avoiding fracture failure of a crusher disk in a lamp re ...831563/fulltext01.pdf · the crusher...
TRANSCRIPT
Master's Degree Thesis ISRN: BTH-AMT-EX--2012/D-01--SE
Supervisors: Ansel Berghuvud, BTH Magnus Nilsson, MRT Systems International AB, Karlskrona, Sweden
Department of Mechanical Engineering Blekinge Institute of Technology
Karlskrona, Sweden
2012
Mahesh Meesala Swapna Armoor
Avoiding Fracture Failure of a Crusher Disk in a Lamp Re-
cycling Machine
1
Avoiding Fracture Failure of a
Crusher Disk in a Lamp
Re-cycling Machine
Mahesh Meesala, Swapna Armoor
Department of Mechanical Engineering
Blekinge Tekniska Hogskola,
Karlskrona, Sweden.
2012
Thesis submitted to completion of Master of Science in Mechanical
Engineering with emphasis on Structural Mechanics at the Department of
Mechanical Engineering, Blekinge Institute of Technology, and Karlskrona,
Sweden.
Abstract:
The crusher disk in lamp recovery device used for crushing aluminum
end caps is breaking while crushing for unknown reasons. Therefore it
is important for design engineers to be able to find out the possibilities
of fracture failure and also provide prevention methods for it during
design proposals. The scope of this thesis is to find out the reason for
failure, solution and prevention methods of the crusher disk in a lamp
recovery device. Hence the experiment will include theoretical
modeling followed by experimental work. Theory of essential work,
experimental and finite element methods using ABAQUS,
INVENTOR were used for analysis. Dynamic simulation in Autodesk
Inventor was performed to find the startup force. A finite element
analysis in ABAQUS was made in order to show stress concentration
on the disk. It provides effective method for experimentation. During
experimentation it is found that the failure occurs due to improper
design. It was Re-designed to prevent the problem.
Keywords:
Crushers, Fracture, Re-design, FEM, Simulation, ABAQUS, and
INVENTOR.
2
Acknowledgements
This work is carried out at the Department of Mechanical Engineering,
Blekinge Institute of Technology (BTH) and MRT Systems International
AB, Karlskrona, Sweden, under the supervision of Dr. Ansel Berghuvud
and Magnus Nilsson.
We would like to express our sincere gratitude to our supervisors, Dr.
Ansel Berghuvud, Department of Mechanical Engineering. Blekinge
Institute of Technology, Karlskrona, Sweden and Magnus Nilsson, MRT
Systems International AB, Karlskrona, Sweden for their inspirational
support. Their guidance and timely advices are strength to us. Without
their support and guidance, this thesis would not have been possible.
Finally we would like to thank our friends Rammohan K P, Cagatay
Bankaoglu, Mohammed Shafiq for helping us to get through difficult
times by providing timely support. We are very much thankful to our
beloved parents for their support and encouragement to complete our MS
studies. We convey our hearty wishes to our roommates in Sweden for
their assistance.
Karlskrona, June 2012
Mahesh Meesala
Swapna Armoor
3
Contents
1. NOTATIONS ..................................................................................................... 8
2. INTRODUCTION ............................................................................................. 9
2.1 Problem Statement ....................................................................................... 10
2.2 Aim and Scope ............................................................................................ 11
3. BACKGROUND .............................................................................................. 12
3.1 Related work ................................................................................................ 12
4. Studied System ................................................................................................. 13
4.1 Crusher Disk Working Performance ........................................................... 13
5. Theoretical Model ............................................................................................ 16
5.1 Introduction to ABAQUS ............................................................................ 17
5.2 Introduction to Finite Element Method ....................................................... 17
5.3 Introduction of Autodesk Inventor .............................................................. 18
5.4 Fundamentals of Fracture Mechanics .......................................................... 18
5.5 Potential Risk Factors .................................................................................. 19
5.6 Energy Methods ........................................................................................... 22
6. Experimental work .......................................................................................... 25
6.1 Experimental Setup...................................................................................... 25
6.2 Mechanical Testing...................................................................................... 27
6.2.1 Dynamic simulation by INVENTOR ................................................... 27
6.2.2 Results .................................................................................................. 27
6.2.3 Discussion & conclusion ...................................................................... 28
7. Modeling & Results ......................................................................................... 30
7.1 FEM using ABAQUS .................................................................................. 30
7.1.1 Assumptions ......................................................................................... 30
4
7.1.2 Pre-processing ...................................................................................... 30
7.1.3 Simulation ............................................................................................. 36
7.1.4 Post processing ..................................................................................... 36
7.2 Results ......................................................................................................... 36
7.3 Re-design of the part.................................................................................... 37
7.3.1 Mesh ..................................................................................................... 37
7.3.2 Results .................................................................................................. 38
8. Comparison of results ..................................................................................... 41
8.1 Comparison of present disk and re-designed disk ....................................... 41
9. Conclusion and Future work .......................................................................... 44
10. References ...................................................................................................... 45
5
List of Figures
Figure 1 :- Aluminum End caps .................................................................. 10
Figure 2: - Broken part during crushing .................................................... 11
Figure 3: - Assembly of Crusher Disk ........................................................ 13
Figure 4 : - Coordinated Approach ............................................................ 16
Figure 5: - Applied force ............................................................................ 23
Figure 6 : - Experimental setup of lamp recovery device ........................... 25
Figure 7 : - Crusher disk setup ................................................................... 26
Figure 8 : - Solid model of crusher disk ..................................................... 26
Figure 9 : - Dynamic simulation of crusher disk ........................................ 27
Figure 10 : - Start-up force ......................................................................... 28
Figure 11 : - Front sides drawing of the part ............................................. 31
Figure 12 : - Back side dimensions of the specimen ................................... 32
Figure 13 : - Applying Load ...................................................................... 34
Figure 14 : - Applied boundary condition .................................................. 35
Figure 15 : - Mesh of the present disk ........................................................ 35
Figure 16 : - Stress Analysis by applying load ........................................... 36
Figure 17 : - Re-Design of Crusher Disk ................................................... 37
Figure 18 : - Re-design disk meshes ........................................................... 37
Figure 19 : - Stress Analysis of re-designed disk ....................................... 38
Figure 20 : - Strain of re-designed disk ...................................................... 39
Figure 21 : - Reaction force of re-designed disk at nodes .......................... 39
Figure 22 : - Reaction forces comparison .................................................. 41
Figure 23 : - Displacement comparison ..................................................... 41
Figure 24 : - Comparison of stress ............................................................. 42
Figure 25 : - Comparison of strain ............................................................. 42
Figure 26 : - Maximum of Von Misses Stress ............................................. 46
Figure 27 : - Minimum of Von Misses Stress .............................................. 46
Figure 28 : - Max of 1st Principle Stress .................................................... 47
Figure 29 : - Max of 3rd
Principle Stress .................................................... 48
Figure 30 : - Min of 3rd
Principle Stress..................................................... 48
Figure 31 : - Max Displacement ................................................................. 49
Figure 32 : - Min Displacement ................................................................. 49
6
Figure 33 : - Max Safety Factor ................................................................. 50
Figure 34 : - Min Safety Factor .................................................................. 50
Figure 35 : - Max of Equivalent Strain ....................................................... 51
Figure 36 : - Min of Equivalent Strain ....................................................... 51
Figure 37 : - Max of 1st Principle Strain .................................................... 52
Figure 38 : - Max of 3rd
Principle Strain .................................................. 53
Figure 39 : - Min of 3rd
Principle Strain .................................................. 53
Figure 40 : - Load applied .......................................................................... 54
Figure 41 : - Displacement ......................................................................... 54
7
List of Tables
Table 1: - Chemical Compositions ............................................................ 14
Table 2 : - Properties of ductile cast iron .................................................... 15
Table 3 : - Material properties generated in ABAQUS .............................. 33
Table 4 : - Applied load .............................................................................. 34
Table 5 : - Re-designed disk results ............................................................ 40
Table 6 : - Comparison of both results ....................................................... 43
8
1. NOTATIONS
A Area
a Thickness [m]
E Young’s Modulus [MPa]
G Energy Release Rate [ ]
H Height [m]
Stress intensity factor [MPa ]
Fracture Toughness [MPa ]
P Load [N]
W Half the Width [m]
Function of specimen geometry
Stress [MPa]
Stress at Break [MPa]
Stress at fracture [MPa]
Strain [%]
Shear Stress [MPa]
F Applied Force [N]
v Velocity [m/s]
Angular velocity [rad/sec]
F Load capacity [N]
9
2. INTRODUCTION
The term sustainable development was defined in 1987 in the report
published by the Brunt land commission entitled ‘’our common future’’
as a form of community development that meets present day needs
without jeopardizing the chances of future generations to meet their needs.
