R. CH. S. NAGA PRASAD

Transcription

1 ISSN Vol.06,Issue.17 May-2017, Pages: Design and Analysis of 150CC IC Engine Connecting Rod DR. CH. S. NAGA PRASAD Professor & Principal, Dept of Mechanical Engineering, GIITS Engineering College, Aganampudi, Visakhapatnam (Dt), AP, India, Abstract: The connecting rod is the intermediate member between the piston and the crankshaft. Its primary function is to transmit the push and pull from the piston pin to the crank pin and thus convert the reciprocating motion of the piston into rotary motion of the crank. In our project we design a connecting rod for a four stroke single cylinder engine for two different materials forged steel and Aluminum alloy Connecting rod modeled in 3D modeling software CREO parametric. In this thesis the static analysis is to determine the deformation, stress and strain on the connecting rod by applying the pressure developed in the engine. Modal analysis is to determine the natural frequencies and deformation at different mode shapes. Fatigue analysis is to determine to estimate life of the connecting rod. The analysis is done to verify the better material for connecting rod to reduce the cost. Modeling is done in CREO and analysis is done in ANSYS. Keywords: Finite Element Analysis, Connecting Rod, Static And Model Analysis. I. INTRODUCTION In a reciprocating piston engine, the connecting rod connects the piston to the crank or crankshaft. In modern automotive internal, the connecting rods are most usually made of steel for production engines, but can be made of aluminum (for lightness and the ability to absorb high impact at the expense of durability) or titanium (for a combination of strength and lightness at the expense of affordability) for high performance engines, or of cast iron for applications such as motor scooters. They are not rigidly fixed at either end, so that the angle between the connecting rod and the piston can change as the rod moves up and down and rotates around the crankshaft. Condors, especially in racing engines, may be called "billet" rods, if they are machined out of a solid billet of metal, rather than being cast. Fig.1. The small end attaches to the piston pin, gudgeon pin (the usual British term) or wrist pin, which is currently most often press fit into the con rod but can swivel in the piston, a "floating wrist pin" design. The big end connects to the bearing journal on the crank throw, running on replaceable bearing shells accessible via the con rod bolts which hold the bearing "cap" onto the big end; typically there is a pinhole bored through the bearing and the big end of the con rod so that pressurized lubricating motor squirts out onto the thrust side of the cylinder wall to lubricate the travel of the pistons and piston rings. The con 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. Failure of a connecting rod, usually called "throwing a rod" is one of the most common causes of catastrophic engine failure in cars, frequently putting the broken rod through the side of the crankcase and thereby rendering the engine irreparable; it can result from fatigue near a physical defect in the rod, lubrication failure in a bearing due to faulty maintenance, or from failure of the rod bolts from a defect, improper tightening, or re-use of already used (stressed) bolts where not recommended. Despite their frequent occurrence on televised competitive automobile events, such failures are quite rare on production cars during normal daily driving. This is because production auto parts have a much larger factor of safety, and often more systematic quality control. When building a high performance engine, great attention is paid to the con rods, eliminating stress risers by such techniques as grinding the edges of the rod to a smooth radius, shot peening to induce compressive surface stresses 2017 IJSETR. All rights reserved.

2 (to prevent crack initiation), balancing all con rod/piston assemblies to the same weight and Magnafluxing to reveal otherwise invisible small cracks which would cause the rod to fail under stress. In addition, great care is taken to torque the con rod bolts to the exact value specified; often these bolts must be replaced rather than reused. The big end of the rod is fabricated as a unit and cut or cracked in two to establish precision fit around the big end bearing shell. Therefore, the big end "caps" are not interchangeable between con rods, and when rebuilding an engine, care must be taken to ensure that the caps of the different con rods are not mixed up. Both the con rod and its bearing cap are usually embossed with the corresponding position number in the engine block. DR. CH. S. NAGA PRASAD Pro/ENGINEER CAD/CAM/CAE solutions allow you to design faster than ever, while maximizing innovation and quality to ultimately create exceptional products. B. Different Modules In Pro/Engineer Part design, Assembly, Drawing& Sheet metal. C. Introduction To Finite Element Method Finite Element Method (FEM) is also called as Finite Element Analysis (FEA). Finite Element Method is a basic analysis technique for resolving and substituting complicated problems by simpler ones, obtaining approximate solutions Finite element method being a flexible tool is used in various industries to solve several practical engineering problems. In finite element method it is feasible to generate the relative results. IV. RESULTS AND DISCUSSIONS: A. Models of Cantilever Beam Using Creo Parametric The cantilever beam is modeled using the given specifications and design formula from data book. The cantilever beam outer casing body profile is sketched in sketcher and then it is extruded using extrude option as shown in Figs.3 to 21. Fig.2. II. PROBLEM DESCRIPTION The objective of this project is to make a 3D model of the connecting rod and study the static and model behavior of the cantilever beam by performing the finite element analysis. 3D modeling software (PRO-Engineer) was used for designing and analysis software (ANSYS) was used for static and modal analysis. The Methodology Followed In The Project Is As Follows: Create a 3D model of the cantilever beam assembly using parametric software creo. Convert the surface model into Para solid file and import the model into ANSYS to do analysis. Perform static analysis on the cantilever beam. Perform model analysis on the existing model of the cantilever beam. Fig.3. Material Forged Steel: III. INTRODUCTION TO CAD/CAE Computer-aided design (CAD), also known as computeraided design and drafting (CADD), is the use of computer technology for the process of design and designdocumentation. A. Introduction To Pro-Engineer Pro/ENGINEER Wildfire is the standard in 3D product design, featuring industry-leading productivity tools that promote best practices in design while ensuring compliance with your industry and company standards. Integrated Fig.4. Deformation.

