Design and Analysis of connecting rod ABSTRACTThe main objective of this project is to explore weight reduction opportunities for a production of forged steel connecting rod. This has entailed performing a detailed load analysis. Therefore, this study has dealt with two subjects, first, static load stress analysis of the connecting rod, and second, optimization for weight.

In this project, finite element analysis of single cylinder four stroke petrol engines is taken as a case study. Structural systems of connecting rod can be easily analyzed using Finite Element techniques. So firstly a proper Finite Element Model is developed using Cad software Pro/E Wildfire 5.0. Then the Finite element analysis is done to determine the total deformation in the existing connecting rod for the given loading conditions using Finite Element Analysis software ANSYS WORKBENCH. In the first part of the study, the static loads acting on the connecting rod, after that the work is carried out for material optimization (SG iron and forged steel ). Based on the observations of the static Finite Element Analysis (FEA) and the load analysis results, the load for the optimization study was selected. The results were also used to determine the total deformation for the two materials.

CHAPTER-I

INTRODUCTION

BACKGROUND OF THE CONNECTING ROD

The automobile engine connecting rod is a high volume production, critical component. It connects reciprocating piston to rotating crankshaft, transmitting the thrust of the piston to the crankshaft. Every vehicle that uses an internal combustion engine requires at least one connecting rod depending upon the number of cylinders in the engine.

Connecting rods for automotive applications are typically manufactured by forging from either wrought steel or powdered metal. They could also be cast. However, castings could have blow-holes which are detrimental from durability and fatigue points of view. The fact that forgings produce blow-hole-free and better rods gives them an advantage over cast rods (Gupta, 1993). Between the forging processes, powder forged or drop forged, each process has its own pros and cons. Powder metal manufactured blanks have the advantage of being near net shape, reducing material waste. However, the cost of the blank is high due to the high material cost and sophisticated manufacturing techniques (Repgen, 1998). With steel forging, the material is inexpensive and the rough part manufacturing process is cost effective. Bringing the part to final dimensions under tight tolerance results in high expenditure for machining, as the blank usually contains more excess material (Repgen, 1998). A sizeable portion of the US market for connecting rods is currently consumed by the powder metal forging industry. A comparison of the

European and North American connecting rod markets indicates that according to an unpublished market analysis for the year 2000 (Ludenbach, 2002), 78% of the connecting rods in Europe (total annual production: 80 million approximately) are steel forged as opposed to 43% in North America (total annual production: 100 million approximately),

In order to recapture the US market, the steel industry has focused on development of production technology and new steels. AISI (American Iron and Steel Institute) funded a research program that had two aspects to address. The first aspect was to investigate and compare fatigue strength of steel forged connecting rods with that of the powder forged connecting rods. The second aspect was to optimize the weight and manufacturing cost of the steel forged connecting rod. The first aspect of this research program has been dealt with in a masters thesis entitled Fatigue Behavior and Life predictions of Forged Steel and PM Connecting Rods (Afzal A., 2004). This current thesis deals with the second aspect of the study, the optimization part.

Due to its large volume production, it is only logical that optimization of the connecting rod for its weight or volume will result in large-scale savings. It can also achieve the objective of reducing the weight of the engine component, thus reducing inertia loads, reducing engine weight and improving engine performance and fuel economy.

In order to understand the true impact the automobile has had on our society, we would have to go back in time over one hundred years. A time without the simplicity of hopping into a vehicle to take us anywhere we want to go is almost unfathomable to many Americans. But for the early automotive engineers, the tremendous advancements in automotive technology would be even more surprising.

In the last 50 years, cars have learned to think, adjust, and even protect. But this is just the tip of the iceberg. High performance is now the catch phrase. The vast majority of people want a vehicle that will get them from point A to point B as easily as possible, but also put a little smile on their faces. Often times, the smile is created by a quick punch of the accelerator and accompanied by a feeling of immense power and control. The auto manufacturers are well aware of this, and to achieve it, they design faster, lighter, and more efficient engines to do the job. But exactly what happens inside an engine and what are the risks involved in designing the strongest engine on the block.