This is a challenge that is becoming increasingly relevant. The tangible
effects of our actions and way of life on areas such as global warming,
represents a challenge for all members of society to go from words to
actions. It is essential that we develop new technical solutions to
overcome this problem [1].
Man has been using the earth’s natural resources without thinking about
needs of future generations to come. For this scientists started thinking
about the re-use of waste materials like mercury, fluorescent lamps, glass
etc. One of the most dangerous materials for nature is mercury which is
used in different kinds of lamps and monitors. After useful life of this
products scientists thought of re-using these products which causes
accumulation results in environmental degradation and effect future
generations. From this concept re-cycling process was put into practice.
Lamp recovery device is a recycling machine of aluminum end caps. In
this device crusher disk plays an important role for crushing aluminum
end caps. The crusher disk is breaking while crushing the aluminum end
caps. In this report we will be finding out the problem and solution for the
cause of fracture in crusher disk of a lamp recovery device which is a re-
cycling machine.
MRT system International AB is one of the world’s most leading
recycling companies plays an important role in recycling the wastes like
mercury, fluorescent lamps, glass, HID lamps, CRT’s batteries.
Aluminum end caps are shown below.
10
Figure 1:-Aluminum End caps
2.1 Problem Statement
Crusher disk in the Lamp recovery device plays an important role in
crushing aluminum end caps. During the work, disk in the crusher breaks
for unknown reasons, this failure is happening during in first few days or
in month’s time. In this thesis our aim is to find out the reason for this
failure and how we can avoid this failure. Materials which are feeding to
lamp recovery device are all different parts like aluminum end caps and
glass.
11
Figure 2: - Broken part during crushing
2.2 Aim and Scope
This thesis is titled as ‘’Avoiding fracture failure of crusher disk in lamp
recovery device ‘’. The aim of this thesis is to find out the cause of fracture
failure of crusher disk in a lamp recovery device and provide possible
solutions. The aim of this thesis is achieved through the following
objectives.
1. Identifying various risk factors for cause of failure
2. Selecting the major risk factor
3. Experimenting on appropriate risk factor which we have chosen above.
Software’s used: ABAQUS, INVENTOR
12
3. BACKGROUND
3.1 Related work
An investigation on the fracture failure of the crusher disk was done in
the year 2011 by Frashad Shafieian [2]. His document gives a good
knowledge about the failure risk factors of crusher disk. In report [2] only
investigations were done but where as in this report experimental work
will be conducted based on the new investigations.
Based on the report [2], major risk factors for failure are sorted out for
experimental purpose. An ongoing experiment is continuing in the
company MRT Systems International AB, Sweden to solve the problem in
order to increase the working performance and customer satisfaction.
In this report we mainly concentrate on crack propagation, Startup force
and change in geometry for better results, modal testing will be done by
using tools like Autodesk Inventor, ABAQUS.
13
4. Studied System
4.1 Crusher Disk Working Performance
Function of the rotary disk is to crush the aluminum end caps to use them
again. The rotary disk is mounted on a motor, with motor specifications
710 rpm and power of 4KW. In which motor speed is maintained constant
while crushing the metals. The material feeding is done randomly
according to the material fed to the crusher. There is no specific load limit
for feeding.
MRT Systems had a complaint that lamp recovery device is facing the
problem of disk breakage while crushing the aluminum end caps. In this
our aim is to find out why the disk is breaking and how we can avoid the
fracture failure.
Figure 3: - Assembly of Crusher Disk
14
4.2 Material Properties
The disk in the crusher is made up of grey cast iron ductile (ASTM-A536).
Which is fixed to the plate, in between four gears is attached to the rotary
disk for crushing purpose. Surface of these gears is finely finished in order
not to rub between the disk and gear. The chemical composition and
material properties of ductile cast iron are shown in below tables.
