The document discusses fatigue analysis of internal combustion engine pistons using finite element analysis. It summarizes four research articles that analyze piston design, stress distribution, heat transfer, and fatigue life when subjected to pressure and temperature loads. The articles analyze pistons made of materials like aluminum alloy, cast iron, and aluminum silicon carbide composite. Finite element analysis software like ANSYS and Adams are used to simulate piston behavior under working conditions and optimize design parameters like thickness, stress levels, and fatigue life. The analyses show that aluminum alloy pistons have better thermal conductivity but lower strength compared to cast iron. Material optimization can further improve piston performance.
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Study on fatigue and stress in piston design materials
1. Project title: study on fatigue
and stress in piston design
sattar ghasemi
department of
biosystem engineering
Shahrekord university
2. First article :Design and Analysis of Piston of
Internal Combustion Engine on Different
Materials Using CAE Tool ANSYS
the modern trend is to develop IC Engine of increased power capacity. One of the
design criteria is the endeavor to reduce the structures weight and thus to
reduce fuel consumption
The piston is “Heart” of the engine and its working condition is the worst one
of the key parts of engine in the working environment
Damage mechanisms have different origins and are mainly wear, temperature ,
and fatigue related
The working
condition of piston in an internal combustion is so worst. During the combustion
stroke the fuel get ignited with the help of spark plug. Due to this
combustion of gases in the cylinder the thermal deformation and
mechanical deformation causes piston cracks, tortuosity etc.
3. It is very essential to check out or analyze the stress distribution,
temperature distribution, heat transfer, thermal load, mechanical load in
order to minimize the stress, minimize the thermal stress and different
loads on working condition of the piston .
In this study firstly we draw the piston model in PRO-E software and finally
the piston is analyzed in ANSYS software
Piston is a reciprocating component in an engine which converts the chemical
energy after the burning of fuel into mechanical energy. The purpose of the
piston is to transfer the energy to crankshaft via connecting rod. The piston
ring is used to provide seal between the cylinder and piston. It must
able to work with low friction, high explosive forces and high temperature
around 200℃ to 280℃.The piston is to be strong but its weight should be less
to prevent inertia forces due to reciprocating motion
4. DESIGN CONSIDERATION FOR A
PISTON
1. It should have minimum mass to minimize the inertia forces.
2. It should form an effective gas and oil sealing of the cylinder
3. It should disperse the heat of combustion quickly to the cylinder walls
4. It should have high speed reciprocation without noise
5. It should be of sufficient rigid construction to withstand thermal and
mechanical distortion
6. It should have sufficient support for the piston pin
5. DESIGN PROCEDURE
The design procedure of piston consists of the
following parameters:
1.Thickness of piston head (th)
Grashoff’s formula th=D
3𝑝𝐷2
16𝜎𝑡
Where : 𝜎𝑡: permissible tensile stress for the
material of the piston
D= cylinder bore/outside diameter of the piston
in mm
P= maximum pressure in N/mm²
6. DESIGN PROCEDURE
2.Heat flows through the piston head (H)
the heat flow through the piston head is calculated using the formula:
H= C ∗ HCV ∗ M ∗ BP
th=
𝐻
12.56∗𝐾∗(𝑇𝑐−𝑇𝑒)
H= Heat flow through the piston head
C=Constant heat supplied to engine(C=0.05).
HCV= Higher calorific value of petrol (HCV=47000 KJ/Kg)
M= Mass of fuel used per cycle (M=0.069 Kw/hr)
BP= Brake power (BP=7.5W)
7. DESIGN PROCEDURE
K= Thermal conductivity of material which is 174.15W/mk.
Thermal conductivity is the ability of a material to conduct and transfer
heat
Tc = