Optimization of connecting rod

VSRD International Journal of Electrical, Electronics & Communication Engineering, Vol. III Issue XII December 2013 e-ISSN : 2231-3346, p-ISSN : 2319-2232 © VSRD International Journals : www.vsrdjournals.com

/ 407

RESEARCH ARTICLE

OPTIMIZATION OF CONNECTING ROD BY USING NON-LINEAR STATIC FINITE ELEMENT ANALYSIS 1Ajit

Kumar Senapati* and 2Gopal Krushna Mohanta

1Associate

Professor, 2Assistant Professor, 1,2Department of Mechanical Engineering Gandhi Institute of Engineering &Technology, Gunupur, Odisha, INDIA. *Corresponding Author : [email protected]

ABSTRACT This paper deals with nonlinear static analysis and optimization of forged steel connecting rod. Optimization is important as less time is required to produce the connecting rod which is stronger, lighter with minimum cost. In this article connecting rod material is replaced by Aluminium reinforced with Boron carbide for motorbike. A 2D drawing is drafted from the calculations. A parametric model of connecting rod is modeled using HYPERMESH 4.0 software. Analysis is carried out by using RADIOSYS software. Finite element analysis of connecting rod is done by considering two materials, viz. Aluminium Reinforced with Boron Carbide and Aluminium 360. The best combination of parameters like Von misses stress and strain, Deformation, Factor of safety and weight reduction for two wheeler connecting rod were done in RADIOSYS software. The design and weight of the connecting rod influence the engine performance. Specifications of connecting rod have been evaluated to calculate the loads acting on it. Structural analysis is carried out on piston end and crank end of connecting rod then further study was conducted to explore weight reduction opportunities for a production of connecting rod. The component is to be optimized for weight subject to constraint of allowable stress and factor of safety. The percentage weight reduction obtained was 7.35% by optimization. Connecting rod, Static analysis, Carbon steel. Keywords : FEA; Static; Aluminium; Aluminium reinforced with Boron carbide; Aluminium 360; Connecting Rod; Optimization; etc.

1. INTRODUCTION Automobile components are in great demand these days because of increased use of automobiles. The increased demand is due to improved performance and reduced cost of these components. R&D and Test engineers should develop critical components in shortest possible time to minimize launch time for new products. This necessitates understanding of new technologies and quick absorption in the development of newer products. Connecting rod is highly dynamically loaded component used for power transmission in combustion engines. It is considered as key component in terms of structural durability and efficiency. It acts as an intermediate link between the piston and crankshaft of I.C engine. Its basic function is to transmit thrust from piston to crankshaft. Connecting rods are subjected to forces generated by mass and fuel combustion. These two forces results in axial and bending stresses. Bending stresses appear due to eccentricities, crankshaft, case wall deformation, and rotational mass force. Therefore, a connecting rod must be capable of transmitting axial tension, axial compression, and bending stresses caused by the thrust and pull on the piston and by centrifugal force. FEA has evolved powerful tool supporting engineers in various fields of product development and research with continuous increasing computational capabilities. Webster et al. [1] was first to carry out three dimensional FEA of high speed diesel engine connecting rod. X. Hou et al. [2] carried out sensitivity analysis and optimization based on the combination in design of the connecting rod of LJ276M electronic gasoline engine. T.H. Lee et al. [3], proposed meta model based shape optimization of

connecting rod considering fatigue life. Meta model based design optimization of connecting rod can reduce the actual cost of computer simulations compared with that of classical design optimization. P. Charkha et al. [4], carried out analysis and optimization of forged steel connecting rod. The structural improvement of diesel engine connecting rod was carried by Z. Bin et al.[5], showed that the exposed destructive position is the transition location of small end and connecting rod shank at maximum compression condition. Z. Bin et al [6],. presented the design connecting rod of internal combustion engine using the topology optimization with objectives to develop structural modeling, FEA and the optimization of the connecting rod. M.S. Shaari et al. [7], investigated that with fully reverse loading, one can estimate longevity of a connecting rod and also find the critical points from where there is possibility of crack growth initiation in the connecting rod of universal tractor (U650). M. Omid et al [8], introduced a method of the connecting rod structural. The thermal deformation and mechanical deformation will cause connecting rod cracks, tortuosity, etc. Therefore, it is essential to analyze the stress field, temperature field, heat transfer, thermal load and mechanical load coupling of connecting rod in order to lower the heat load and improve the thermal stress distribution and improve its working reliability during the connecting rod designed. Analysis method of the finite element provides a powerful calculation tool, which is better than test method and theory analysis method and has become an important means for internal combustion engine performance study. Connecting rods are widely used variety of engine. The function of connecting rod is to transmit the thrust of the

Ajit Kumar Senapati and Gopal Krushna Mohanta

piston to the crank shaft, and as the result the reciprocating motion of the piston is translated into rotational motion of the crank shaft. It consist of a pin – end. A shank section, and crank an end .Pin end and crank end pin holes are machined to permit accurate fitting of bearings. One end of the connecting rod is connected to the piston by the piston pin. Connecting rods are subjected to forces generated by mass and fuel combustion .Theses two forces results in axial load and bending stresses. A connecting rod must be capable of transmitting axial tension, axial compression, and bending stress caused by the thrust and full of the piston and by centrifugal force. Finite element (FEM) Model is a modern way for fatigue analysis and estimation of the component .The influential component factors are able to change such as material .cross section conditions etc. In modern automotive internal combustion engine, the connecting rods are most usually made of steel for production engine. But can be made of aluminium or titanium for high performance of engines of cast iron for application such as motor scooters. They are not rigidly fixed at either end , so that the angle between the connecting rod and piston can change as the rod moves up and down and rotates around the crank shaft .The big end connects to the bearings journal on the throw connecting rod is under tremendous stress from the reciprocating load represented by the piston ,actually stretching and being compressed with every rotation, and the load increases to the third power with increasing engine speed .Connecting rod for automotive applications are typically manufactured by forging from either wrought steel or powder metal. Schematic diagram for connecting rod as shown in figure 1. 2. SPECIFICATION OF THE PROBLEM The objective of the present work is to design and analysis of connecting rod made of Aluminum Reinforced with Boron carbide. Steel and aluminum materials are used to design the connecting rod. In this project the material (carbon steel) of connecting rod replaced with Aluminum Reinforced with Boron carbide. Connecting rod was phase variable sinusoidal voltage waveforms by modulating the on and off times of the power switches. In industrial drive applications, the PWM inverter operates as a three-phase variablefrequency, variable-voltage source with fundamental frequency varying from zero to three times the motor nominal frequency. In some control schemes where a three-phase, variable-frequency current source is required, current control loops are added to force the motor currents to follow an input reference (usually sinusoidal) created in Pro-E. Model is imported in ANSYS 12.0 for analysis. After analysis a comparison is made between existing steel and aluminum connecting rod viz., Aluminum Reinforced with Boron carbide in terms of weight, factor of safety, stiffness, deformation and stress. 3. EXISTING METHODS A. Steps in Modeling of Connecting Rod : Optimized

VSRDIJEECE, Vol. III (XII) December 2013 / 408

Connecting Rod has been modeled with the help of PRO/E Wildfire 4.0 software. The Orthographic and Solid Model of optimized connecting rod is shown in figures below :

Fig.1: Drawing of Connecting Rod (Optimized)

Fig.2: CAD Model of Connecting Rod in HYPERMESH The following is the list of steps that are used to create the required model: a. Choose the reference plane. b. Set the dimension in mm. c. Go to sketcher and sketch circular entities. d. Then extrude these entities for making the both ends of connecting rod. e. Again reference plane is selected for shank of connecting rod. f. Entities is made that should be tangential to both ends. g. Extrude the entities symmetrically. h. Plane is selected for making entities of groove. i. Groove is made on the shank and mirrored for creating groove on both side. j. Datum plane is selected for creating small holes on piston end k. Then holes are made on the periphery of piston end. B. Specification of Existing Connecting Rod : Table 1 shows the specifications of the connecting rod for carbon steel (Suzuki GS). The typical chemical composition of the material is 0.61%C, 0.095% Al, 0.82%Mn, 0.00097%Br, 0.145% C, 7.8Co, 75.56Fe and 3.25 Mo.