Table 1: - Chemical Compositions
Analyses Oven Gods
C 3.50 - 3.70 3.40 +/- 0.10
Si 1.40 +/- 0.05 2.40 +/- 0.10
Mn 0.20 – 0.25 0.20 – 0.25
P Max 0.06 Max 0.06
S Max 0.015 Max 0.015
Cu 0.39 – 0.40 -
Cr Max 0.05 Max 0.05
Ni Max 0.10 Max 0.10
Mg - 0.05+/-0.01
15
Table 2 : - Properties of ductile cast iron
Property Value in Metric Unit
Density 7.2
Modulus of Elasticity 172 GPa
Poisson’s Ratio 0.275
Thermal Expansion ( ) 11.6
Specific Heat Capacity 506
Thermal Conductivity 32.3
Electric Resistivity 6 ohm m
Tensile Strength 496 MPa
Yield Strength 345 MPa
Shrink 0.5-1.0 %
Shear Strength 372 MPa
Fatigue Strength 290 MPa
Hardness(Brinell) 200-260 BH
Wear Resistance Low
Corrosion Resistance Low
Weld Ability Low
Mach inability Good
Cost Ability Good
Shock Resistance Medium
The above details of material properties are provided by the company MRT
Systems International AB, Sweden.
16
5. Theoretical Model
It is always better to follow theoretical model along with experimental
model in order to get better results. Theoretical method like Finite
Element Method is used to find the solution for numerical method which
makes problems easier from complicated. Finite Element Method along
with ABAQUS is used to find the solution in theoretical method.
Theoretical modeling and simulation provides improved fundamental
understanding. By this, we can also re-use this knowledge in future
project development and efficiency of product development in company.
Figure 4 : - Coordinated Approach
17
5.1 Introduction to ABAQUS
Abaqus is software which is released in the year 1978. It is a software
application for finite element analysis and computer aided engineering.
Abaqus has four different core software’s.
a) Abaqus/CAE, Complete Abaqus Environment, which is used for
analyzing and simulation of mechanical components and also creates
finite element analysis result.
b) Abaqus/CFD, Computational Fluid Dynamics, it’s new version
c) Abaqus/ Standard, it deals with finite element analyzer to produce
implicit integration scheme.
d) Abaqus/Explicit, it is used to solve highly non-linear systems under
transient loads.
In this report Abaqus/CAE was used for simulation of the crusher disk in
finite element analysis.
By using the numerical methods like FEM, stress analysis of the particular
part can be done due to force. The special feature of Abacus is, design file
of other program can be imported to Abaqus for stress analysis of both
statistical and dynamic analysis. In this it is possible to mesh a part in
different ways. In order to motivate the mode shapes first we need to
know the most important thing modal analysis. In this the result is based
on the introduced points. By having this kind of software programs will be
helpful for engineers to save time and money for conducting the trial and
error method experiments. By using this kind of software we can try to
produce accurate results by doing trial and error methods [2, 3].
In this thesis out of four different core software’s ABAQUS /Explicit is
used to work for modal testing of crusher disk. By using this software,
stress concentration on the disk is found.
5.2 Introduction to Finite Element Method
The development of finite element method was started in the year 1950’s
in aerospace industry. In early days Finite Element Method was used only
18
for solving structural mechanics. Today Finite Element Method is
powerful tool for solving numerical solution of any differential equations.
The solutions obtained from the finite element method is based on the
either eliminating differential equations completely or rendering the
partial differential equation into an approximating system of ordinary
differential equations, which are numerically integrated using Euler’s
method or Runge-kutta method. In order to get better results FEM
transforms the differential equation problem into a system of algebraic
equations [4].
By using Finite Element Method it is easier to solve the problem in
theoretical model compared to analytical model. In order to make it easier
one of the reliable software ABAQUS is used to find the specific load,
stress concentration and weak points of the part or structure. Abaqus along
with Finite Element Method is helpful for re-designing the part.
5.3 Introduction of Autodesk Inventor
Autodesk Inventor is design for creating 3D digital prototypes for
visualization and simulation. Inventor is used for integrated motion
simulation and assembly stress analysis. It is indirectly competes with
solid works and solid Edges.
In this thesis dynamic simulation in Auto desk Inventor was performed to
find out the start up-force of the crusher disk in lamp recovery device.
5.4 Fundamentals of Fracture Mechanics
Fracture mechanics is the field of mechanics which is subjected to the study
of crack propagation in materials. For analyzing the driving force on a
crack, fracture mechanics uses analytical method solid mechanics for
cracked bodies subjected to stress and strain [5]. In improving the
mechanical performance of materials and components fracture mechanics
plays an important role. It is also a useful tool for characterizing crack
growth by fatigue [8].