In this project, one component of an engine in particular, the connecting rod, will be analyzed. Being one of the most integral parts in an engines design, the connecting rod must be able to withstand tremendous loads and transmit a great deal of power. It is no surprise that a failure in a connecting rod can be one of the most costly and damaging failures in an engine. But simply saying that isnt enough to fully understand the dynamics of the situation.

Throughout the course of this project, an idealized model of a connecting rod, piston, and flywheel will be modeled and analyzed. It will become apparent exactly why these parts are so important to the operation of an automobile, and furthermore how prone to failure they can be. However, before too much more is said on the engineering details, a little background information is necessary.

FUNDAMENTALS

Below is a picture of the fundamental parts of an engine. Surface "L" is where combustion occurs, air enters through "M", and "H" is the shaft through which power is accumulated and delivered out of the engine. The combustion occurs against the top surface of the piston (F) and pushes the connecting rod (G) downward, causing the shaft to move in a circular motion. So, it is easy to see that the connecting rod harnesses all of the power produced in combustion and converts it into something useful, in this case a spinning shaft.

PRESSURE IN A FOUR-STROKE ENGINE

Up to this point, the variable P has gone unmentioned. The pressure in the cylinder (P) is not an easy thing to model for a situation like this, yet it is one of the most important factors in the final analysis. To be able to explain how P fluctuates, it is once again necessary to give a little background on a four-stroke engine.

A four-stroke engine is the most common type used in automobiles. The four strokes are intake, compression, power, and exhaust. Each stroke requires approximately 180 degrees of crankshaft (or flywheel) rotation, so the complete cycle would take 720 degrees. Each stroke plays a very important role in the combustion process, and each has a different pressure surrounding it.

In the intake cycle, as the picture shows, the piston is moving downward while one of the valves is open. This creates a vacuum, and an air-fuel mixture is sucked into the chamber. This would be cause for very little pressure on the piston, so P is small.

Moving on to compression, we can see that both valves are closed, and the piston is moving upward. This creates a much larger amount of pressure on the piston, so we would have a different representation of P in our equation for this stroke.

The next stroke is the big one: power. This is where the compressed air-fuel mixture is ignited with a spark, causing a tremendous jump in pressure as the fuel burns. The pressure seems to "spike", so the most cause for concern occurs here. (This is also the area in which the dangers of engine knock or pre-detonation can occur, causing an even larger spike.)

Finally, we have the exhaust stroke. In this stroke, the exhaust valve is open, once again creating a chamber of low pressure. So, as the piston moves back upwards, it forces all the air out of the chamber. The pressure in this region is therefore considered very low.

So, given the understanding of how a four-stroke engine works, we must now model the variable pressure for all 720 degrees (or 12.57 radians). Creating a piecewise-defined function does this. However, we still need to find some basic values for the pressure, and for the purposes of this project, a particular graphical representation was chosen:

COMPOUND RODS

Many-cylinder multi-bank engines such as a V-12 layout have little space available for many connecting rod journals on a limited length of crankshaft. This is a difficult compromise to solve and its consequence has often led to engines being regarded as failures (Sunbeam Arab, Rolls-Royce Vulture).

The simplest solution, almost universal in road car engines, is to use simple rods where cylinders from both banks share a journal. This requires the rod bearings to be narrower, increasing bearing load and the risk of failure in a high-performance engine. This also means the opposing cylinders are not exactly in line with each other.

In certain engine types, master/slave rods are used rather than the simple type shown in the picture above. The master rod carries one or more ring pins to which are bolted the much smaller big ends of slave rods on other cylinders. Radial engines typically have a master rod for one cylinder and slave rods for all the other cylinders in the same bank. Certain designs of V engines use a master/slave rod for each pair of opposite cylinders. A drawback of this is that the stroke of the subsidiary rod is slightly shorter than the master, which increases vibration in a vee engine, catastrophically so for the Sunbeam Arab.

The usual solution for high-performance aero-engines is a "forked" connecting rod. One rod is split in two at the big end and the other is thinned to fit into this fork. The journal is still shared between cylinders. The Rolls-Royce Merlin used this "fork-and-blade"style.

VEHICLE TYPE MARUTI-800

Maruti-800 engine

Manufacturer : maruti udyog ltd., India

Engine type: 3 cylinder, in-line overhead camshaft, water cooled type.

Bore: 68.5 mm

Stroke: 72.0mm

Piston displacement: 796cc

Compression ratio: 8.71

Firing order: 1-3-2

Maximum power: 29.5 kW (40 bhp) at 5500rpm

: 33.6kw (45bhp) at 6000rpm (EURO II MODEL)

Maximum torque: 55.9Nm (5.7kgm) at 2500rpm

: 60.8Nm (6.2kgm) at 3000rpm (EURO II MODEL)

Lubrication: wet sump

Fuel system: solx mikuni 24-30 DIDS (MPFI in euro II model)

Fuel tank capacity: 30liters

Ignition: battery ignition system

Electronic ignition in euro II model

HISTORY

Scheme of the Roman Hierapolis sawmill, the earliest known machine to combine a connecting rod with a crank.

The earliest evidence for a connecting rod appears in the late 3rd century AD Roman Hierapolis sawmills. It also appears in two 6th century Eastern Roman saw mills excavated at Ephesus respectively Grease. The crank and connecting rod mechanism of these Roman watermills converted the rotary motion of the waterwheel into the linear movement of the saw blades.

In China, a crank and connecting rod machine appeared in the 5th century, followed by a crank and connecting rod machine with a piston rod in the 6th century. Sometime between 1174 and 1206, the Arab inventor and engineer Al-Jazari described a machine which incorporated the connecting rod with a crankshaft to pump water as part of a water-raising machine.

CHAPTER-II

INTRODUCTION TO PRO-E

Pro/ENGINEER, PTC's parametric, integrated 3D CAD/CAM/CAE solution, is used by discrete manufacturers for mechanical engineering, design and manufacturing. Created by Dr. Samuel P. Geisberg in the mid-1980s, Pro/ENGINEER was the industry's first successful parametric, 3D CAD modeling system. The parametric modeling approach uses parameters, dimensions, features, and relationships to capture intended product behavior and create a recipe which enables design automation and the optimization of design and product development processes. This powerful and rich design approach is used by companies whose product strategy is family-based or platform-driven, where a prescriptive design strategy is critical to the success of the design process by embedding engineering constraints and relationships to quickly optimize the design, or where the resulting geometry may be complex or based upon equations. Pro/ENGINEER provides a complete set of design, analysis and manufacturing capabilities on one, integral, scalable platform. These capabilities, include Solid Modeling, Surfacing, Rendering, Data Interoperability, Routed Systems Design, Simulation, Tolerance Analysis, and NC and Tooling Design.

Companies use Pro/ENGINEER to create a complete 3D digital model of their products. The models consist of 2D and 3D solid model data which can also be used downstream in finite element analysis, rapid prototyping, tooling design, and CNC manufacturing. All data is associative and interchangeable between the CAD, CAE and CAM modules without conversion. A product and its entire bill of materials (BOM) can be modeled accurately with fully associative engineering drawings, and revision control information. The associativity in Pro/ENGINEER enables users to make changes in the design at any time during the product development process and automatically update downstream deliverables. This capability enables concurrent engineering design, analysis and manufacturing engineers working in parallel and streamlines product development processes.

CONNECTING ROD DESIGN

EXTRUDE CUT MODEL FOR CONNECTING ROD

DIMENSIONS OF THE CONNECTING ROD-DESIGN

CHAPTER-III

INTRODUCTION TO ANSYS

ANSYS is an engineering simulation software provider founded by software engineer John Swanson. It develops general-purpose finite element analysis and computational fluid dynamics software. While ANSYS has developed a range of computer-aided engineering (CAE) products, it is perhaps best known for its ANSYS Mechanical and ANSYS Multiphysics products.

ANSYS Mechanical and ANSYS Multiphysics software are non exportable analysis tools incorporating pre-processing (geometry creation, meshing), solver and post-processing modules in a graphical user interface. These are general-purpose finite element modeling packages for numerically solving mechanical problems, including static/dynamic structural analysis (both linear and non-linear), heat transfer and fluid problems, as well as acoustic and electro-magnetic problems.

ANSYS Mechanical technology incorporates both structural and material non-linearitys. ANSYS Multiphysics software includes solvers for thermal, structural, CFD, electromagnetics, and acoustics and can sometimes couple these separate physics together in order to address multidisciplinary applications. ANSYS software can also be used in civil engineering, electrical engineering, physics and chemistry.

