 Open Access
 Total Downloads : 637
 Authors : Ajay Raj Singh, Dr. Pushpendra Kumar Sharma
 Paper ID : IJERTV2IS110932
 Volume & Issue : Volume 02, Issue 11 (November 2013)
 Published (First Online): 23112013
 ISSN (Online) : 22780181
 Publisher Name : IJERT
 License: This work is licensed under a Creative Commons Attribution 4.0 International License
Design and Analysis of Reinforced Aluminium AlloyAMC225_{XE} Connecting Rod using FEA
Design and Analysis of Reinforced Aluminium AlloyAMC225XE Connecting Rod using FEA
Ajay Raj Singp
Assistant Professor
Bansal Institute of Research and Technology, Bhopal
Abstract
The connecting rod forms an integral part of an internal combustion engine. The connecting rod is the link between the piston and the crankshaft. Its primary function is to transmit the push and pull from the piston pin to the crank pin, thus converting the reciprocating motion of the piston into rotary motion of the crank.
This paper focuses on the design and analysis of connecting rod using a novel material i.e. reinforced aluminium alloy AMC225XE by finite element analysis. This paper illustrates the procedure for analytical design of aluminium alloy AMC225XE connecting rod using specifications of four stroke single cylinder engine of Bajaj Kawasaki motorcycle. This work predicts the maximum stress and critical region on the aluminium alloy connecting rod using FEA. The theoretical and experimental values of stress are determined and compared. Thereafter, from the results of stress analysis, the critical area of concentrated stress for appropriate modifications is located. Static stress analysis is performed by using ANSYS 12.1.
Keywords: Connecting rod, Reinforced Aluminium Alloy AMC225XE, Static stress, Load, Big end, Small end, ANSYS 12.1

Introduction
Fig 1.1 Connecting Rod
Dr. Pushpendra Kumar Sharma2
Head, Department of Mechanical
Engineering NRI Institute of Science and Technology,
Bhopal
The function of connecting rod is to transmit the thrust of the piston to the crank shaft, and as the result the reciprocating motion of the piston is translated into rotational motion of the crank shaft. Connecting rod has three main zones: the piston pin end, the center shank and the big end. The piston pin end is the small end, the crank end is the big end and the center shank is of I cross section. The connecting rods are subjected to a complex state of loading therefore, durability of this component is of critical importance. Due to these factors, the connecting rod has been the topic of research for different aspects such as production technology, materials, stress analysis etc.
This analysis used the maximum load which was measured theoretically and the maximum stresses at variable loads are found experimentally which suggests the reduction of the inertia load of the connecting rod mass. Connecting rods must have the highest possible rigidity at the lowest weight.
In modern automotive internal combustion engine, the connecting rods are most usually made of aluminium and steel. In high performance engines such as two wheelers the connecting rod is mostly made of aluminium alloys due to high strength to weight ratio. Besides its lower density, it has a high resistance to corrosion under the majority of service conditions. In this paper, for the designing of the connecting rod the specifications of the Bajaj Kawasaki motorcycle and mechanical properties of AMC225XE are used.
AMC225XE is a high grade aluminium alloy (AA2124) reinforced with 25% by volume of ultrafine particles of silicon carbide. It is manufactured by a
special powder metallurgy route using a proprietary highenergy mixing process which ensures excellent particle distribution and enhances mechanical properties. Powder metallurgy and mechanical alloying techniques are used to combine the aluminium alloy (AA2124) matrix with fine (23 micron) Silicon Carbide (SiC) particles. Process conditions are controlled to produce an even distribution of these particles, whilst maintaining the purity of the matrix alloy. Powder is compacted to fully dense billet by hot isostatic compaction. Billets are available for direct manufacture to component or for fabrication by forging, extrusion or rolling techniques. Selection of the process route depends on property requirements, component shape and the resulting process cost.
After getting dimensions of the different parts of the connecting rod, modelling is done on the ANSYS
12.1. The idea behind finite element analysis is to divide a model connecting rod into a fixed finite number of elements. The ANSYS 12.1 generates and predicts the overall stiffness of the entire connecting rod.

