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IRJET - Optimization of Crankshaft by Modification in Design and Material

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This document summarizes an analysis and optimization of a crankshaft design for a 4-cylinder inline gasoline engine. A 3D model of the crankshaft was created in Siemens NX software based on engine specifications. Finite element analysis was performed in ANSYS to evaluate stresses and deformation. The analysis showed maximum von Mises stress of 223.76 MPa and shear stress of 127.31 MPa, both at joints between the crankshaft spindle and web. Total deformation was a minimal 0.14091 mm. The safety factor of 1.5195 indicated the design would withstand fatigue loading over an infinite lifespan. Modifications like added fillets helped reduce stresses by distributing loads more evenly. The optimized

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International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 03 | Mar 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 3321 OPTIMIZATION OF CRANKSHAFT BY MODIFICATION IN DESIGN AND MATERIAL Aniket Dindore1, Ganesh Badiger2 1B.E Student, Department of Mechanical Engineering, SCOE, Pune, Maharashtra, India. 2B.E Student, Department of Mechanical Engineering, SCOE, Pune, Maharashtra, India. ---------------------------------------------------------------------***---------------------------------------------------------------------- Abstract – Crankshaft is an important component of the internal combustion engine. Due to huge loading and high number of fatigue cycles, crankshaft is prone to early damage and hence reducing the engine life. In this research paper, static structural analysis is performed on crankshaft for a 4- cylinder inline SI engine. A three- dimensional model of crankshaft is designed using SIEMENS NX 12.0 software. In order to study the effect of loading, Finite Element Analysis (FEA) is performed on ANSYS 18.1 software by applying load and constraints to the shaft according to engine working conditions. The analysis is performed for locating critical failure in crankshaft. The optimization includes the modification in the geometry of crankshaft which results in safe and efficient design of the crankshaft. The review of work on the crankshaft optimization and design is demonstrated. The materials, failure analysis, design parameters of the crankshaft analyzed here. Key Words: SI Engine, Crankshaft, Static Structural Analysis, Fatigue, ANSYS 18.1, SIEMENS NX 12.0, FEA. 1.INTRODUCTION Crankshaft is one of the key components in working of the internal combustion engine. It is moving component in the engine, which converts the reciprocating motion of the piston into a rotary motion. It consists ofshaftparts,journals bearings and a crankpin bearing. This study was conducted on a 4-cylinder inline SI engine so the crankshaft should have capacity to take the maximum downward force during power stroke without excessive bending. Because life and durability of IC engine depend on the strength of the crankshaft. As the engine start functioning, the impulses hit the crankshaft. For smooth functioning of the engine, crankshaft should be designed and optimized to provide efficient working of engine. The geometry of a crankshaft is complicated, and function of itsrotational positionthevaries load. Because of the dissimilar area of cross-sections of the crankshaft, it will be more dangerous to continue because the stiffness discontinuities will be causing maximum stress concentration. Mostly, the crankshaft fillet will be the highly stressed area and will require accuracyasthematerialsused to make crankshafts are typically sensitive to notch factors. In this research the fillet medicationandthe material used in the crankshaft will provide more safety to the engine, considering the results obtained by optimizing the crankshaft shows the safe and efficient working with the increase in the life of crankshaft. In the static structural analysis, the stress concentration of the crankshaft is described by Xiaorong Zhou et al. [1]. In the fillet of spindle neck the stress is mostly occurred and there is high stress at crankpin fillet. On the basis of stress analysis, the maximum strength can be achieved as per requirement. In this paper the analysis is carried out to obtainthemaximumstrengthof crankshaft. C.M. Balamurugan et.al [2] had designed the model in SOLID EDGE and further done analysis in ANSYS. In their paper comparison with two different material i.e. ductile cast iron and forged steel which increases the fatigue life. The optimization included geometry change with the current