Ajit Kumar Senapati and Gopal Krushna Mohanta

S.L 1 2 3

VSRDIJEECE, Vol. III (XII) December 2013 / 409

Table 1 : Specifications of Connecting Rod Parameters Value Bore × Stroke (mm) 57×58.6 Length of 112 mm connecting rod Thickness of For C.S = 3.2mm For AL connecting rod 360 = 4.1 mm

4

Width of connecting rod

For C.S = 12.8mm For AL 360 = 16.4 mm

5

Height of connecting rod

For C.S H1 =12mm H2 =17.6mm For C.S H1 =12mm H2 =17.6mm

C. Structural Analysis of Connecting Rod : Dimensions of Width and height of the connecting rod is For C.S = 12.8mm and For AL 360 = 16.4 mm. A 3-D model of connecting is used for analysis in ANSYS 12.0. The loading conditions are assumed to be static. Analysis done with pressure load applied at the piston end and restrained at the crank end or other load applied at the crank end and restrained at the piston end. The element chosen is SOLID 187; it was used with the tetrahedral option, making it a 10-node element with 3 degrees of freedom at each node. The finite element analysis is carried out on carbon steel connecting rod as well as on three different materials of carbon steel, aluminium boron carbide and aluminium 360. From the analysis the equivalent stress (Von-mises stress), strain, displacements were determined and are shown in figure 3-14. Table 2 shows the comparative of factor of safety for three different materials.

Fig. 5: Von Misses Stress for Carbon Steel

Fig. 6: Displacement of Carbon Steel Aluminium 360

Fig. 7: Von Misses Strain of Aluminium 360

Fig. 3: Loads and Boundary Conditions Carbon Steel:

Fig. 8: Von Misses Stress of Aluminium 360

Fig. 4: Von Misses Strain of Carbon Steel

Ajit Kumar Senapati and Gopal Krushna Mohanta

VSRDIJEECE, Vol. III (XII) December 2013 / 410

Results :

Fig. 9: Displacement of Aluminium 360 Aluminium Boran Carbide:

Fig. 10: Von Misses Strain of Aluminium Boron Carbide

Table 2 : Comparison of Factor of Safety Aluminium Material Carbon Aluminium Boron Properties Steel 360 Carbide Yield 415 172 300 strength Tensile Strength 540 317 485 (Mpa) Theoretical Factor of 6 6 6 Safety (Mpa) Allow Stress 69.17 28.47 50 ( Mpa ) Ansys Result 49 43.295 43.295 (Mpa) Working Factor of 8.47 4 6.95 Safety (N) Result For Weight of Connecting Rod : Density of Carbon steel = 7.87e-6 Kg/mm3 Volume of connecting rod = 92419.78mm3 Weight of connecting rod = Density × Volume =7.87e-6×92419.78 = 0.727 kg = 7.131 N 1. Density of Al 360 =2.685e-6 kg/mm3 Volume of connecting rod =180935.21 mm3 Weight of connecting rod =Density × Volume = 0.48581 kg = 4.765 N Percentage of reduction in weight = W of Carbon steel-W of Al 360 / W of Carbon steel =0.727-0.48581/0.727 =0.3317 Aluminium boron carbide = W of Carbon steel-W of Aluminium boron carbide/W of Carbon steel =0.727-0.48581/0.727 =0.3317

Fig. 11: Von Misses Stress Aluminium Boron Carbide

Fig. 12: Displacement Aluminium Boron Carbide

Result for Stiffness of Connecting Rod: Carbon steel Weight of connecting rod =0.727Kg Deformation =0.00941mm Stiffness =Weight/Deformation =0.727/0.0094 =77.34 kg/mm Aluminium360 Weight of connecting rod =0.48581Kg Deformation =0.0033166mm Stiffness =Weight/Deformation =0.48581/0.00331 =146.77 kg/mm Aluminium Boron Carbide Weight of connecting rod =0.48581Kg Deformation =0.012219mm

Ajit Kumar Senapati and Gopal Krushna Mohanta

Stiffness

VSRDIJEECE, Vol. III (XII) December 2013 / 411

= Weight/Deformation = 0.48581/0.012219 = 39.7585 kg/m

Result for Percentage of Increase in Stiffness: Aluminium 360 =77.34-146.77/77.34 = -0.8977 Aluminium boron carbide = 77.34-39.7585/77.34 = 0.4855 Result for Percentage of Stress Reduction : Aluminium 360 =49.625-43.925/49.625 = 0.1035 Aluminium boron carbide =49-43.925/49 = 0.1035 4. GRAPHS

