DESIGN OF MACHINE
ELEMENTS
DE-39 Mechatronics
Syndicate – A
Project Report
Modeling and Analysis of the Crankshaft
Group Members:
1. Muhammad Bilal
2. Muhammad Dawood Mustafa
Submitted to: HOD Dr Amir Hamza
INTRODUCTION
Crank shaft is a large component with a complex geometry in the I.C engine, which converts the
reciprocating displacement of the piston to a rotary motion with a four-bar link mechanism.
Crankshaft consisting of shaft parts, two journal bearings and one crankpin bearing. The Shaft
parts which revolve in the main bearings, the crank pins to which the big end of the connecting
rod are connected, the crank arms or webs which connect the crank pins and shaft parts. In
addition, the linear displacement of an engine is not smooth; as the displacement is caused by the
combustion chamber therefore the displacement has sudden shocks. The concept of using
crankshaft is to change these sudden displacements to as smooth rotary output, which is the input
to many devices such as generators, pumps and compressors. It should also be stated that the use
of a flywheel helps in smoothing the shocks.
Crankshaft experiences large forces from gas combustion. This force is applied to the top of the
piston and since the connecting rod connects the piston to the crank shaft, the force will be
transmitted to the crankshaft. The magnitude of the forces depends on many factors which
consist of crank radius, connecting rod dimensions, weight of the connecting rod, piston, piston
rings, and pin. Combustion and inertia forces acting on the crankshaft. 1. Torsional load 2.
Bending load. Crankshaft must be strong enough to take the downward force of the power stroke
without excessive bending, so the reliability and life of the internal combustion engine depend on
the strength of the crankshaft largely.
The crank pin is like a built-in beam with a distributed load along its length that varies with
crank positions. Each web is like a cantilever beam subjected to bending and twisting. 1.
Bending moment which causes tensile and compressive stresses. 2. Twisting moment causes
shear stress.
There are many sources of failure in the engine one of the most common crankshaft failure is
fatigue at the fillet areas due to the bending load causes by the combustion. The moment of
combustion the load from the piston is transmitted to the crankpin, causing a large bending
moment on the entire geometry of the crankshaft. At the root of the fillet areas stress
concentrations exist and these high stress range locations are the points where cyclic loads could
cause fatigue crank initiation leading to fracture.
Fig. 1. A simple Crankshaft
OBJECTIVES:
The main objectives include modelling of crankshaft in SolidWorks Software and static analysis
using ANSYS Workbench Software. To evaluate the Von Misses stress and shear stress.
Modelling:
Solid Modelling was done using SolidWorks software. A front plane was selected for this
purpose. We began by settling proper dimensions for circles and extrudes. After successful
completion of one side, we mirrored it to have full crankshaft.
The detailed steps in form of visual aid are attached below:
Fig. 2. Front Plane
Fig. 3. Circles and extrude dimensions
Fig. 4. Cut Extrude
Fig. 5. A circle is drawn and base extruded
Fig. 6. A new geometry is attached to previous circle
Fig. 7. Cut Extruded
Fig. 8. A new circle is drawn
Fig. 9. Another geometry attached with circle
Fig. 10. A circle is drawn
Fig. 11. Geometry that we first drew is copied here
Fig. 12. Cut extruded
Fig. 13. A circle
Fig. 14. An extruded circle is drawn to provide fixed support later on
Fig. 15. Select geometry to mirror
Fig. 16. A final shape of cranked shaft
ANALYSIS:
Software: ANSYD Workbench
Material: Polished Steel
1. Mesh
Nodes: 5739
Elements: 2844
Fig. 17 Mesh
2. Fixed Supports
Some fixed supports are provided as shown in figure along with two pressures of 3.5MPas.
Fig. 18. Fixed Supports and Pressures
3. Von-Misses Stress
Max Equivalent Stress: 50.6 MPa
Min Equivalent Stress: 0.0017MPa
Fig. 19. Von Misses Stresses
Fig. 20 Max stress at red point shown
4. Shear Stress
Max Shear Stress: 26.945MPa
Min Shear Stress: 0.00096MPa
Fig. 21 Shear Stresses
5. Elastic Strain
Max Elastic Strain: 0.000259mm/mm
Min Elastic Strain: 2.04*10-8
Fig. 22. Elastic Strain
6. Deformation
Max Deformation: 0.3726mm
Min Deformation: 0mm
Fig. 23 Deformation
REFERENCES
[1.] Rincle Garg, Sunil Baghla, “Finite element analysis and optimization of crankshaft”,
International Journal of Engineering and Management Reaserch, vol-2,Issue-6,ISSN: 2250-0758,
Pages:26-31, December 2012.
[2.] C.M Balamurugan, R. Krishnaraj, Dr.M.sakhivel, K.kanthavel, Deepan Marudachalam M.G,
R.Palani, “Computer Aided modelling and optimization of Crankshaft”, International Journal of
scientific and Engineering Reaserach, Vol-2, issue-8, ISSN:2229-5518, August-2011.
[3.] Gu Yingkui, Zhou Zhibo, “Strength Analysis of Diesel Engine Crankshaft Based on PRO/E
and ANSYS”, Third International Conference on Measuring Technology and Mechatronics
Automation, 2011.
[4.] Abhishek choubey, Jamin Brahmbhatt, “Design and Analysis of Crankshaft for single
cylinder 4-stroke engine”, International Journal of Advanced Engineering Reaserch and studies,
vol-1, issue-4, ISSN:2249-8974, pages: 88-90, July-sept 2012.
[5.] R.J Deshbhratar, Y.R Suple, “ Analysis and optimization of Crankshaft using FEM”,
International Journal of Modern Engineering Reasearch, vol-2, issue-5, ISSN:2249-6645,
pages:3086-3088, Sept-Oct 2012.
[6.] Farzin H. Montazersadgh and Ali Fatemi “ Stress Analysis and Optimization of Crankshafts
Subjected to Dynamic Loading”, AISI, August 2007.