engine, fillet rolling which deducted the cost of the crankshaft. Analysis results obtained while the crankshaft subjected under static load having stresses and deformation. J. Meng et.al [3] in their research paper designed crankshaft model in Pro-E software andanalysis done in the ANSYS.The difference between the frequency and vibration modal is described by FEA analysis. This analysis resulted in theoretical foundation for optimization of engine design and by appropriatedesigntheresonancevibrationcanbeavoided and safety can be increased. R. J. Deshbhratar et.al [4] have designed crankshaft by using Pro-E and analysis was done by ANSYS software. The maximum stress is seen in the fillet area and also around the center of crank pin. At most of the times crankshaft deforms because of bending under naturalfrequencyasthemaximum deformation is observed on crankpin neck. Rinkle garg et.al [5] in their paperoncrankshaftmodelwhich was designed in Pro-Esoftware and used ANSYSsoftwarefor simulation. It states that increase in strength of crankshaft reduces the maximum stress, strain and deformation. Which makes the engine more efficient in the working and the cost effective. In the literature survey Mahesh L. Raotole et.al [6] have researched the life duration of crankshaft using FEA. They created modelusingMATLABandusedANSYSforsimulation. By carrying out dynamic analysisatvariousenginespeedand at fillet radius, conclusion was that the crankshaft failure occurs in fillet region. So, designer should take into consideration that the fatiguelifeas most importantfactorof design. K. Thriveni et.al [7] have performed static analysis on 4- stroke IC engine. Using CATIA modelling was done and analysis performed in ANSYS. They observed that maximum stress and deformation is at the neck of crankpin.Andmostly

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International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 03 | Mar 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 3322 maximum stress is developed at the fillet area.In all the literature review fatiguelifeisconsideredasimportantfactor of design hence in this paperoptimizationismadetoincrease the life and safety of component. 2. DESIGN FOR CRANKSHAFT 2.1 Material Selection AISI 4140 cold worked steel also known as 42Cr4Mo2 (EN 19) steel. AISI 4140 is known as chromium-molybdenum alloy steel. Chromium provides good hardness, where the molybdenum has uniform hardness and good strength. The properties of AISI 4140 consist of high toughness, wear resistance and good ductility in the quenched condition and tempered condition. The AISI 4140 cold finished annealed alloy steel can be heated using different methods to obtain a various property, hence it is mostly used for forgingbecause of its self-scaling properties. Crankshafts needmorestrength and stiffness to carry the loads in modern engines. Thus, the cold worked forged steel crankshafts offer higher strength and stiffness and the other material characteristics than the cast iron alternative. 2.2 Chemical Composition of Crankshaft The material selected for crankshaft is AISI 4140 cold worked steel also known as 42Cr4Mo2 (EN 19) steel. The detailed composition of material is as below mentioned in Table 1 Table -1: Chemical Composition Content Percentage C 0.35 - 0.45 Mn 0.5 - 0.8 Si 0.10 - 0.35 Ni 0 - 0.02 Mechanical Properties: Hardness: BHN = 241 HRC: 22 Yield tensile strength: 485 MPa Ultimate Tensile strength: 814 MPa Elongation at breaking: 22.2 %. 2.3 Design Parameters Assumed Below given specification in TABLE II used to design the crankshaft. Thespecifications are basedonHondaCity(2015 sedan). Table -2: Vehicle Specification Type 4-cylinder inline SI engine Bore 73 mm Stroke 89.4 mm Net displacement ratio 1497 cc Torque 145 Nm @ 4600 rpm 2.4 Design Procedure Considering the chemical composition, design of the crankshaft is performed using theoretical calculations. The crankshaft design is made by considering following such as the position of crank. When the crank is having maximum bending moment, when the crank angle is at which twisting moment is maximum. a) When Crank Is at the Dead Center. At this point, the bending of shaft caused due to transmitted maximum force on crankpin in plane of crank by maximum gas pressure load of piston. The crankpin ends of the crankshaft will only be subjected to bending moment. Thus, when crank is at dead center, the twisting moment is negligible and the bending moment ismaximum.Thevarious forces that are acting on the crankshaft are indicated as below Fig 1 Fig 1: Crankshaft at dead Centre Let, d = Piston diameter (mm), p = Maximum intensity of pressure N/mm2 we know gas load on piston Fp = Area of bore x Max. Combustion pressure = π/4 x d2 x Pmax (Where Pmax = 65 bar = 6.5N/mm2) Fp = 27.2 kN Since, crankshaft is symmetrical and inline so force on bearing shaft, R1 =R2 = FP /2 = 13.6kN b = 2D = 2 x 73 = 146 mm b1 = b2 = b/2 = 73mm

