting on the bucket wedge, were

the bucket used to dig the soil the

force of 400N is applied in

ADAMS the values are measured

at the joints and those values are

taken as the input to the ANSYS software the values of the forces obtained at the joint are X-axis =

1009N, Y-axis = 6004N and Z-axis = -2124N. These values are applied in the ANSYS on the mass

node created as shown in the Fig3.6.

3.2.2 The Displacement of the bucket:

Fig 3. 7 Showing Displacement sum vector results of bucket

Fig 3. 6 Loads and Boundary conditions on Bucket


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By applying the loads obtained in the ADAMS and by appropriate constraining the result of the

displacement sum vector obtained is 0.329876mm were the displacement is maximum at the face

were the digging wedges are place in the bucket. The displacement is minimum at the area were all

DOF constrain is applied as shown in the Fig3.8.

3.2.3 Vonmises stress in the bucket:

Fig 3. 8Showing Vonmises stress results of bucket

As per the theory of failure vonmises theory gives the best results for the multi axial loading

component therefore in order to determine the failure of the bucket the vonmises stress is found

which should be less while compared to the yield strength of the material after considering the FOS.

In the bucket the maximum Vonmises stress is obtained at the pin joint were all DOF is constrained

were the stress value is 149.236N/mm2.

3.2.4 Boundary conditions and load analysis of Stick and boom:

As the boom and stick is scale down model, the breaking force obtained by the calculation is

8000N. The applied force on to the bucket wedge is 4000N, in ADAMS the values are measured at

the joints and those values are taken as the input to the ANSYS software the values of the forces

obtained at the joint are:

i) X-axis = 1009N, Y-axis = 6004N and Z-axis = -2124N.

ii)X-axis = 1758N, Y-axis = -403N and Z-axis = 0N.


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iii)X-axis = -1182N, Y-axis = 164N and Z-axis = -127N.

These values are applied in the ANSYS on the mass node created as shown in the Fig().

Fig 3. 9 Boundary condition and loads on stick & Boom assembly

3.2.5 The Displacement of the boom and stick:

Fig 3. 10 Displacement results of stick & Boom assembly


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By applying the loads obtained in the ADAMS and by appropriate constraining the result of

the displacement sum vector obtained are 4.969 mm were the displacement is maximum at the

region of the pin joint connecting the bucket were the force due to the bucket will be maximum.

The displacement is minimum at the region of the boom and at the larger cross section of the stick

as shown in the Fig3.10.

3.2.6 Vonmises stress in the stick and boom:

Fig 3. 11 Showing Vonmises stress result of stick & Boom assembly



component therefore in order to determine the failure of the boom and stick assembly the vonmises

stress is found which should be less while compared to the yield strength of the material after

considering the FOS. In the bucket the maximum Vonmises stress is obtained at the pin joint were

all DOF is constrained and the forces are applied and in the stick part the stress pattern is found at


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the area were the change in the cross section takesplace. The maximum vonmises stress value

obtained for the scale down model is 195.504N/mm2.

3.2.7 Boundary conditions and load analysis of backhoe assembly:

The backhoe assembly consist of boom, stick and bucket, for the scale down model, the

breaking force obtained by the calculation is 8000N. The applied force on to the bucket wedge is

4000N. In ADAMS the values are measured at the joints and those values are taken as the input to

the ANSYS software the values of the forces obtained at the joint are:

i) X-axis = 1009N, Y-axis = 6004N and Z-axis = -2124N. - Stick and bucket joint

ii) X-axis = 1758N, Y-axis = -403N and Z-axis = 0N. – Stick and boom joint

iii) X-axis = -1182N, Y-axis = 164N and Z-axis = -127N. – Boom end joint

iv) X-axis = 0N, Y-axis = 4621N and Z-axis = -123N. - Bucket joint

These values are applied in the ANSYS on the mass node created as shown in the Fig3.12.

Fig 3. 12 Showing boundary condition on Backhoe assembly

3.2.8 The Displacement of the backhoe assembly:


By applying the loads obtained in the ADAMS and by appropriate constraining the result of

the displacement sum vector obtained are 0.22129 mm were the displacement is maximum at the


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region of the pin joint end of boom connecting to the tractor and at the wedge portion of bucket

were the force due to the digging occurs shows maximum displacement. For the backhoe structure

as the forces at the different joints tries to make the structure into the equilibrium condition the

displacement is found less in the most of the region of the backhoe assembly Fig3.13.

Fig 3. 13 Showing displacement results of Backhoe assembly

3.2.9 Vonmises stress in the stick and boom:

Fig 3. 14 Showing Vonmises stress results of Backhoe assembly


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component therefore in order to determine the failure of the backhoe assembly consit of bucket,

boom and stick assembly the vonmises stress is found which should be less while compared to the

yield strength of the material after considering the FOS. In the bucket the maximum Vonmises

stress is obtained at the pin joint were the force of the bucket is applied. For the backhoe structure

as the forces at the different joints tries to make the structure into the equilibrium condition the

stressed regions are found less and the maximum vonmises stress value obtained for the scale down

model is 119.389N/mm2.