Characterization of Material
The material chosen for this work is Reinforced Aluminium Alloy AMC225XE for an internal combustion engine connecting rod.
The key benefits of AMC225XE for structural applications include:

Weight saving

Increased component stiffness

High fatigue resistance.
Fig 1.2 Modulus to weight ratio
Table 1.1 shows the relevant mechanical and thermal properties of Reinforced Aluminium Alloy AMC225XE.
PARAMETERS
VALUES
Elastic Modulus
115 GPa
Ultimate Tensile Strength
650 MPa
0.2% Yield Strength
480 MPa
Poissons Ratio
0.3
Thermal Conductivity
150 W/m/oC
Density
2.88 g/cm3
Table 1.1 Typical Properties of AMC225XE


Engine Specifications
The engine used for this work is a single cylinder four stroke air cooled type Bajaj Kawasaki petrol engine. The engine specifications are given in Table 1.2.
PARAMETERS
VALUES
Engine Type
Four stroke, Petrol engine
Induction
Air cooled type
Number of cylinders
Single cylinder
Bore
51 mm
Stroke
48.8 mm
Length of connecting rod
97.6 mm
Displacement volume
99.27 cm3
Compression ratio
8.4
Maximum power
6.03 KW at 7500 rpm
Maximum Torque
8.05 Nm at 5500 rpm
Number of revolutions/cycle
2
Table 1.2 Engine Specifications


Problem Formulation
The connecting rod is one of the most critical components of an engine. Therefore, it must be designed to withstand from damage that is caused due to high pressure of combustion process. The objective of the present work is to design and analysis of connecting rod made of Reinforced Aluminium Alloy AMC225XE under service conditions of Bajaj Kawasaki petrol engine. After generating the dimensions through analytical design the accurate Finite Element Model is generated and analysis is done by ANSYS to calculate the critical stresses and total deformation by considering the gas pressure. The different loading conditions were applied at one end i.e. small end and the big end is kept fixed. The stresses are calculated theoretically and found out numerically by FEM.

Methodology

Analytical design of connecting rod using specifications of Bajaj Kawasaki petrol engine.

Creation of 3D model of connecting rod using ANSYS.

Meshing of 3D model using ANSYS.

Analysis of connecting rod using static stress analysis method.
 Determination of the theoretical stresses at small end and big end of the connecting rod.

Determination of stresses at different loading conditions experimentally using FEM.

Analytical Design
The connecting rod is subjected to axial compressive force equal to maximum gas load on the piston. Therefore the connecting rod is designed as a column or a strut. The buckling of the connecting rod is in two planes: plane of motion and a plane perpendicular to the plane of motion.
Let
Mechanical efficiency of the engine () = 80 %. = Brake power (B.P)
Indicating power (I.P)
Therefore, I.P = B.P = 6.2 = 7.75 KW
0.8
Also, I.P = P x A1 x L1 x N
I.P = P x D2 x L x N 4
Substituting the values from Table 1.2, we have 7.75 x 1000 = P x (0.051)2 x (0.0488) x (5000)
4 2 x 60
So, P = 18.66 x 105 N/m2 or P = 1.866 MPa
Force on the connecting rod is given by
W = P x D2 = 1.866 x (51)2 = 3811.903 N 4 4
Then the buckling load is
WB = W x F.O.S = 3811.903 x 5 = 19059.52 N
A = cross sectional area of connecting rod (mm2). L = length of the connecting rod (mm).
c= compressive yield stress (MPa).
Ixx and Iyy = moment of inertia of the section about xaxis and yaxis respectively (mm4).
Kxx and Kyy = radius of gyration of the section
about xaxis and y axis respectively (mm).
t = thickness of flange & web of the section (mm). B = 4t = width of section (mm).
H = 5t = height of section (mm). A1 = area of piston (mm2).
D = diameter of the piston (mm). L1 = stroke length (mm).
WB = buckling load (N).
H1 = height at the small end (piston end) (mm). H2 = height at the big end (crank end) (mm).
P = indicating pressure (N/mm2). N = number of revolutions (rpm).
F.O.S = factor of safety = 5
W = force on the connecting rod (N).
If a connecting rod is designed in such a way that it is equally resistant to buckling in either plane then
Ixx = 4Iyy

The standard dimension of I SECTION.
Fig. 3.1 Standard dimension of connecting rod
Area of section A = 2(4t x t) + (5t 2t) x t = 11 tÂ² MI of section about xaxis
Ixx = 1 (4t) (5t)3 1 (4t t) (5t 2t)3 = 1 (500t4 81t4) 12 12 12
= (419) t4
12
KXX2 = IXX = (419 t4 /12) = 3.17 t2 A (1/11t2)
KXX = 1.78 t
MI of section about y axis:
IYY = 2 x 1 (t) (4t)3 + 1 (5t 2t) (t)3 = 1 (128t4 + 3t4) 12 12 12
= (131) t4
12
KYY2 = IYY = (131 t4/12) = 0.992 t2 A (1/11 t2)
KYY = 0.995 t
Therefore, IXX = (419 t4/12) = 419 = 3.2
IYY (131 t4/12) 131
Hence, 3.2 IYY = IXX
WB = C x A .
1 + a (L/KXX )2
19059.52 = 480 x 11 t2 .
1 + (1/7500) (97.6/1.78 t)2
On solving the above equation, we get t = 2.17 mm.
B = 4t = 8.68 mm. H = 5t = 10.85 mm.
Thickness for web: t = 2.17 mm. Thickness for flanges: t = 2.17 mm.
Dimension of middle of I Section of connecting rod H = 10.85 mm
Dimension of small end of I Section of connecting rod: H1 = 0.85 x H = 9.22 mm.
Dimension of big end of I Section of connecting rod: H2 = 1.2 x H = 13.02 mm.

Dimensions of connecting rod at piston side and crank side

The force acting on the piston side is given by W = dp lp (pb)p
Where dp = diameter of the piston pin (mm). lp = length of the piston pin (mm).
(pb)p = allowable bearing pressure for the piston pin bush (N/mm2) = 12.5 MPa.
(lp/dp) = 2.
Hence, 3911.903 = 2 dp x 12.5 dp = 12.35 mm.
2
2
And lp = 2 x 12.35 = 24.7 mm.
Inner diameter of the connecting rod at the small end: dsi = 1.25 x dp = 15.44 mm.
Outer diameter of the connecting rod at the small end: dso = 1.65 x dp = 20.38 mm.
The force acting on the crank side is given by W = dc lc (pb)c
Where dc = diameter of the crank pin (mm). lc = length of the crank pin (mm).
(pb )c = allowable bearing pressure for the crank pin bush (N/mm2) = 10 MPa.
(lc /dc) = 1.5.
Hence, 3811.9 = 1.5 dc2 x 10 dc = 16 mm
And lc = 1.5 x 16 = 24 mm.
Inner diameter of the connecting rod at the big end: dci = 2.03 x dc = 32.42 mm.
Outer diameter of the connecting rod at the big end: dco = 2.68 x dc = 42.8 mm.

Creation of 3D model of connecting rod.
The 3D model geometry is developed in ANSYS
12.1. Various dimensions of the connecting rod are taken from the above analytical design parameters. The finite element model of connecting rod is developed using ANSYS 12.1 modelling tool.
Figure 3.2 3D model of connecting rod

Meshing of 3D model of connecting rod
The 3D 8 node solid elements SOLID185 is applied to mesh the whole structure. A preliminary mesh convergence analysis showed that this level of mesh refinement was adequate to perform linear static structural analysis of the model. The meshing is shown in the figure below.
Fig 3.3 Meshing of 3D model

Static Linear Analysis
The stresses and deformation are determined using Structural Static Linear method. The big end is kept fixed and the gas pressure is applied at the small end of the connecting rod. The maximum and minimum values of stress and deformation are recorded.
Fig. 3.4(a) Static Stress determination
Fig. 3.4(b) Deformation determination

Determination of theoretical stresses at small and big end of the connecting rod
For calculating the value of stresses, the load is varied from 100 % to 225 % of the mean calculated load with a target value of the mean induced stress.
For small end = W .
x dsi x lp
At 100 % load, W = 3811.09 N, Hence, = 3.19 MPa.
Similarly, stress at small end can be calculated at different loading conditions.
For big end
= W .
x dci x lc
At 100 % load, W = 3811.09 N, Hence = 0.62 MPa.
Similarly, stress at big end can be calculated at different loading conditions.