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International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 03 | Mar 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 3323 b) Design of Crank Pin Crankpin issubjected to shearstressduetotwistingmoment. Therefore, we are able to calculate the bending moment at center of crankpin and also twisting moment on crank pin . Let, dc = Crank pin Diameter (mm) Lc = Crank pin Length (mm) σallow = Allowable bearing stress = 841 Mpa Bending moment at the centre of crank pin is, Mb = R1 x b1 = 992.982 Nm We know that Mb = π/32 x (dc)2 x σb /FOS dc = 35 mm Now, the length of crank pin lc = Fp / (dc x Pb) = 25 mm c) Design of Crank Web The crank web is designed for eccentric loading. There are two stresses on the crank web, i.e. direct compressive stress and the bending stress. w is width of crank web; t is thickness of web from design data handbook t = 0.45 x dc + 6.35 = 22.5 = say 25 mm Also, width of crank web is, w = 1.125 x dc +12.7 = 76mm = say 84 mm Lw = 150mm (from design data handbook) Right and Left side of web will have same dimensions due to symmetry of loading. d) Stresses Induced (von mises) According to theory of distortion energy, the Von-Misses stress in the crank-pin is, Mev = √ ((Kb x Mo)2+3/ (4) x (Kt x To)2) Where, Kb = 2 (combined shock and fatigue factor for bending) and Kt = 1.5 (shock and fatigue factor for torsion) Mev = π/32 x (dc)3 x σv σv = 230.73 MPa Tev = π/16 x (dc)3 x τ τ = 137.69 MPa 3. DESIGN METHODOLOGY 3.1 Procedure of static Analysis Modelling of crankshaft was performed in Siemens NX12.0. According to the calculated dimensions from the theoretical steps, the crankshaft was modelled. Fillet of 5mm was provided at the joints of the spindle and web for even stress – strain distribution. Fig -2: Crankshaft geometry 3.2 Pre- processing details Before performing analysis on solver, it is necessary to pre process the model to get precise and authentic results. Since the geometry does not have highly complicated structures, hence a geometry cleans up was not conducted. Meshing is an important parameter which decides the quality of results obtained Meshing of Crankshaft Type of element: - Quadrilateral Dominant Order of element: - Quadratic Number of nodes: - 158272 Number of elements: - 46661 Quadrilateral dominant elements areselectedbecauseofthe skewness offered. Since quadrilateral elements offer proper deformation under substantial loading, these elements are used in meshing to obtain proper results. Fig -3: Meshed Model

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International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 03 | Mar 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 3324 3.3 Boundary conditions and load Frictionless support is provided to the crankshaft according to the engine working condition. During power stroke, combustion take place in combustionchamberwhichcauses crankshaft to rotate. The force is transferred from connecting rod to crankpin and load of 30000 N acting on crankshaft is shown in Fig. 4 Fig -4: Loads on crankshaft 4. Results and Discussion On applying boundary conditions and loads on the pre- processed model, following results were obtained. Fig -5: Von mises stress Fig. 5 shows Von Mises Stress occurring in the crankshaft. It is observed that maximum amount of shear stress is at the spindle and web joint which is 223.76 MPa. Fig -6: Shear stress In Fig 6, shear stress occurring in the crankshaft is reduced. In this case too, it is observed that maximum shear stress is occurring at joints between spindle and the crank web and it is found out to be 127.31 MPa. Fig -7: Total Deformation Fig 7 represents the total deformation occurring in the crankshaft under the given maximum loading. The deformation occurring is very minimum and occursbetween the central spindle joining the intermediate webs. The maximum deformation is 0.14091 mm. Fig -8: Factor of safety Fig 8 depicts the Factor of Safety (FOS) obtained in the crankshaft under fatigue loading. Since reverse cyclic loads are imposed on crankshaft, it is importanttocalculatefatigue strength of crankshaft. The FOS calculated is for infinite life cycles and is found out to be 1.5195. The least value of FOS defines the total FOS of the component. Table -3: RESULT TABLE Stresses Theoretical (MPa ) FEA (MPa ) Von mises 230.73 223.76 shear 137.69 127.31 The comparison between the theoretical and FEA results clearly state that the stress obtained are very close and the optimization result in the less stress to developed and the property of material induces less shear stress. Due to thisthe working become more efficient and the safety of machine is thus increased. 