Fig. 18: Working Factor of Safety for Three Materials Discussion: By checking and comparing the results of materials in above tables and finalizing the results are shown in below. For considering the parameters, the working factor of safety is nearer to theoretical factor of safety in aluminium boron carbide. Percentage of reduction in weight is same in Aluminium 360 and aluminium boron carbide. Percentage of increase in stiffness in aluminium boron carbide is more. Percentage of reducing in stress ALUMINIUM BORON CARBIDE and ALUMNUM is same than CARBON STEEL. Optimization: Objective of the optimization task was to minimize the mass of the connecting rod under the effect of a load range comprising the two extreme loads, the peak compressive gas load, such that the maximum, minimum, and the equivalent stress amplitude are within the limits of the allowable stresses.

Fig. 15: Von-Misses Stress for Three Materials a)

Fig. 16: Von-Misses Strain for Three Materials

Optimization Statement: Objective Function: Minimize Mass Subject to Constraints [1] Maximum Vonmises Stress < Allowable Stress [2] Factor of safety > 1.3 [3] Manufacturing Constraints

b) Optimized Model : After carrying out static structural analysis the stresses in each loading conditions were studied and then area where excess material can be removed were decided so that maximum Vonmises stress does not exceed allowable and factor of safety is kept above 1.3. As shown in Fig.3 Following four regions showed scope for material removal. 1. Head Region of Pin End was reduced by 1.5 mm then fillet of1.5mm was given to its sharp edges. 2. Shank of connecting rod was reduced from 3mm to 1.5mm. 3. Oil hole was given fillet of 1.2mm. 4. Head Region of Crank End was reduced by 2.2 mm and fillet of 2mm was given to its sharp edges. Optimized geometry was modified in Design modeler of ANSYS Workbench.

Fig. 17: Displacement for Three Materials

Ajit Kumar Senapati and Gopal Krushna Mohanta

VSRDIJEECE, Vol. III (XII) December 2013 / 412

Tensile Loading Compres sive Loading

Crank end Pin end Crank end Pin end

363.5 284.8 8 334.1 7 94.78

370

2.851

3.62

282.59

1.731

1.96

300.42

1.9

7.79

114.54

0.854

0.975

Fig. 13: Optimized Model of Connecting Rod Results : Maximum Vonmises stresses and deformation was found out using static structural analysis in ANSYS workbench. Fig: 4 shows stress distribution for compressive loading at crank end. In this case max stress occurred at oil hole due stress concentration. Max stress occurred in the transition area between crank end and shank region as shown in Fig: 5 for compressive loading at pin end. Stress distribution for Tensile loading at pin end is shown in Fig: 6. below shown is mass and factor of safety for both original as well as optimized model.

Fig. 14: Stress Distribution for Compressive Loading at Pin End % Weight Reduction = (Original mass-Optimized mass)/(Original mass) X 100 = (670.24-620.98)/670.24 X 100 = 7.35 %

Fig. 14 : Stress Distribution for Compressive Loading at Crank End Original Model: Mass =670.24 gm Factor of Safety = 1.31 Optimized Model: Mass = 620.98 gm Factor of safety is 1.30 Following Table 3 gives the comparison between equivalent stress and deformation at different loading conditions for original model as well as optimized model. Table 3 : Maximum Vonmises Stresses and Deformation of Original and Optimized Connecting Rod Origi Optimi Origi Optimi Model nal zed nal zed Appli Types ed Max Von misses Deformation X of press Stress (Mpa) 10-4 (m) loading ure

Discussion :  The peak stresses mostly occurred in the transition area between pin end, crank end and shank region. The value of stress at the middle of shank region is well below allowable limit.  Also forces at pin end are lower in comparison to the forces in crank end so strength of pin end should ideally be lower in comparison to the strength of crank region.  In tensile loading with pressure applied at the crank end and pin end restrained maximum value of vonmisses stress was observed for both original as well as optimized model compared to other loading conditions this is critical loading condition usedfor optimization study.  Stress concentration was occurring at the oil hole in tensile and compressive loading conditions pressure applied at crank which concluded that fillet is given to the oil hole for reduction of stress concentration. Fillet of 1.2 mm was given to oil hole.  Factor of safety was greater than 1.3 in both tensile as well as compressive loading cases for both original as well as optimized model.  Percentage weight reduction was about 7.35% which will save material directly to reduce the manufacturing cost with increased engine efficiency. Fig. 6. Stress Distribution for Tensile loading at Pin end. 5. CONCLUSION Finite Element analysis of the connecting rod of a Hero Honda Splendor has been done using FEA tool