3.3 Improving the asthetic without compromising the strength:

3.3.1 Modification in Boom:

The beam carting the uniformly distributed load is

shown in the Fig3.15 which is similar to the boom

structure, were the maximum bending moment

occurs at the middle of the beam similar to this in

boom also the bending moment will be maximum

at the middle therefore while modifying the

structure for the aesthetic purpose thaking this into

consideration the structure is modified the initial

shape is shown in the Fig3.16. The modified shape

is shown in Fig3.17.

Fig 3. 16 Boom Modeled - Before modifying shape

Fig 3. 15 Idealization of simply supported beam as Boom


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Fig 3. 17 Boom Modeled - after modifying shape

3.3.2 Modification in stick:

In order to improve the aesthetic without out

compromising the strength the shape is been modified in stick

were initial model there is sharp edges at the change in cross

section which will results in stress concentration as shown in

the Fig3.18 were the sudden change in the cross section with

sharp edges is modified by providing the radius to the section at

the region. The Fig3.19 shows the initial model and Fig3.20

shows after modifying the section.

Fig 3. 19 Stick modeled before modification of shape

Fig 3. 18 Showing stress concentration at the sharp corner


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Fig 3. 20 Stick modeled after modification of shape

3.4 Result validation after optimisation of structure:

3.4.1 Displacement result comparison:

In the Fig 3.21. The comparison of the results is shown before and after modifying the shapes of

boom and stick for optimization purpose. From the Fig it can be observed that the displacement

region remains same for the both the cases but the displacement slightly increases 1.12mm in the

optimized structure but still it is preferred as the Vonmises stress distribution shows the better

results.

Fig 3. 21 Displacement result comparison before and after optimization


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3.4.2 Vonmises Stress result comparison:

While comparing the Vonmises stress distribution the stress value is decreased for the optomised

structure, were the initial stress value is 195.504 N/mm2 and the value obtained after optimization is

172.581N/mm2. This is lesser than the initial value, the Fig3.22 shows the comparison of Vonmises

stress before and after optimization.

Fig 3. 22 Vonmises stress result comparison before and after optimization


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Learning outcomes:

The module provides the understanding and applications of the basics and the working

principles of different types of machinery. The knowledge gained in the area of design of different

types of mechanical machinery to meet the various functional and operational requirements. The

application of computer aided engineering tools such as CATIA, HYPERMESH, ANSYS and

ADAMS for design, modeling, simulation, analysis, synthesis and optimization of machine

components and system. The module covers the application of the knowledge gained from all the

modules learned before. This includes machine design criteria and general design procedure and the

various mechanical Properties, the mechanical behavior of materials under various loading and the

concepts of strength and failure resistance. The module covers the calculations related to the simple

and complex machines related to wheel, axle and pulleys. The various to be made while designing

the components such as categorizing into compound and plane stress system and considering stress

due to torsion, stress due to bending and performing the stress analysis. The session on fatigue

covers the basic concepts and the importance of the fatigue, Influence of material property,

composition, microstructure and processes on fatigue behavior of metals. The various terminologies

used in fatigue, various types of the fatigue cycles and calculation of fatigue life of the component.

The concepts of crack propagation stress concentration and various methods to improve fatigue life.


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References

________________________________________________________________________________

[1] Unknown, “High Speed Steel” http://www.sharusteels.com/high-speed-steel.html Retrieved on

03/08/2012.

[2] Kadam M.S, Pathak S.., “Experimental Analysis and Comparative Performance of Coated and

Uncoated Twist Drill Bit Dry Machining” http://www.ijrmet.com/vol1/kadam.pdf retrieved on

11/08/2012.

[3] Unknown, “Titanium nitride” http://en.wikipedia.org/wiki/Titanium_nitride retrieved on

07/08/2012.

[4] Pravardhan S. Shenoy, “Dynamic Load Analysis and Optimization of Connecting Rod”

https://www.forging.org/system/files/field_document/DynamicLoadAnalysis.pdf retrieved on

09/08/2012.

[5] Harry Bhangu, “Effect of design and material defects on gas turbine blade failures”

http://www.braemarsteege.com/lecturenotes/lecture65.pdf retrieved on 11/08/2012.

[6] David Parsons, “Ceramic coatings for jet engine turbine blades”

http://www.carbonbrainprint.org.uk/pdf/CBrainprint-CS01-JetTurbines.pdf retrieved on

06/08/2012.

[7] Riversedge, “Exposed Ductwork Showcases Design and Functionality”

http://www.lindabusa.com/dokumenter/CaseStudyRiversedge.pdf retrieved on 07/08/2012.

[8]Unknown, “Basic Notes on Factor of Safety”

http://www.roymech.co.uk/Useful_Tables/ARM/Safety_Factors.html retrieved on 11/08/2012.


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Appendex-1

Elements check in Hyper mesh:


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Appendex-2


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backhoe loader finite element analysis

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