ANSYS, Inc. acquired the CFX computational fluid dynamics code in 2003 and Fluent, Inc. in 2006. The CFD packages from ANSYS are used for engineering simulations. In 2008, ANSYS acquired Ansoft Corporation, a leading developer of high-performance electronic design automation (EDA) software, and added a suite of products designed to simulate high-performance electronics designs found in mobile communication and Internet devices, broadband networking components and systems, integrated circuits, printed circuit boards, and electromechanical systems. The acquisition allowed ANSYS to address the continuing convergence of the mechanical and electrical worlds across a whole range of industry sectors.

GEOMETRY VIEW OF CONNECTING ROD IN ANSYS WORKBENCH

CHAPTER-IV

MODELLING COMMANDS USED IN PRO-E

CREATE THE WORKING DIRECTORY-First create the working directory to save the all model in one folder

File set working directory selects the required folder ok.

SKETCH- This command is used to create the new sketch like circle, line, rectangle, ellipse, etc,..

The pro-e window select the sketch icon and select the plane or surface want to sketch.

CIRCLE- This command is used to create the circle. Create circle by picking the center point and a point on the circle from Right Tool chest.

Pick the origin for the circles center - pick a point on the circles edge- click the middle mouse button ok

ELLIPSE- This command is used to create the ellipse. Create ellipse by picking the center point and a minor radius point and major radius point, the minor and major radius of the ellipse is vertical and horizontal direction depend upon the shape of ellipse we want.

Select the ellipse icon from right tool chest- Pick the center for the ellipse pick the minor radius of ellipse point and pick the major radius of the ellipse- click the middle mouse button ok

LINE- This command is used to create the line. Create the line by start point and end point.

Select the line icon from the right Tool chest click the start point of the line click the end point of the circle -enter

ARC- This command is used to create the arc. Create the arc by using three points. The three points are start point, end point and center point of the arc.

Select the arc icon from the right Tool chest click the start point of the arc click the end point of the arc and click the middle point of the arc enter.

The dimension of the arc is modified by double click on the arc then the dimension will appear in the pop up box, then provide the value of the arc.

CREATE THE HEXAGON The hexagon is created by insert foreign data icon in the Right Tool chest.

Insert foreign data from Palette into active object - scroll down to see the hexagon - double-click hexagon- Place the hexagon on the sketch by picking a position - with the left mouse button, drag and drop the center of the hexagon at the origin - modify Scale value to the required size click enter

RECTANGLE- This command is used to create the rectangle and square.

Click the rectangle icon in the right Tool chest click the lower left point of the rectangle and higher right corner of the rectangle we want to draw.

After drawing the rectangle the dimension of the rectangle is provided by the pick the dimension command from the dimension icon in the right toolchest of the pro-e software.

DIMENSION- This command is used to provide the dimension of the sketched entities the entities may be circle, line, rectangle, ellipse, etc,..

The dimension is provide to the sketch by select the dimension icon from the right tool chest then select the sketched entities and press the middle mouse button to finish the dimensioning.

To change the dimension of the sketched entities by just double click the dimension line of created sketch.

EXTRUDE This command is used to create the material (to make 3D object from 2D sketch) from the sketched entities. The entities may be circle, line or rectangle, etc,...

Select the extrude icon from the right tool chest then select the sketched part in the window, enter the extrude length and press the middle mouse button to finish the extrude command.

REVOLVE- This command is used to create the material from taking the one axis and sketched entities. The axis is the center of the revolved part. The revolve angle should between 0 degree to 360 degree.

Select the revolve icon from the right tool chest then select the sketched part and axis of the object in the graphical window, enter the revolve angle and press the middle mouse button to finish the extrude command.

SWEEP FEATURES

The Sweep option extrudes a section along a defined trajectory. The order of operation is to first create a trajectory and then a section. A trajectory is a path along which a section is swept. The trajectory for a sweep feature can be sketched or selected. The Sweep option of protrusion is similar to the Extrude option. The only difference is that in the case of the Extrude option, the feature is extruded in a direction normal to the sketching plane, but in the case of the Sweep option, the section is swept along the sketched or selected trajectory. The trajectory can be open or closed. Normal sketching tools are used for sketching the trajectory. The cross-section of the swept feature remains constant throughout the sweep.