Some of the important terms which cause fractures for driving force are
1. Direct load
19
2. Chemical reaction
3. Temperature
5.5 Potential Risk Factors
The main objective of this thesis is to find the problem and solve for it in
order to increase the working performance and customer satisfaction [2].
Before starting the work, potential risk factors for cause of breakage are
identified and listed below. From the list of potential problems first we
start with less likely reasonable for failure and then concentrate on major
risk factors. Eliminate the less likely reasons and start studying the
theoretical model of major problems by this theoretical models and
simulations are used to design good experiments [4]. But still it’s always
not possible to predict exact problems before performing the experimental
work. In one thesis it’s not possible to investigate all potential risk factors,
so some major factors are considered and tested experimentally [4].
The following risk factors which may cause the failure and breakage of
crusher disk are
1. Crack propagation.
2. Fatigue.
3. Design of the part.
4. Start- up force.
5. Temperature of the working area.
6. Poor maintenance.
7. Impact loading.
8. Chemical reaction.
9. Wear out.
20
10. Wrong feeding.
Potential reasons for the above mentioned factors are
1. Crack propagation: - When the stress intensity factor k1 of the
specimen reaches critical value, crack in the specimen starts to propagate
and then material resistance load reaches to its peak. Where k1 is fracture
toughness. Crack propagates when k1>kc[7]. In energy criteria crack
propagation was analyzed and found that the material uses its stored energy
to produce new crack. If there is no enough stain energy stored, crack
growth will be stopped. When the change in the energy G is less than
material resistance R no crack growth will be there until and unless applied
force is high. When the change in the energy G is more than the material
resistance R or more than the resistance R then it will follow unstable
growth and there may be possibility of failure of the entire material [7].
Crack growth depends on the rate of change of driving force. Cracked disk
subjected to the remote tensile stress, tensile stress cannot be transmitted
through a crack. The lines of force are diverted around the crack resulting
in a load stress concentration. When there is a high toughness there is a
possibility of crack [8].
2. Fatigue: - Fatigue is a progressive failure that occurs due to dynamic
and fluctuating stresses. Repeated loading components may lead to break
even at low load levels, the stresses in the material are less than the tensile
strength or than yield limit of the material. Due to this failure of material
may occur, this failure is called fatigue. Fatigue phenomenon is known for
past 150 years but still material fatigue is considered as common it’s all
depends on the how fatigue is defined. Sometimes all mechanical failures
are due to fatigue [8].
Primary reason for the failure of structural components is fatigue. The
fatigue crack life has two parts
a) Initiation
21
b) Propagation
a) Initiation:-In this phase dislocation plays a major, dislocation piles up
and form structure persistent slip band (PSB) after a large number of
loading cycles.
b) Propagation: - surface component falls below due to extrusion and
intrusion. The movement of material along the slip planes produces tiny
particles stress raises and produce crack propagation [5].
3. Design of the part: - Design of the part is considered to check whether
the design of the part behavior is reasonable or not. For this one way is to
analyze the part by using Autodesk Inventor and the other way is to mesh
the part by applying random application of load in different direction with
the help of finite element method in ABAQUS. If we can find any errors
or difficulty in design it can be considered for further experimentation.
4. Start-up force: - The motor speed in the crusher disk of a lamp
recovery device starts from 0-710 rpm in seconds so there may be a
possibility of producing sudden force in it. If the machine starts several
times in a day, due to sudden force on the disk may lead to cause breakage
or failure of the disk.
5. Temperature of working area: - Depends on the material properties
specific working temperatures are allotted. If the material is used in below
or above particularly mentioned temperatures, this will change the
working characteristics of the material and it may lead to failure. In order
to avoid this problem it should it mentioned clearly on the part before
selling the product. By this customers will aware of it.
6. Poor Maintenance: - proper care should be taken while using the part
for better efficiency. If there is no proper maintenance of this part there
may be chances of getting struck of materials. If the machine starts and
stops frequently without clearing the struck materials there may be most
possibility of breakage of the part [2].
22
7. Impact Loading: - The design of the test specimen is similar in all
standards, symmetry directions of the specimen considered always [5].
Impact loading in the lamp recovery device produces sudden force on the
disk. Due to sudden forces high transient stresses develops on the disk and
produces the shock wave propagation, which creates serious consequences
on the disk. If the load on the disk is more than expected, may lead to
cause breakage on the part because of overload.
