IJRI-ME-02-030 FATIGUE FAILURE ANALYSIS OF STEAM TURBINE SHAFT USING FEM TECHNIQUE

International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET)
International Journal of Research and Innovation in
Mechanical Engineering (IJRIME)
FATIGUE FAILURE ANALYSIS OF STEAM TURBINE SHAFT
USING FEM TECHNIQUE
D.Jojappa 1 , K.Naresh babu 2 , K.krishnaveni 3 .
1 Research Scholar, Department of Mechanical Engineering, Chebrolu engineering college, Guntur, AP, India.
2 Assistant professor, Department of Mechanical Engineering, Chebrolu engineering college, Guntur, AP, India.
3 Associate professor, Department of Mechanical Engineering, Chebrolu engineering college, Guntur, AP, India.
Abstract
The aim of the project is to locate best constrain location by evaluating steam turbine shaft with different materials.
Initially data collection will be done to understand rectification methodology and approach.
A 3D model of shaft will be prepared and exported into IGES (inertial graphical exchanging specifications) format to
conduct further work in ANSYS.
Structural analysis will be carried out on assembly to evaluate structural characteristics.
Model analysis will be carried out on same to find natural frequency’s (for comparison with other results)
Thermal analysis will be carried out on to find thermal characteristic.
Comparison tables will be prepared according to the obtained results from Ansys; Conclusion will be made according
to the obtained results.
Key words: steam turbine, shaft, hollow shaft,fatigue failure analysis.
*Corresponding Author:
D.Jojappa,
Research Scholar, Department of Mechanical Engineering,
Chebrolu engineering collage, Guntur, AP, India.
Email: darajojappa@gmail.com
Year of publication: 2016
Review Type: peer reviewed
Volume: III, Issue : I
Citation: D.Jojappa, Research Scholar, "Fatigue Failure Analysis
of Steam Turbine Shaft Using Fem Technique" International
Journal of Research and Innovation on Science, Engineering
and Technology (IJRISET) (2016) 194-198
It has almost completely replaced the reciprocating piston
steam engine primarily because of its greater thermal
efficiency and higher power-to-weight ratio. Because the
turbine generates rotary motion, it is particularly suited
to be used to drive an electrical generator – about 80% of
all electricity generation in the world is by use of steam
turbines. The steam turbine is a form of heat engine that
derives much of its improvement in thermodynamic efficiency
through the use of multiple stages in the expansion
of the steam, which results in a closer approach to
the ideal reversible process.
MODELS OF STEAM TURBINE SHAFT
INTRODUCTION OF STEAM TURBINE SHAFT
Turbine shaft is one of the main machine element where
high, intermediate and low pressure blades will be arranged
with the support of journal bearing. It has to bear
not only self, blades weight and also steam pressure, temperature
and torque.
Due to high fatigue lodes (continues cyclic load) caused
by above conditions shaft becomes weaker; mainly selfweight
is one of the big obstacle. If self-weight can be
reduced fatigue life can be improved and also mechanical
efficiency will be increased. Previous researcher’s has
done the research on materials only, in this thesis work
along with materials hollow shaft will be analysed.
The above image shows turbine shaft and bearings assembly
STEAM TURBINE:
A steam turbine is a mechanical device that extracts thermal
energy from pressurized steam, and converts it into
rotary motion. Its modern manifestation was invented by
Sir Charles Parsons in 1884.
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International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET)
The above image shows hallow shaft and bearings assembly
MATERIALS AND BOUNDARY CONDITIONS:
Weight= volume X density
Equivalent stress value, it is also called as vonmisses stress
which provides the average value of directional and principle
stress using vonmisses theory of failure.
THERMAL ANALYSIS FOR SOLID MODEL-MATERIAL1
Low pressure blade set= 4695903 X 0.00000785 Kg/mm 3
= 36.86
Intermediate pressure blade set= 2390470 X 0.00000785 Kg/
mm 3 = 18.76
High pressure blade set= 2163510 X 0.00000785 Kg/mm 3
= 16.98
Weight X newton’s = load
Low pressure blade set = 36.86 X 9.81=361.228
Intermediate pressure blade set = 18.76 X 9.81=184.142
High pressure blade set = 16.98 X 9.81=166.404
Load /area = pressure
Shaft Area of each blade set = 268535mm
Low pressure blade set = 0.0013
Intermediate pressure blade set = 0.000685
High pressure blade set = 0.000619
Total heat flux
FATIGUE ANALYSIS FOR SOLID MODEL-MATERIAL 1
Material 1
AISI 4130 Steel (super alloy steel) Material 1
Material 2
Haynes Hastelloy C-276 alloy
STRUCTURAL ANALYSIS FOR SOLID MODEL-MATE-
RIAL 1
Safety factor range on object
STRUCTURAL ANALYSIS FOR HALLOW MODEL-MA-
TERIAL 1
Total deformation
Equivalent stress
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International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET)
THERMAL ANALYSIS FOR HALLOW MODEL MATE-
RIAL 1
Total heat flux
FATIGUE ANALYSIS FOR HALLOW MODEL- MATERI-
AL 1
The above image shows hallow shaft, bearings and center support
bearing
STRUCTURAL ANALYSIS FOR HALLOW MODEL WITH
CENTER BEARING-MATERIAL 2
Maximum life
STRUCTURAL ANALYSIS FOR HALLOW MODEL-MA-
TERIAL 2
Equivalent stress value, it is also called as vonmisses stress
which provides the average value of directional and principle
stress using vonmisses theory of failure.
