fatigue failure analysis of steam turbine shaft using fem technique

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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.Jojappa1, K.Naresh babu2, K.krishnaveni3.

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.

*Corresponding Author:

D.Jojappa, Research Scholar, Department of Mechanical Engineering, Chebrolu engineering collage, Guntur, AP, India.Email: [email protected]

Year of publication: 2016Review Type: peer reviewedVolume: III, Issue : I

Citation: D.Jojappa, Research Scholar, "Fatigue Failure Analy-sis of Steam Turbine Shaft Using Fem Technique" International Journal of Research and Innovation on Science, Engineering and Technology (IJRISET) (2016) 194-198

INTRODUCTION OF STEAM TURBINE SHAFT

Turbine shaft is one of the main machine element where high, intermediate and low pressure blades will be ar-ranged with the support of journal bearing. It has to bear not only self, blades weight and also steam pressure, tem-perature and torque.

Due to high fatigue lodes (continues cyclic load) caused by above conditions shaft becomes weaker; mainly self-weight is one of the big obstacle. If self-weight can be reduced fatigue life can be improved and also mechani-cal 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.

STEAM TURBINE:

A steam turbine is a mechanical device that extracts ther-mal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884.

It has almost completely replaced the reciprocating pis-ton 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 ef-ficiency through the use of multiple stages in the expan-sion of the steam, which results in a closer approach to the ideal reversible process.

MODELS OF STEAM TURBINE SHAFT

The above image shows turbine shaft and bearings assembly

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.

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The above image shows hallow shaft and bearings assembly

MATERIALS AND BOUNDARY CONDITIONS:

Weight= volume X density

Low pressure blade set= 4695903 X 0.00000785 Kg/mm3 = 36.86Intermediate pressure blade set= 2390470 X 0.00000785 Kg/mm3 = 18.76High pressure blade set= 2163510 X 0.00000785 Kg/mm3 = 16.98

Weight X newton’s = load

Low pressure blade set = 36.86 X 9.81=361.228Intermediate pressure blade set = 18.76 X 9.81=184.142High pressure blade set = 16.98 X 9.81=166.404

Load /area = pressure

Shaft Area of each blade set = 268535mmLow pressure blade set = 0.0013Intermediate pressure blade set = 0.000685High pressure blade set = 0.000619

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

Total deformation

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

Total heat flux

FATIGUE ANALYSIS FOR SOLID MODEL-MATERIAL 1

Safety factor range on object

STRUCTURAL ANALYSIS FOR HALLOW MODEL-MA-TERIAL 1

Equivalent stress

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THERMAL ANALYSIS FOR HALLOW MODEL MATE-RIAL 1

Total heat flux

FATIGUE ANALYSIS FOR HALLOW MODEL- MATERI-AL 1

Maximum life

STRUCTURAL ANALYSIS FOR HALLOW MODEL-MA-TERIAL 2

Total deformation

Equivalent stress

The above image shows hallow shaft, bearings and center sup-port bearing

STRUCTURAL ANALYSIS FOR HALLOW MODEL WITH CENTER BEARING-MATERIAL 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

Safety factor range on object.

RESULT TABLES

STRUCTURAL ANALYSIS

Solid shaft Hallow shaft

Materials AISI 4130 Steel

C-276 alloy

AISI 4130 Steel

C-276 alloy

Total de-formation

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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THERMAL ANALYSIS



C-276 alloy

AISI 4130 Steel

C-276 alloy

Tempera-ture

591.63 579.95 588.53 577.73

Heat flux 0.66966 0.42049 0.60857 0.38725

Thermal error

7.4585e6 1.7605e6 4.7633e6 9.8352e5

MODEL ANALYSIS



C-276 alloy

AISI 4130 Steel

C-276 alloy

Total de-formation HZ 1

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



C-276 alloy

AISI 4130 Steel

C-276 alloy

LIFE 5e11 5e11 5e11 5e11

Damage 1.034 0.86538 3.7329 3.2395

HALLOW SHAFT WITH CENTER SUPPORT BEARING TABLE

STRUCTURAL ANALYSIS

Materials C-276 alloy

Total deformation 0.22403

Stress 65.783

Strain 0.00041147

THERMAL ANALYSIS


Temperature 577.73

Heat flux 0.38723

Thermal error 9.8352e5

MODEL ANALYSIS


Total deformation HZ 1 372.95





FATIGUE ANALYSIS


LIFE 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 vary-ing 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 ad-ditional support to use hollow shaft to reduce stress con-centration; then above analysis was conducted to evalu-ate results.

As per the analysis work results hollow shaft with center bearing and C-276 material will be the better option; us-ing these conditionsshaft weight can be reduced up to 51kgs [^16%] which interns increases the mechanical ef-ficiency.

REFERENCE

1.THERMAL STRESS ANALYSIS IN STEAM TURBINE RO-TOR - A REVIEW by Ms. Mohini R. Kolhe1, Prof. A. D. Pachchhao2, Prof. H.G.Nagpure3.

2.Calculation of Thermal Stress and Fatigue Life of 1000 MW Steam Turbine Rotor by ShuangBian, Wenyao Li.

3.DESIGN AND ANALYSIS OF STEAM TURBINE ROTOR byM. Chandra Sekhar Reddy.

4.Residual Life Assessment of 60 MW Steam Turbine Ro-tor by K. Venkatesh*, P. VeeraRaju**, T. Jayananda Ku-mar**

5.TRANSIENT THERMAL ANALYSIS OF A STEAM TUR-BINE ROTOR by Shilpa P. Bhorkar, Dr. A.V. Vanalkar.

6.ZvonimirGuzović, BranimirMatijašević, TihomirMihalić “Characteristics Of Non- Stationary Thermal Stresses In The Low-Pressure Part Of The Rotor”15th International Research/Expert Conference TMT-2011,Prague,Czech Republic 12-18 September 2011. 7.Chunlin Zhang, Niansu Hu, Jianmei Wang, Qiping,chen,FengHe,Xiaoli “ Thermal Stress Analysis for Rotor of 600MW Steam Turbine”978-1-4244-4813-5/10/&25.00c/2010/IEEE.

8.G SukhvinderKaurBhatti, ShyamalaKumari, M L Nee-lapu, C Kedarinath, Dr. I N Niranjan Kumar” Transient State Stress Analysis On An Axial Flow Gas Turbine Blades And Disk Using Finite Element Procedure”. in Int. Conf. on HEAT TRANSFER, THERMAL ENGINEERING and ENVIRONMENT, Elounda, Greece, August 21-23, 2006 (pp323-330).

9.Deepak Dhar, A. M. Sharan.” Transient Stress Analysis and Fatigue Life Estimation of Turbine Blades” Journal of Vibration and Acoustics OCTOBER 2004, Vol. 126 Õ 495.

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11.Sudheendra,V.S,SRamamurthKMurugesan”Transient,Thermal Analysis Of A Turbine Rotor”nal-ir.nal.res.in/8928 [7]Stuart R Holdsworth , EdoardoMazza&Arnd Jung” creep-fatigue damage developmentduring service-cycle thermo-mechanical fatigue test of 1CrMoV rotor steel”.

Author

D.Jojappa, Research Scholar, Department of Mechanical Engineer-ing, Chebrolu engineering college, Guntur, AP, India.

K.Naresh babu,Assistant professor, Department of Mechanical Engineer-ing, Chebrolu engineering college, Guntur, AP, India.

K.krishnaveni,Associate professor, Department of Mechanical Engineer-ing, Chebrolu engineering college, Guntur, AP, India.

fatigue failure analysis of steam turbine shaft using fem technique

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