The document discusses the design and analysis of a connecting rod using ANSYS. It describes ANSYS as a leading engineering simulation software. It then outlines the steps taken to model, mesh, apply loads to, and analyze a connecting rod design based on specifications for a Honda motorcycle engine. These steps include assigning material properties, creating a CAD model, generating a mesh, applying the expected buckling load, and evaluating stresses, deformation, buckling, and fatigue life. The analysis found an equivalent stress of 252.2 MPa, a safety factor of 2.44 for fatigue, and a buckling load multiplier of 5.598.

1. APPLICATION OF
Design and Analysis of a Connecting Rod

2. : OVERVIEW
• Product of ANSYS Inc., Pennsylvania, US founded in 1970
• Over 40,000 customers (96 of top 100 in the FORTUNE 500 list)
• Acquisitions : CFD Engineering, Airbus, CFX, Century Dynamics, Harvard
Thermal, Fluent Inc. (2006), Apache Design Solutions (2011), etc.
• Static and Dynamic Analysis, Steady-state and Transient Thermal, Fluid Flow
and Modal Analysis
• Extensive array of solvers
• Accurate prediction according to theoretical models

3. DESIGN OF A CONNECTING ROD
• Connection between piston (gudgeon) pin and crank pin
• Converts linear motion to rotary motion
• Subjected to alternating compressive load
• Designed as a short strut against buckling using Rankine’s Formula

4. According to Rankine’s formula :
• Wcr about x-axis =
ߪ𝑐
× 𝐴
1+ܽ[‫ܭ/ܮ‬‫ݔݔ‬]2 [for both ends hinged, l =
L]
• Wcr about y-axis =
ߪ𝑐
× 𝐴
1+ܽ[‫ܭ2/ܮ‬yy]2 [for both ends fixed, l =
L/2]
• For a connecting rod equally strong about both axes, the buckling
loads must be equal. i.e.,
Ixx = 4 x Iyy [∴ 𝐼 = 𝐴×‫ܭ‬2 ]
Generally, Ixx = 3 to 3.5 times Iyy, and the connecting rod is designed to
buckle in X direction.
X
X’
Y
Y’
5
t
4
t
t
In this case, we get :
Ixx = 3.2 x Iyy
I - SECTION

5. PROBLEM SPECIFICATION
Honda 250 cc Specifications:
• Liquid cooled, 4-stroke, single cylinder,
DOHC
• Displacement : 249.67 cc
• Bore x Stroke : 76mm x 55 mm
• Maximum Power : 28.6 BHP@9000 rpm
• Maximum Torque : 23 NM@7500 rpm

6. STEPS IN AN ANALYSIS
Pre -
processing
• Material Assignment
• Creating/Importing CAD Model
• Meshing
• Applying Loads and Fixtures
Solving
• Choosing a solver
• Setting Analysis Parameters (if any)
Post-
processing
• Viewing results
• Interpreting results

7. MATERIAL ASSIGNMENT
Mechanical Properties of Forged Steel

8. CAD MODELLING
Section of the Connecting Rod :
• I – Section
• B x H = 12 x 15 mm
• Thickness of web and flange = 3 mm
Piston End Crank End
Inner Diameter = 16 mm Inner Diameter = 24 mm
Outer Diameter = 24 mm Outer Diameter = 32 mm
Length of the connecting Rod = (2 x stroke length) = 110 mm

9. LOADS AND FIXTURES
According to the formula :
Power = ½ 𝑃 𝑚𝑒𝑝×
𝐿𝐴𝑁
60
• Mean Effective Pressure = 1.14 Mpa
• Considering Maximum Gas Pressure (Pmax) = 2 MPa,
• Buckling Load = Maximum Gas Force (Pmax×Apiston) = 9 kN
• Thickness of Web and Flange is taken 3 mm

10. MESH GENERATION
• Model is divided into ‘Finite Elements’
• Calculations are done at the nodes
Meshing
1-D
• Beams
• Pipes
• Columns
2-D
• Sheet Metal
• Instrument
Panel
3-D
• Engine
block
• Crankshaft
Tetra Penta Brick(Hex) Pyramid

11. MESHING
• Tetra-meshing
• Max. size = 1.8 mm
• Fine Mesh :
• High Accuracy
• More Time
• Coarse Mesh :
• Low Accuracy
• Less Time

12. STRESSES AND DEFORMATION

13. LINEAR BUCKLING
• The connecting rod buckles along
X-X direction as expected.

14. FATIGUE TESTS
• S-N Diagram is constructed
according to the formula :
Sa = σf ’ (2Nf) b
= 1131 (Nf) -0.0711 (MPa)
• Alternating Loading is tested
according to Goodman’s Theory
• Min. Safety Factor = 2.44
• Min. Life = 108 cycles

15. RESULTS
Sl. No. Test Value
1. Equivalent Stress (von Mises) 252.2 MPa
2. Max. Principal Stress 97.73 MPa
3. Normal Stress (X-axis) -60.26 MPa
4. Normal Stress (Y-axis) -222.36 MPa
5. Normal Stress (Z-axis) 97.73 MPa
6. Total Deformation 0.05 mm
7. Fatigue Test : Safety Factor 2.44
8. Linear Buckling : Load Multiplier 5.598