3 Design and Analysis of 150CC IC Engine Connecting Rod Fig.5. Stress. Fig.8. Stress. Fig.6.Strain. Material Aluminum Alloy 7075: Fig.9. Strain. Fatigue Analysis of Connecting Rod Material Forged Steel: Fig.7. Deformation. Fig.10. Life.

4 DR. CH. S. NAGA PRASAD Fig.11. Damage. Fig.14. Damage. Fig.12. Safety factor. Material Aluminum Alloy 7075: Fig.15. Safety factor. Modal Analysis Of Connecting Rod Material Forged Steel: Fig.13. Life. Fig.16. Mode shape -1.

5 Design and Analysis of 150CC IC Engine Connecting Rod Fig.17. Mode shape -2. Fig.20. Mode shape -2. Fig.18. Mode shape -3. Material Aluminum Alloy 7075: Fig.21. Mode shape -3. V. RESULTS AND DISCUSSIONS CFD ANALYSIS RESULT TABLE A. Static Analysis Results Results Table: TABLE I: Static Analysis Results TABLE II: Modal Analysis Results Fig.19. Mode shape -1.

6 DR. CH. S. NAGA PRASAD TABLE III: Fatigue Analysis Results VI. CONCLUSION Structural analysis is done on the connecting rod to verify the strength of the connecting rod original and modified model by using two materials Aluminum alloy by applying the pressure developed in the engine. Modal analysis is done to determine the natural frequencies and deformation. The analysis is done to verify the better material for connecting rod to reduce the weight. Modeling is done in CREO and analysis is done in ANSYS. By observing the static analysis results the stress values are less for aluminum alloy 7075 than forged steel. By observing the modal analysis the deformation values are more for aluminum alloy So it can be conclude the aluminum alloy 7075 material is the better for connecting rod. Manufacturing done by the material aluminum alloy 7075 because aluminum alloy 7075 is lite weight material and observing the above results the aluminum alloy 7075 material is to reduce the weight of the connecting rod. VII. REFERENCES [1] Z.W. Yu, X.L. Xu Failure analysis of diesel engine rocker arms Engineering Failure Analysis, Volume 13, Issue 4, June 2006, Pages [2] Chin-Sung Chung, Ho-Kyung Kim Safety evaluation of the rocker arm of a diesel engine Materials & Design, Volume 31, Issue 2,February 2010, Pages ` [3] Dong-Woo Lee, Soo-Jin Lee, Seok-Swoo Cho, WonSikJoo Failure of rocker arm shaft for 4-cylinder SOHC engine. [4] Dong Woo Lee, SeokSwoo Cho and Won SikJoo An estimation of failure stress condition in rocker arm shaft through FEA and microscopic fractography [5] James M. miller Rocker arm having perpendicular geometry at valve mid lift united states patent Appl. No.211, 638.Dec1, Author Profile: DR.CH.S.Naga Prasad received his M.Tech Degree on Heat power Refrigerator and AC from JNTU, Anantapur in 2002 and Ph.D on IC Engines (Thermal Engg) from JNTU, Hyderabad in He is currently working as Professor & Principal in Gonna Institute of Information Technology and sciences, Aganampudi, Visakhapatnam, A.P, INDIA.