5. CONCLUSIONS The Von mises stress in the crankshaft is far more less than that of yield stress of the material. Shear stress in the crankpin is also within permissible limits. Thus, it can be concluded that design of crankshaft considered to be safe under the loading conditions. Deformation of the crankshaft is 0.15 mm which is too negligible in rotating motion of the crankshaft. Since the deformation is negligible, crankshaft leads to smooth

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International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 03 | Mar 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 3325 running and increasing the engine life expectancyand better power delivery. Due to fillets at the end of crankpin and thecrank web,stress is evenly distributed which leads tolessstressconcentration at the joints. Hence providing fillet will lead to a safer design than that of without fillet joining. The Safety Factor (FOS) is found to be 1.5, which results in assurance of safety of the crankshaft in cases of uneven and more loading than that of ideal loading. REFERENCES [1] Xiaorong Zhou., Ganwei Cai., Zhuan Zhang. Zhongqing Cheng., “Analysis on Dynamic Characteristics of Internal Combustion Engine Crankshaft System,” International Conference on Measuring Technology and Mechatronics Automation. 2009. [2] C.M Balamurugan, R. Krishnaraj, Dr.M.Sakhivel, K.kanthavel, Deepan Marudachalam M. G. R.Palani, “Computer Aided modelling and optimization of Crankshaft”, International Journal of scientific and Engineering Research, Vol-2, issue-8, ISSN:2229- 5518,2011. [3] J. Meng, Y. Liu, R. Liu, “Finite Element analysis of 4- Cylinder Diesel Crankshaft” I.J. Image, Graphics and Signal Processing, volume-5, 2011. [4] R.J Deshbhratar, Y.R Suple, “Analysis and optimization of Crankshaft using FEM”, International Journal of Modern Engineering Research, volume-2,issue-5,ISSN:2249-6645,2012. [5] Rinkle Garg, Sunil Baghla, “Finite element analysis and optimization of crankshaft”, International Journal of Engineering and Management Research, vol-2, Issue-6, ISSN: 2250-0758, 2012. [6] Mahesh L. Raotole, Prof. D. B. Sadaphale, Prof. J. R. Chaudhari, Prediction of Fatigue Life of Crank Shaft using S-N Approach International Journal of Emerging Technology and Advanced Engineering, ISSN 2250-2459, Volume 3, Issue 2, 2013. [7] K. Thriveni, Dr. B. JayaChandraiah, “Modelling and Analysis of the Crankshaft Using Ansys Software”, International Journal of Computational Engineering Research, Volume-3, Issue-5, 2013.

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IRJET - Optimization of Crankshaft by Modification in Design and Material

  • 1. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 03 | Mar 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 3321 OPTIMIZATION OF CRANKSHAFT BY MODIFICATION IN DESIGN AND MATERIAL Aniket Dindore1, Ganesh Badiger2 1B.E Student, Department of Mechanical Engineering, SCOE, Pune, Maharashtra, India. 2B.E Student, Department of Mechanical Engineering, SCOE, Pune, Maharashtra, India. ---------------------------------------------------------------------***---------------------------------------------------------------------- Abstract – Crankshaft is an important component of the internal combustion engine. Due to huge loading and high number of fatigue cycles, crankshaft is prone to early damage and hence reducing the engine life. In this research paper, static structural analysis is performed on crankshaft for a 4- cylinder inline SI engine. A three- dimensional model of crankshaft is designed using SIEMENS NX 12.0 software. In order to study the effect of loading, Finite Element Analysis (FEA) is performed on ANSYS 18.1 software by applying load and constraints to the shaft according to engine working conditions. The analysis is performed for locating critical failure in crankshaft. The optimization includes the modification in the geometry of crankshaft which results in safe and efficient design of the crankshaft. The review of work on the crankshaft optimization and design is demonstrated. The materials, failure analysis, design parameters of the crankshaft analyzed here. Key Words: SI Engine, Crankshaft, Static Structural Analysis, Fatigue, ANSYS 18.1, SIEMENS NX 12.0, FEA. 1.INTRODUCTION Crankshaft is one of the key components in working of the internal combustion engine. It is moving component in the engine, which converts the reciprocating motion of the piston into a rotary motion. It consists ofshaftparts,journals bearings and a crankpin bearing. This study was conducted on a 4-cylinder inline SI engine so the crankshaft should have capacity to take the maximum downward force during power stroke without excessive bending. Because life and durability of IC engine depend on the strength of the crankshaft. As the engine start functioning, the impulses hit the crankshaft. For smooth functioning of the engine, crankshaft should be designed and optimized to provide efficient working of engine. The geometry of a crankshaft is complicated, and function of itsrotational positionthevaries load. Because of the dissimilar area of cross-sections of the crankshaft, it will be more dangerous to continue because the stiffness discontinuities will be causing maximum stress concentration. Mostly, the crankshaft fillet will be the highly stressed area and will require accuracyasthematerialsused to make crankshafts are typically sensitive to notch factors. In this research the fillet medicationandthe material used in the crankshaft will provide more safety to the engine, considering the results obtained by optimizing the crankshaft shows the safe and efficient working with the increase in the life of crankshaft. In the static structural analysis, the stress concentration of the crankshaft is described by Xiaorong Zhou et al. [1]. In the fillet of spindle neck the stress is mostly occurred and there is high stress at crankpin fillet. On the basis of stress analysis, the maximum strength can be achieved as per requirement. In this paper the analysis is carried out to obtainthemaximumstrengthof crankshaft. C.M. Balamurugan et.al [2] had designed the model in SOLID EDGE and further done analysis in ANSYS. In their paper comparison with two different material i.e. ductile cast iron and forged steel which increases the fatigue life. The optimization included geometry change with the current engine, fillet rolling which deducted the cost of the crankshaft. Analysis results obtained while the crankshaft subjected under static load having stresses and deformation. J. Meng et.al [3] in their research paper designed crankshaft model in Pro-E software andanalysis done in the ANSYS.The difference between the frequency and vibration modal is described by FEA analysis. This analysis resulted in theoretical foundation for optimization of engine design and by appropriatedesigntheresonancevibrationcanbeavoided and safety can be increased. R. J. Deshbhratar et.al [4] have designed crankshaft by using Pro-E and analysis was done by ANSYS software. The maximum stress is seen in the fillet area and also around the center of crank pin. At most of the times crankshaft deforms because of bending under naturalfrequencyasthemaximum deformation is observed on crankpin neck. Rinkle garg et.al [5] in their paperoncrankshaftmodelwhich was designed in Pro-Esoftware and used ANSYSsoftwarefor simulation. It states that increase in strength of crankshaft reduces the maximum stress, strain and deformation. Which makes the engine more efficient in the working and the cost effective. In the literature survey Mahesh L. Raotole et.al [6] have researched the life duration of crankshaft using FEA. They created modelusingMATLABandusedANSYSforsimulation. By carrying out dynamic analysisatvariousenginespeedand at fillet radius, conclusion was that the crankshaft failure occurs in fillet region. So, designer should take into consideration that the fatiguelifeas most importantfactorof design. K. Thriveni et.al [7] have performed static analysis on 4- stroke IC engine. Using CATIA modelling was done and analysis performed in ANSYS. They observed that maximum stress and deformation is at the neck of crankpin.Andmostly
  • 2. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 03 | Mar 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 3322 maximum stress is developed at the fillet area.In all the literature review fatiguelifeisconsideredasimportantfactor of design hence in this paperoptimizationismadetoincrease the life and safety of component. 2. DESIGN FOR CRANKSHAFT 2.1 Material Selection AISI 4140 cold worked steel also known as 42Cr4Mo2 (EN 19) steel. AISI 4140 is known as chromium-molybdenum alloy steel. Chromium provides good hardness, where the molybdenum has uniform hardness and good strength. The properties of AISI 4140 consist of high toughness, wear resistance and good ductility in the quenched condition and tempered condition. The AISI 4140 cold finished annealed alloy steel can be heated using different methods to obtain a various property, hence it is mostly used for forgingbecause of its self-scaling properties. Crankshafts needmorestrength and stiffness to carry the loads in modern engines. Thus, the cold worked forged steel crankshafts offer higher strength and stiffness and the other material characteristics than the cast iron alternative. 2.2 Chemical Composition of Crankshaft The material selected for crankshaft is AISI 4140 cold worked steel also known as 42Cr4Mo2 (EN 19) steel. The detailed composition of material is as below mentioned in Table 1 Table -1: Chemical Composition Content Percentage C 0.35 - 0.45 Mn 0.5 - 0.8 Si 0.10 - 0.35 Ni 0 - 0.02 Mechanical Properties: Hardness: BHN = 241 HRC: 22 Yield tensile strength: 485 MPa Ultimate Tensile strength: 814 MPa Elongation at breaking: 22.2 %. 2.3 Design Parameters Assumed Below given specification in TABLE II used to design the crankshaft. Thespecifications are basedonHondaCity(2015 sedan). Table -2: Vehicle Specification Type 4-cylinder inline SI engine Bore 73 mm Stroke 89.4 mm Net displacement ratio 1497 cc Torque 145 Nm @ 4600 rpm 2.4 Design Procedure Considering the chemical composition, design of the crankshaft is performed using theoretical calculations. The crankshaft design is made by considering following such as the position of crank. When the crank is having maximum bending moment, when the crank angle is at which twisting moment is maximum. a) When Crank Is at the Dead Center. At this point, the bending of shaft caused due to transmitted maximum force on crankpin in plane of crank by maximum gas pressure load of piston. The crankpin ends of the crankshaft will only be subjected to bending moment. Thus, when crank is at dead center, the twisting moment is negligible and the bending moment ismaximum.Thevarious forces that are acting on the crankshaft are indicated as below Fig 1 Fig 1: Crankshaft at dead Centre Let, d = Piston diameter (mm), p = Maximum intensity of pressure N/mm2 we know gas load on piston Fp = Area of bore x Max. Combustion pressure = π/4 x d2 x Pmax (Where Pmax = 65 bar = 6.5N/mm2) Fp = 27.2 kN Since, crankshaft is symmetrical and inline so force on bearing shaft, R1 =R2 = FP /2 = 13.6kN b = 2D = 2 x 73 = 146 mm b1 = b2 = b/2 = 73mm
  • 3. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 03 | Mar 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 3323 b) Design of Crank Pin Crankpin issubjected to shearstressduetotwistingmoment. Therefore, we are able to calculate the bending moment at center of crankpin and also twisting moment on crank pin . Let, dc = Crank pin Diameter (mm) Lc = Crank pin Length (mm) σallow = Allowable bearing stress = 841 Mpa Bending moment at the centre of crank pin is, Mb = R1 x b1 = 992.982 Nm We know that Mb = π/32 x (dc)2 x σb /FOS dc = 35 mm Now, the length of crank pin lc = Fp / (dc x Pb) = 25 mm c) Design of Crank Web The crank web is designed for eccentric loading. There are two stresses on the crank web, i.e. direct compressive stress and the bending stress. w is width of crank web; t is thickness of web from design data handbook t = 0.45 x dc + 6.35 = 22.5 = say 25 mm Also, width of crank web is, w = 1.125 x dc +12.7 = 76mm = say 84 mm Lw = 150mm (from design data handbook) Right and Left side of web will have same dimensions due to symmetry of loading. d) Stresses Induced (von mises) According to theory of distortion energy, the Von-Misses stress in the crank-pin is, Mev = √ ((Kb x Mo)2+3/ (4) x (Kt x To)2) Where, Kb = 2 (combined shock and fatigue factor for bending) and Kt = 1.5 (shock and fatigue factor for torsion) Mev = π/32 x (dc)3 x σv σv = 230.73 MPa Tev = π/16 x (dc)3 x τ τ = 137.69 MPa 3. DESIGN METHODOLOGY 3.1 Procedure of static Analysis Modelling of crankshaft was performed in Siemens NX12.0. According to the calculated dimensions from the theoretical steps, the crankshaft was modelled. Fillet of 5mm was provided at the joints of the spindle and web for even stress – strain distribution. Fig -2: Crankshaft geometry 3.2 Pre- processing details Before performing analysis on solver, it is necessary to pre process the model to get precise and authentic results. Since the geometry does not have highly complicated structures, hence a geometry cleans up was not conducted. Meshing is an important parameter which decides the quality of results obtained Meshing of Crankshaft Type of element: - Quadrilateral Dominant Order of element: - Quadratic Number of nodes: - 158272 Number of elements: - 46661 Quadrilateral dominant elements areselectedbecauseofthe skewness offered. Since quadrilateral elements offer proper deformation under substantial loading, these elements are used in meshing to obtain proper results. Fig -3: Meshed Model