SWEEP CUT

To create a Sweep Cut feature, the procedure to be followed is the same as that in Sweep Protrusion. The only difference is that in case of cut features, the material is removed from an existing feature.

The Cut option can be invoked by choosing Insert > Sweep > Cut from the menu bar. A cut can be a solid swept cut or a thin swept cut.

CHAPTER-V

INTRODUCTION & HISTORY OF FEA

INTRODUCTION TO FEA

FEA consists of a computer model of a material or design that is stressed and analyzed for specific results. It is used in new product design, and existing product refinement. A company is able to verify a proposed design will be able to perform to the client's specifications prior to manufacturing or construction. In case of structural failure, FEA may be used to help determine the design modifications to meet the new condition.

There are generally two types of analysis that are used in industry: 2-D modeling, and 3-D modeling. While 2-D modeling conserves simplicity and allows the analysis to be run on a relatively normal computer, it tends to yield less accurate results. 3-D modeling, however, produces more accurate results while sacrificing the ability to run on all but the fastest computers effectively. Within each of these modeling schemes, the programmer can insert numerous algorithms (functions) which may make the system behave linearly or non-linearly. Linear systems are far less complex and generally do not take into account plastic deformation. Non-linear systems do account for plastic deformation, and many also are capable of testing a material all the way to fracture.

HISTORY OF FEA

Finite Element Analysis (FEA) was first developed in 1943 by R. Courant, who utilized the Ritz method of numerical analysis and minimization of variation calculus to obtain approximate solutions to vibration systems. Shortly thereafter, a paper published in 1956 by M. J. Turner, R. W. Clough, H. C. Martin, and L. J. Topp established a broader definition of numerical analysis. The paper centered on the "stiffness and deflection of complex structures". By the early 70's, FEA was limited to expensive mainframe computers generally owned by the aeronautics, automotive, defense, and nuclear industries. Since the rapid decline in the cost of computers and the phenomenal increase in computing power, FEA has been developed to an incredible precision. Present day supercomputers are now able to produce accurate results for all kinds of parameters.

CHAPTER-VI

NODES AND ELEMENTS

Red dots represent the element's nodes.

Elements can have straight or curved edges.

Each node has three unknowns, namely, the translations in the three global directions.

The process of subdividing the part into small pieces (elements) is called meshing. In general, smaller elements give more accurate results but require more computer resources and time.

Ansys suggests a global element size and tolerance for meshing. The size is only an average value, actual element sizes may vary from one location to another depending on geometry.

It is recommended to use the default settings of meshing for the initial run. For a more accurate solution, use a smaller element size.

MESH VIEW OF CONNECTING ROD IN ANSYS WORKBENCH

CHAPTER-VII

ANALYSIS PROCEDURE

STATIC STRUCTURAL

A static structural analysis determines the displacements, stresses, strains, and forces in structures or components caused by loads that do not induce significant inertia and damping effects. Steady loading and response conditions are assumed; that is, the loads and the structure's response are assumed to vary slowly with respect to time. The types of loading that can be applied in a static analysis include:

Externally applied forces and pressures

Steady-state inertial forces (such as gravity or rotational velocity)

Imposed (nonzero) displacements

Temperatures (for thermal strain)

ANALYZING THE CONNECTING ROD STEP BY STEP PROCEDURE

The 3D model of the connecting rod 3D model is converted as iges format through the PRO-E software

The IGES (Initial Graphic Exchange Specification) format is suitable to import in the ANSYS Workbench for analyzing

open the ANSYS workbench

Create new geometry

File import external geometry file generate

Project new mesh

Defaults physical preference mechanical

Advanced relevance center fine

Advanced element size default

Right click the mesh in tree view generate mesh

Project convert to simulation yes

Select the all solid in geometry tree

Definition material import

import select material spheroidal graphite cast iron

New analysis static structural(compressive force)

Static structural right click insert fixed support

Inner surface of piston pin end and locking side of crank shaft of connecting rod with DOF =0

Geometry apply

Static structural insert force select the inner face of the piston pin which is compressive force direction of inner side

Geometry apply

Magnitude 26.7

Geometry apply

Static structural insert force select the inner face of the bearing couple side which is compressive force direction of inner side

Geometry apply

Magnitude 26.7

Geometry apply

Rotational velocity = 6000rpm

Geometry apply

Moment =60.3 N.mm

Solution insert the total deformation, equivalent elastic strain, and equivalent stress.