8. Chemical force contamination: - Chemical reaction may take place
between the metals and the crusher disk material gray cast iron. If it
happens the possibility of failure of the part is high. If this kind of failure
takes place we can avoid by coating the material with ceramic metals.
9. Wear out: - All parts are designed to be used for particular time period
for usage. If the time period is used for long period than the designed time
period there comes a wear out problem so this may lead to failure.
10. Wrong feeding: - While feeding metals to the crusher disk special
care should be taken in order to avoid problems. If wrong feeding is done
to the crusher because of material resistance can cause failure for disk [2].
5.6 Energy Methods
External forces are applied to the beam where it stores in the form of
stress and elastic deformation. Energy methods are completely
independent methods for stress/strain methods more convenient for
applying load. Theory of beams is the best method. Finding deformation
for particular point is easy in this theorem. Load to be applied on the
crusher disk is derived and shown below.
23
Figure 5: - Applied force
=
=
[ ]
=
=
=
F =
E = Young’s modulus (or) Modules of Elasticity
I = Moment of Inertia, I =
= mass of the Wheel
= Velocity
24
By applying the given values of the crusher disk in the equation
F =
Mass of the gear =0.48 kg
Velocity vg= 74.35 m/s
Diameter of the Nob = 14mm
Young’s modulus E= 172 GPa
We get F=586 N
25
6. Experimental work
6.1 Experimental Setup
In order to know the motor speed and start up force test was performed in
the company MRT Systems on lamp recovery device. Figure 6.1 is shown
below. Crusher disk is mounted on the motor shaft, material feeder is
connecting to the crusher disk in order to feed materials to the crusher.
Outlet of the lamp recovery device is connected to the collector, which
collects the recycled materials. Materials are feed to the crusher through
inlet which is fixed above the crusher. After crushing the materials, it goes
to the collector through the outlet of the device.
Figure 6 : - Experimental setup of lamp recovery device
26
Figure 7 : - Crusher disk setup
Figure 8 : - Solid model of crusher disk
27
6.2 Mechanical Testing
6.2.1 Dynamic simulation by INVENTOR
In order to check whether the problem is occurring due to crack
propagation or by fatigue testing on the motor speed was performed in the
company MRT Systems, to find startup force of the disk. At present the
speed of the motor is maintained 0-710 rpm in 3-4 seconds. It can produce
sudden force on the disk. Due to it there may be a possibility of breakage,
in order to check whether the startup speed produces sudden force on the
disk, this test was done and shown in the figure below.
Figure 9 : - Dynamic simulation of crusher disk
6.2.2 Results
This test is performed in the Autodesk Inventor by applying the proper
speed , velocity and mass of the wheel. It is calculated from Relay Ritz
energy method by using the speed of motor as shown below.
Mass of the wheel =0.350kg
28
v=
Where N=speed of the motor in rpm
v=
= 74.35 m/s
Figure 10 : - Start-up force
6.2.3 Discussion & conclusion
The disk has been analyzed for the forces acting upon it. Results from
dynamic simulation in Auto desk Inventor have been recorded. The start-
up force has been found out. If this start-up force on the disk is high there
will be high possibility of crack propagation and fatigue, because start up
0,000
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
0 5 10 15 20 25 30
Time ( s )
Chart Title
Force[1] (2D
Contact:3) ( N )
Force[2] (2D
Contact:3) ( N )
Force[3] (2D
Contact:3) ( N )
Force (N)
29
force is the main culprit for it. But here start up force of the crusher disk
reaches to 342 N in 0.08342 seconds at this speed, no sudden forces seem
to be developed. In the above figure 6 start up force in Y- axis is shows 0
to 400N. (But here rest of the points are extra, this are automatically
generated in this software). By this we concluded that the first two
potential risk factors are not reasons for failure so next risk factor design
of the part is considered for further experimentation.
30
7. Modeling & Results
7.1 FEM using ABAQUS
By startup force test we concluded that the first two potential risk factors
are not reasons for failure so next risk factor design of the part is
considered. In this work, Abaqus/CAE is used to create easy and quick
producing of the part. For finite element modeling Abaqus is most
commonly used tool in industry. In which complicated engineering tasks
can be solved easily. In this the proper boundary conditions and the loads
are applied to the part [3].