FATIGUE ANALYSIS FOR HALLOW MODEL WITH
CENTER BEARING-MATERIAL 2
Total deformation
RESULT TABLES
Safety factor range on object.
Equivalent stress
Materials AISI 4130
Steel
Total deformation
STRUCTURAL ANALYSIS
Solid shaft
C-276
alloy
AISI 4130
Steel
Hallow shaft
C-276
alloy
0.021188 0.02233 0.027235 0.026332
Stress 44.67 42.056 73.184 69.301
Strain 0.000221 0.000213 0.000437 0.000426
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International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET)
Materials AISI 4130
Steel
Temperature
THERMAL ANALYSIS
Solid shaft
C-276
alloy
AISI 4130
Steel
Hallow shaft
C-276
alloy
591.63 579.95 588.53 577.73
Heat flux 0.66966 0.42049 0.60857 0.38725
Thermal
error
Materials AISI 4130
Steel
Total deformation
HZ 1
Total deformation
HZ 2
Total deformation
HZ 3
Total deformation
HZ 4
Total deformation
HZ 5
Materials AISI 4130
Steel
7.4585e6 1.7605e6 4.7633e6 9.8352e5
MODEL ANALYSIS
Solid shaft
C-276
alloy
AISI 4130
Steel
Hallow shaft
C-276
alloy
144.92 143.39 168.41 166.42
145.18 143.65 177.22 175.15
418.62 413.79 372.42 368.31
419.11 414.27 382.68 378.51
709.51 695.61 475.99 470.09
FATIGUE ANALYSIS
Solid shaft
C-276
alloy
AISI 4130
Steel
Hallow shaft
C-276
alloy
LIFE 5e11 5e11 5e11 5e11
Damage 1.034 0.86538 3.7329 3.2395
HALLOW SHAFT WITH CENTER SUPPORT BEARING
TABLE
Materials
STRUCTURAL ANALYSIS
C-276 alloy
Total deformation 0.22403
Stress 65.783
Strain 0.00041147
Materials
THERMAL ANALYSIS
C-276 alloy
Temperature 577.73
Heat flux 0.38723
Thermal error 9.8352e5
Materials
MODEL ANALYSIS
C-276 alloy
Total deformation HZ 1 372.95
Total deformation HZ 2 383.67
Total deformation HZ 3 953.67
Total deformation HZ 4 975.5
Total deformation HZ 5 1190.4
Materials
LIFE
FATIGUE ANALYSIS
C-276 alloy
5e11
Damage 2.8291
CONCLUSION
This thesis work deals with “FATIGUE FAILURE ANAL-
YSIS OF STEAM TURBINE SHAFT USING FEM TECH-
NIQUE” to compare solid and hollow shafts; to suggest
best material and suitable location for the center bearing.
Structural, model, thermal and fatigue analysis is done
on solid and hollow shafts along with bearings by varying
materials; as per the analysis results hollow shaft is
having little bit high stress and deformation but these are
within the limit only while considering factor of safety.
Bearing was installed near high pressure blades for additional
support to use hollow shaft to reduce stress concentration;
then above analysis was conducted to evaluate
results.
As per the analysis work results hollow shaft with center
bearing and C-276 material will be the better option; using
these conditionsshaft weight can be reduced up to
51kgs [^16%] which interns increases the mechanical efficiency.
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International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET)
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Author
D.Jojappa,
Research Scholar, Department of Mechanical Engineering,
Chebrolu engineering college, Guntur, AP, India.
K.Naresh babu,
Assistant professor, Department of Mechanical Engineering,
Chebrolu engineering college, Guntur, AP, India.
K.krishnaveni,
Associate professor, Department of Mechanical Engineering,
Chebrolu engineering college, Guntur, AP, India.
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