Right click the solution icon in the tree solve

After solve the analysis take the reading of above mentioned items (i.e. total deformation, equivalent elastic strain, etc,)

The all results are taken in a picture and save it to the required folder in the system

The material is changed to CARBON EPOXY in the previous steps the loads are to be same as the spheroidal graphite cast iron

Solve again this analysis in the CARBON EPOXY material

Now take again the readings save the picture to the required folder in the system

The all readings are tabulated

The results are compared

Finally we get the good material to resist the load is obtained through this analysis

LOADS & SUPPPORT APPLIED ON THE PRESENT MATERIAL ( FORGED STEEL) OF CONNECTING ROD (COMPRESSIVE LOAD) IN ANSYS WORKBENCH

CHAPTER-VIII

MATERIAL PROPERTIES

Carbon fiber (carbon fibre), alternatively carbon epoxy, is a material consisting of extremely thin fibers about 0.0050.010mm in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in microscopic crystals that are more or less aligned parallel to the long axis of the fiber. The crystal alignment makes the fiber very strong for its size. Several thousand carbon fibers are twisted together to form a yarn, which may be used by itself or woven into a fabric. Carbon fiber has many different weave patterns and can be combined with a plastic resin and wound or molded to form composite materials such as carbon fiber reinforced plastic (also referenced as carbon fiber) to provide a high strength-to-weight ratio material. The density of carbon fiber is also considerably lower than the density of steel, making it ideal for applications requiring low weight. The properties of carbon fiber such as high tensile strength, low weight, and low thermal expansion make it very popular in aerospace, civil engineering, military, and motorsports, along with other competition sports. However, it is relatively expensive when compared to similar materials such as fiberglass or plastic. Carbon fiber is very strong when stretched or bent, but weak when compressed or exposed to high shock (eg. a carbon fiber bar is extremely difficult to bend, but will crack easily if hit with a hammer).PROPERTYCONDITIONS

UNITSVALUE

Compressive StrengthMPa

800-1300

Densityg.cm-31.6

Flexural strength MPa1200

Tensile strengthMPa50

Thermal Expansionx10-6 K-128

Ultimate Compressive Strain%2.5

Ultimate Tensile Strain%0.5

Young's ModulusGPa120-140

Poisson's Ratio0.32

Specific Heat Capacity J/kg-C1530

Thermal Conductivity (W/m-K)15-22

CHAPTER-IX

ANALYSIS SETTINGS

FIXED SUPPORT

ROTATIONAL VELOCITY

FORCE APPLIED ON THE GEOMENTRY

MOMENT

RESULTS FOR CONVENTIONAL MATERIAL FORGED STEEL

REULTS FOR SG COMPRESSIVE LOAD

RESULTS FOR CARBON EPOXYTOTAL DEFORMATION

EQUIVALENT STRAIN

EQUIVALENT STRESS

CHAPTER-X

TABULATIONCOMPARISION OF DEFORMATION

S.NOMATERIALTOTAL DEFORMATIONEQUIVALENT ELASTIC STRAINEQUIVALENT STRESS

1FORGED STEEL0.010030.00102226.85

2SG0.0185030.0018614223.37

3CARBON EPOXY0.0170420.0016995203.94

CHAPTER-XI

CONCLUSION

The project carried out by us will make an impressing mark in the field of automobile. This project we are study about the connecting rod.

Doing this project we are study about the 3Dmodelling software (PRO-E) and Study about the analyzing software (ansys) to develop our basic knowledge to know about the industrial design.

REFERENCE

1. Design data book

-P.S.G.Tech.

2. Machine tool design handbook Central machine tool Institute,

Bangalore.

3. Strength of Materials- R.S.Kurmi

4. Manufacturing Technology - M.Haslehurst.

5. Design of machine elements - R.S.Kurmi

6. www.matweb.com

7. www.efunda.com