  • 4. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 03 | Mar 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 3324 3.3 Boundary conditions and load Frictionless support is provided to the crankshaft according to the engine working condition. During power stroke, combustion take place in combustionchamberwhichcauses crankshaft to rotate. The force is transferred from connecting rod to crankpin and load of 30000 N acting on crankshaft is shown in Fig. 4 Fig -4: Loads on crankshaft 4. Results and Discussion On applying boundary conditions and loads on the pre- processed model, following results were obtained. Fig -5: Von mises stress Fig. 5 shows Von Mises Stress occurring in the crankshaft. It is observed that maximum amount of shear stress is at the spindle and web joint which is 223.76 MPa. Fig -6: Shear stress In Fig 6, shear stress occurring in the crankshaft is reduced. In this case too, it is observed that maximum shear stress is occurring at joints between spindle and the crank web and it is found out to be 127.31 MPa. Fig -7: Total Deformation Fig 7 represents the total deformation occurring in the crankshaft under the given maximum loading. The deformation occurring is very minimum and occursbetween the central spindle joining the intermediate webs. The maximum deformation is 0.14091 mm. Fig -8: Factor of safety Fig 8 depicts the Factor of Safety (FOS) obtained in the crankshaft under fatigue loading. Since reverse cyclic loads are imposed on crankshaft, it is importanttocalculatefatigue strength of crankshaft. The FOS calculated is for infinite life cycles and is found out to be 1.5195. The least value of FOS defines the total FOS of the component. Table -3: RESULT TABLE Stresses Theoretical (MPa ) FEA (MPa ) Von mises 230.73 223.76 shear 137.69 127.31 The comparison between the theoretical and FEA results clearly state that the stress obtained are very close and the optimization result in the less stress to developed and the property of material induces less shear stress. Due to thisthe working become more efficient and the safety of machine is thus increased. 5. CONCLUSIONS The Von mises stress in the crankshaft is far more less than that of yield stress of the material. Shear stress in the crankpin is also within permissible limits. Thus, it can be concluded that design of crankshaft considered to be safe under the loading conditions. Deformation of the crankshaft is 0.15 mm which is too negligible in rotating motion of the crankshaft. Since the deformation is negligible, crankshaft leads to smooth
  • 5. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 03 | Mar 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 3325 running and increasing the engine life expectancyand better power delivery. Due to fillets at the end of crankpin and thecrank web,stress is evenly distributed which leads tolessstressconcentration at the joints. Hence providing fillet will lead to a safer design than that of without fillet joining. The Safety Factor (FOS) is found to be 1.5, which results in assurance of safety of the crankshaft in cases of uneven and more loading than that of ideal loading. REFERENCES [1] Xiaorong Zhou., Ganwei Cai., Zhuan Zhang. Zhongqing Cheng., “Analysis on Dynamic Characteristics of Internal Combustion Engine Crankshaft System,” International Conference on Measuring Technology and Mechatronics Automation. 2009. [2] C.M Balamurugan, R. Krishnaraj, Dr.M.Sakhivel, K.kanthavel, Deepan Marudachalam M. G. R.Palani, “Computer Aided modelling and optimization of Crankshaft”, International Journal of scientific and Engineering Research, Vol-2, issue-8, ISSN:2229- 5518,2011. [3] J. Meng, Y. Liu, R. Liu, “Finite Element analysis of 4- Cylinder Diesel Crankshaft” I.J. Image, Graphics and Signal Processing, volume-5, 2011. [4] R.J Deshbhratar, Y.R Suple, “Analysis and optimization of Crankshaft using FEM”, International Journal of Modern Engineering Research, volume-2,issue-5,ISSN:2249-6645,2012. [5] Rinkle Garg, Sunil Baghla, “Finite element analysis and optimization of crankshaft”, International Journal of Engineering and Management Research, vol-2, Issue-6, ISSN: 2250-0758, 2012. [6] Mahesh L. Raotole, Prof. D. B. Sadaphale, Prof. J. R. Chaudhari, Prediction of Fatigue Life of Crank Shaft using S-N Approach International Journal of Emerging Technology and Advanced Engineering, ISSN 2250-2459, Volume 3, Issue 2, 2013. [7] K. Thriveni, Dr. B. JayaChandraiah, “Modelling and Analysis of the Crankshaft Using Ansys Software”, International Journal of Computational Engineering Research, Volume-3, Issue-5, 2013.