Ajit Kumar Senapati and Gopal Krushna Mohanta

ANSYSWorkbench. From the results obtained from FE analysis, many discussions have been made. The results obtained are well in agreement with the similar available existing results. The model presented here, is well safe and under permissible limit of stresses.  Conclusion is based on the current work that the design parameter of connecting rod with modification gives sufficient improvement in the existing results.  The weight of the connecting rod is also reduced by 0.477g. Thereby, reduces the inertia force.  Fatigue strength is the most important driving factor for the design of connecting rod and it is found that the fatigue results are in good agreement with the existing result.  The stress is found maximum at the piston end so the material is increased in the stressed portion to reduce stress. 6. REFERENCES [1] Webster, W., Coffell, R., and Alfaro, D., "A Three Dimensional Finite Element Analysis of a High Speed Diesel Engine Connecting Rod," SAE Technical Paper 831322, 1983, doi: 10.4271/831322 [2] Xianjun Hou ; Cuicui Tian ; Dan Fang ; Fuming Peng ; Fuwu Yan. Computational Intelligence and Software Engineering, 2009. CiSE 2009. International Conference on “Sensitivity Analysis and Optimization for Connecting Rod of LJ276M Electronic Gasoline Engine “Digital Object Identifier 10.1109/CISE.2009.5363219,Publication Year: 2009, Page(s): 1 - 5 [3] Tae Hee Lee, J.J. Jung, ”Metamodel-Based Shape Optimization of Connecting Rod Considering Fatigue Life”2006, Key Engineering Materials, 306-308, 211. [4] S.Charkha, Jaju, “Analysis & Optimization ofConnecting Rod “S.B. P.G. Dept. of Mech. Eng., Pankaj Laddhad Inst. of Technol. & Manage. Studies, Buldana, India Emerging Trends in Engineering and Technology (ICETET), 2009 2nd International Conference [5] Zheng Bin ,Liu Yongqi ; Ji Lixia Structural Improvement of Diesel Engine Connecting Rod. Computer Modeling and Simulation, 2010. ICCMS '10. Second International Conference on (Volume: 1) Page(s):175 - 178 [6] Bin Zheng, ,Yongqi Liu,, Ruixiang Liu, Jian Meng “The exterior surface of the transition location of small end and connecting rod shank is the exposed destructive position at maximum compression condition” Advances in Computer Science, Intelligent System and Environment ,Advances in Intelligent and Soft Computing Volume 105, 2011, pp 473477 [7] M.S. Shaari, M.M. Rahman1, M.M. Noor, K. Kadirgama1and A.K. Amirruddin” Design Of Connecting Rod Of Internal Combustion Engine:A Topology Optimization Approach”National Conference in Mechanical Engineering Research and Postgraduate Studies (2nd NCMER 2010) 3-4 December 2010, Faculty of Mechanical Engineering, UMP Pekan, Kuantan, Pahang, Malaysia; pp. 155-166 [8] M. Omid, S.S. Mohtasebi, S.A. Mireei and E. Mahmoodi, “Fatigue Analysis of Connecting Rod of U650 Tractor in the Finite Element Code ANSYS. Journal of Applied Sciences, 2008. 4338-4345. Books: [9] R.S. KHURMI, J.K GUPTA. (Machine design) Edition 14, Publisher Chand (S.) & Co Ltd, India; Reprint Edition

VSRDIJEECE, Vol. III (XII) December 2013 / 413

2006 edition (3 July 2005) ISBN-10: 8121925371 [10] K. Lingaiah-Design Data Hand Book, McGraw Hill, 2nd Ed. 2003. [11] K. Mahadevan and Balaveera Reddy, Design Data Hand Book, CBS Publication [12] S.Md. JALALUDEEN, (Machine design) Anuradha Agencies Publications, 2009 http://www.technicaljournalsonline.com/ijaers/voli/ijaers vol i issue ii [13] Joseph E Shigley and Charles R. Mischke Mechanical Engineering Design, McGraw Hill International edition,6th Edition, 2003.

 

Ajit Kumar Senapati and Gopal Krushna Mohanta

VSRDIJEECE, Vol. III (XII) December 2013 / 414