Determination of stresses at different loading conditions experimentally.
The connecting rod is analysed by two methods i.e. theoretically and experimentally. The results obtained by the two methods are compared at two critical areas of the connecting rods where it is likely to fail. The two areas where the results are compared are at the small end and the big end.
In this work, a load variation analysis is performed for the reinforced aluminium alloy AMC225XE material model. The load is varied from 100 % to 225 % of the mean calculated load with a target value of the mean induced stress being equal to the compressive yield strength of the material.

(b)




Results and Discussion
The connecting rod is designed and modelled using ANSYS 12.1. The values of stress are determined theoretically and experimentally and recorded in Table 4.1.
LOAD (N)
STRESS (MPa)
FOR SMALL END
FOR BIG END
THEO
EXP
THEO
EXP
3811.09
3.19
2.96
0.62
0.5
4764.87
3.87
3.25
1.95
1.1
5717.85
4.79
4.59
2.28
1.3
6670.83
5.58
5.40
2.76
1.5
7623.80
6.56
5.90
3.15
1.7
8576.78
7.39
7.44
3.55
1.9
LOAD (N)
FOR SMALL END
FOR BIG END
THEO
EXP
THEO
EXP
3811.09
3.19
2.96
0.62
0.5
4764.87
3.87
3.25
1.95
1.1
5717.85
4.79
4.59
2.28
1.3
6670.83
5.58
5.40
2.76
1.5
7623.80
6.56
5.90
3.15
1.7
8576.78
7.39
7.44
3.55
1.9
(c ) (d)
(e) (f)
Fig 3.6.1 Stress at different Load conditions
(a) 100% (b) 125 % (c) 150 % (d) 175 %
(e) 200 % (f) 225%
(a) (b)
(c) (d)
(e) (e)
Fig 3.6.2 Deformation at different Load conditions (a) 100% (b) 125 % (c) 150 (d) 175 %
(e) 200 % (f) 225%
Table 4.1 Observation Table
The results obtained by the two methods i.e. theoretical and experimental are compared at the critical areas of the connecting rod where the connecting rod is likely to fail. The two areas of the connecting rod where results are compared are small end and big end.
It is found that the stresses at the small end are larger than the stresses at the big end.
The graphs between the load and stress are drawn for both at the small end and the big end. The graph contains plots for both theoretical and experimental values of stress and load which are shown in Fig. 4.1
(a) and (b) (next page).
It is found that both the plots in the graph at small end converge while at the big end they diverge from each other.

Conclusion
The ANSYS analysis of the model designed on the basis of the specifications in this paper determines whether the design is safe or not and further changed can be made in the design considering the reduction in weight. From this, the conclusion can be drawn that the weight at the big end can be reduced so that inertia forces will be minimum.
Newly developed Reinforced Aluminium Alloy AMC225XE enhances higher fatigue resistance in the critical stress region, allow the realization of the thinner structures.
The analysis can be done with other materials of connecting rod for better design and lighter weight.
4000 5000 6000 7000 8000 9000
Load (N)
4000 5000 6000 7000 8000 9000
Load (N)
8
7
6
5
4
3
2
1
0
8
7
6
5
4
3
2
1
0
THEORETICAL
THEORETICAL
EXPERIMENTAL
EXPERIMENTAL
4
3.5
3
2.5
2
1.5
1
0.5
0
4
3.5
3
2.5
2
1.5
1
0.5
0
Stres(MPa)
Stres(MPa)
(a)
Load (N)
Load (N)
References:
(b)
THEORETICAL
THEORETICAL
EXPERIMENTAL
4000
EXPERIMENTAL
4000
5000
5000
6000
6000
7000
7000
8000
8000
9000
9000
Stres(MPa)
Stres(MPa)
Fig 4.1 Graph between Load and Stress (a) at small end (b) at big end.
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