7.1.1 Assumptions
In order to keep model simple some assumptions are followed.
1. Materials are assumed to be isotropic.
2. Position’s ration is given as 0.275 for the material grey cast iron
3. Homogeneous materials are considered.
7.1.2 Pre-processing
Disk part model is generated and model of input file was stored.
Particular steps are followed to create a model are
a) Part
In order to create a model first basic elements are considered. A three
dimensional model, deformable, solid part with extrusion and sketcher
size of 200mm largest dimensions of our model was selected. According
to the below dimensions sketch was drawn [10].
31
Figure 11 : - Front sides drawing of the part
The model was created in two parts front side is drawn according to the
above figure 7 dimensions and back side of the disk is drawn according to
the below figure 8 dimensions [10].
32
Figure 12 : - Back side dimensions of the specimen
33
b) Properties
Mechanical properties of the material grey cast iron are given
Table 3 : - Material properties generated in ABAQUS
c) Assembly
In order to change a dependent instance’s mesh, command assembly >
side by side was used to get final model shape.
d) Step
In this step module, load and boundary conditions are parameters of
interest. For field and history outputs, static step was defined and pre-
selected parameters were used therefore step two simulation was defined.
e) Load
Load was applied in the boundary conditions. Centre of the disk was fixed
and the load of 586N was applied. Load is calculated from the mass of the
wheel.
34
Load and Moment of Constraints
Table 4 : - Applied load
Figure 13 : - Applying Load
Constraint Name Load
Fixed Constraint 586N
35
Figure 14 : - Applied boundary condition
f) Mesh
In order to generate finite element mesh module was used. A 4 node-
linear tetrahedron quadratic viscosity was used.
Figure 15 : - Mesh of the present disk
36
7.1.3 Simulation
a) Job
A job was created in the job module and submitted for analysis, after
finishing all the tasks necessary to create the model.
7.1.4 Post processing
a) Visualization
In visualization module results are shown in graphically from different
methods. Reaction forces, stress, strain and displacement at the edge of
the Nob on disk was shown in this. This file is used for simulation
purpose.
7.2 Results By applying the load on the Nob of the disk, we found that the stress
concentration is high. Due to this the crusher disk brakes, so in order to
find the solution for this re-design of the disk was done and discussed in
below session 7.3. Stress concentration on the disk is 5.120e+03
Figure 16 : - Stress Analysis by applying load
37
7.3 Re-design of the part
In order to solve the problem, discussed in the section 7.2 the re-design of
the crusher disk was done. It is breaking due to high stress. In order to
avoid this, supporting wings are given back side of the crusher disk. By
this load distribution will be on all the wings not just on one wing.
Re-design of the disk was done based on the following steps, already
which we have discussed in the section 7.1. For this even back side also
drawn by following same rules.
Figure 17 : - Re-Design of Crusher Disk
7.3.1 Mesh
Figure 18 : - Re-design disk meshes
38
7.3.2 Results
Stress concentration on the Nob of crusher disk is reduced after the re-
design. The results obtained for re-designed disk are shown below.
a) Max Stress
Figure 19 : - Stress Analysis of re-designed disk
b) Max Displacement
Figure 20 : - Displacement of re-designed disk
39
c) Max strain
Figure 20 : - Strain of re-designed disk
d) Reaction force at nodes
Figure 21 : - Reaction force of re-designed disk at nodes
40
Field outputs of Re-designed Disk
Table 5 : - Re-designed disk results
Field O/P’s Max Values
Max Stress( ) 3.792 Mpa
Displacement(S) 6.661 C/m²
Max Strain(E) 2.575
Reaction force at nodes(RF) 1.103 N
41
8. Comparison of results
8.1 Comparison of present disk and re-designed disk
a) Reaction forces at nodes
Figure 22 : - Reaction forces comparison
b) Displacement
Figure 23 : - Displacement comparison
42
c) Stress
Figure 24 : - Comparison of stress
d) Strain
Figure 25 : - Comparison of strain
43
Table 6 : - Comparison of both results
Field O/P’s Present Disk Re-designed Disk
Mass 2.909 kg 3.318 kg
Volume 401285.078 460848.222
Max Stress( ) 5.120 MPa 3.792 Mpa
Displacement(S) 1.157C/m² 6.661 Cm²
Max Strain(E) 3.217 2.575
Reaction force at
nodes(RF) 4.118 N 1.103 N
44
9. Conclusion and Future work
In this thesis finite element modeling and physical test were performed to
find and solve the problem for the failure of crusher disk in lamp recovery
device. Results obtained from the analyses were found to be satisfactory.
