Group Project

AHLI : JAMIUL SATTAR BIN ABDUL RAHIMMATRIX :

AHLI : WAN MOHD AZROL KHAIRIL BIN WAN MOHD YASINMATRIX : SX070849MMJ08

AHLI : MATRIX :

AHLI : MATRIX :

AHLI :

MATRIX :

LECTURE : AHMAD ZAFRI BIN ZAINUDINCODE / COURSE

: SME 3033 / FINETE ELEMENTS METHOD

TABLE OF CONTENT

INTRODUCTION.........................................................................................................................3

GEOMETRY, LOADING AND BOUNDARY CONDITIONS..................................................6

MATERIAL...................................................................................................................................9

RESULT AND DISCUSSION..................................................................................................10

INTRODUCTION

In a reciprocating piston engine, the connecting rod or conrod connects

the piston to the crank or crankshaft. Together with the crank, they form a simple

mechanism that converts reciprocating motion into rotating motion. Connecting rods

may also convert rotating motion into reciprocating motion. Historically, before the

development of engines, they were first used in this way. As a connecting rod is

rigid, it may transmit either a push or a pull and so the rod may rotate the crank

through both halves of a revolution, i.e. piston pushing and piston pulling. Earlier

mechanisms, such as chains, could only pull. In a few two-stroke engines, the

connecting rod is only required to push.

Today, connecting rods are best known through their use in internal

combustion piston engines, such as automotive engines. These are of a distinctly

different design from earlier forms of connecting rods, used in steam engines and

steam locomotives. In modern automotive internal combustion engines, the

connecting rods are most usually made of steel for production engines, but can be

made of T6-2024 and T651-7075 aluminium alloys[citation needed] (for lightness and the

ability to absorb high impact at the expense of durability) or titanium (for a

combination of lightness with strength, at higher cost) 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. Connecting rods,

especially in racing engines, may be called "billet" rods, if they are machined out of a

solid billet of metal, rather than being cast or forged.

Problems

Stress and failure

Failure of a connecting rod is one of the most common causes of catastrophic

engine failure. The 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 square of the engine speed increase. 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 over-revving of the engine. Re-use of rod bolts is a common

practice as long as the bolts meet manufacturer specifications. 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.

Objectives of study case

A part from the problem mention above, we made a study case to tackle one

of the problems and to relate it in Finite Element Method. The problem that we want

to prove is ‘what is the critical point/stress at connecting rod when applied some

load in it.’ No hard and fast rules can be given to arrive at a satisfactory connecting

rod life. Each case must be painstakingly investigated, the cause or causes isolated

and remedial action taken.

To comply what we have learn in subject Finite Element Method , we used a FEMAP

software when doing the analysis.

GEOMETRY, LOADING AND BOUNDARY CONDITIONS

Figure 1: Geometry of solid connecting rodTotal Nodes : 11161

Total Elements : 6075

Figure 2: Applied load at the top of connecting rod @ 3895N

Figure 3: Constraint at the bottom of connecting rod

Technical Specification

1) Bore in bearing for piston

pin (new)2.1820 to 2.1830 in. (55.423 to 55.449 mm)

Maximum permissible clearance between

bearing and piston pin (worn) 003 in. (0.08 mm)

2) Bore in connecting rod for bearing, with nuts tight to specifications

4.0748 .0005 in. (103.500 + 0.013 mm)

3) Distance between center of bearings 10.300 + .002 in. (261.62 0.05 mm)

4) Diameter of piston pin(new) 1.9998 + .0002 in. (50.795 + 0.005 mm)

5) Bore in bearing for crankshaft  3.8236 to 2.8258 in. (97.119 to 97.175 mm)

Clearance between bearing and crankshaft new

0028 to .0066 in. (0.071 to 0.168 mm)

Maximum permissible clearance between bearing

and crankshaft (worn) 010 in. (0.25 mm)

6) Torque on nut for connecting rod:

a. Put engine oil on threads and nut seat.

b. Tighten both nuts to 60 + 6 lb. ft. (82 + 8 N.m)

Mark each nut and end of bolt.

c. Again tighten both nuts (from mark) 120

side clearance between two connecting rods on same crankshaft pin

(new) 011 to .029 in. (0.28 to 0.74 mm

MATERIAL

The connecting rods are most usually made of steel for production engines,

but can be made of T6-2024 and T651-7075 aluminum alloys (for lightness and the

ability to absorb high impact at the expense of durability) or titanium (for a

combination of lightness with strength, at higher cost) 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. Connecting rods,

especially in racing engines, may be called "billet" rods, if they are machined out of a

solid billet of metal, rather than being cast or forged.

RESULT AND DISCUSSION

Figure 4 : Deformed shape

Figure 5 : Higher stress at top

Figure 6 : Wireframe view

Figure 7: Transparent view

Result and Discussion

The Campro engine is the first automotive engine ever developed by the

Malaysian automotive corporation, Proton. The name Campro is short for Cam

Profile. This engine powers the Proton Gen-2, the Proton Satria Neo, the Proton

Waja Campro as well as Proton's future models. The Campro engine is aimed to

show Proton's ability to make their own engines that produces good power output

and meets newer emission standards.

For our Project, we had using a real connecting rod from Cam Pro engine.

The technical specification as provided shows that a maximum torque is 148 Nm at

6000 rpm. From this information we calculated the maximum force that applied at the

top head when the engine was operate. The value of maximum force is 3895 N.

To fulfill our objective of finding critical point/stress at valve when applied some load,

this study will make sure few assumption which includes:

a) No collision occurs between the valve and piston.

b) Power/force produced during the combustion process occur is fixed at all times.

c) There are no foreign objects in the combustion chamber during combustion

process.

d) All of the components installed close to the engine and operate properly.

Our group had used FEMAP software analysis for the components of the connecting

rod. The results obtained showed that the maximum stress based on Von Mises

Theory at Element (ID 5890) is 12.6003 N/m² and the minimum stress at element (ID

5867) is 0.061996 N/m²,while the stress on the other parts is at a safe level. This

means failure might happen if high force applied. The maximum deflection occurs at

node (ID 898) is 8.55923E-9 m and the minimum deflection happen at node (ID 1)

that the value is zero (Constraint).