Initially the stress distribution on the specimen was calculated by using
the finite element model in ABAQUS/CAE by applying the calculated
load. High stress concentration on the crusher disk will be a reason for
breakage of specimen or the machine part.
Start up force of the crusher disk was found by performing Dynamic
simulation in Autodesk Inventor.
Re-design of the disk was done to avoid breakage. In the new design, four
wings were added on the back side of the crusher disk in order to
distribute the stress in between them. These wings will serve as support to
the disk. This way the breakage problem of the disk could be solved.
The results obtained from the analyses of re-designed disk showed better
values in comparison with that of present crusher disk results. Stress
distribution, displacement, reaction force results are compared for both the
disks.
Good match obtained in comparison between physical test and model test
results. Load is calculated from the theory of energy methods, it is applied
on crusher disk to find stress concentration.
The results which we obtained in this report were satisfactory and
approved by the company. The disk will now be manufactured and
employed in the company. This way we contributed to the company in
solving the problem.
As future work the material blockage also can be considered while solving
the problem. In Finite Element Modal we can module it in such away an
additional force put against the rotation of disk that might simulate the
blockage.
45
10. References
1. Oluf langhelle, Sustainable Development: Exploring the ethics of our
common future, International political science review (1999), DOI:
10.1177/0192512199202002.
2. Frashad Shafieian, Investigation on failure of a crusher disk in a
mercury recovery device, master thesis, ISRN: BTH-AMT-EX-2011/D-
05-SE, Department of Mechanical Engineering, Blekinge, Karlskrona,
Sweden, 2011.
3. ABAQUS 6.9 DOCUMENTATION.
4. Göran Broman, Computational Engineering, Department of Mechanical
Engineering, Blekinge Institute of Technology, Karlskrona, Sweden,
2003.
5. T.L.Anderson, Fracture Mechanics Fundamentals and Applications-
Third Edition, 1995.
6. C. p. Buckley, Material Failure, Lecture Notes, University of Oxford
UK, 2005.
7. Muhammad Shahid Iqbal, Tearing Fracture and Microscopic Analysis
of Laminate –Towards Sustainable packing, Master thesis, ISRN: BTH-
AMT-EX-2007-03-SE.
8. Tore Dahlberg Anders Ekberg, Failure Fracture Fatigue, An
Introduction, studentlitteratur 2002, ISBN 91-44-02096-1.
9. Autodesk Help: http://wikihelp.autodesk.com/Inventor/enu/2012.
10. Crusher disk sketches provided by company MRT Systems.
46
Appendix
Results generated in Autodesk Inventor
Max and Min of Von Misses Stress
Figure 26 : - Maximum of Von Misses Stress
Figure 27 : - Minimum of Von Misses Stress
47
1st Principle stress [Maximum, Minimum]
Figure 28 : - Max of 1st Principle Stress
Figure 30 : - Min of 1st Principle Stress
48
3rd
Principle Stress [Maximum, Minimum]
Figure 29 : - Max of 3rd
Principle Stress
Figure 30 : - Min of 3rd
Principle Stress
49
Maximum and Minimum Displacement
Figure 31 : - Max Displacement
Figure 32 : - Min Displacement
50
Maximum and Minimum Safety factor
Figure 33 : - Max Safety Factor
Figure 34 : - Min Safety Factor
51
Maximum and Minimum Equivalent Strain
Figure 35 : - Max of Equivalent Strain
Figure 36 : - Min of Equivalent Strain
52
Maximum and Minimum of 1st Principle Strain
Figure 37 : - Max of 1st Principle Strain
Figure 40 : - Min of 1st Principle Strain
53
Maximum and Minimum of 3rd
Principle Strain
Figure 38 : - Max of 3rd
Principle Strain
Figure 39 : - Min of 3rd
Principle Strain
54
Load applied
Figure 40 : - Load applied
Figure 41 : - Displacement
School of Engineering, Department of Mechanical Engineering Blekinge Institute of Technology SE-371 79 Karlskrona, SWEDEN
Telephone: E-mail:
+46 455-38 50 00 [email protected]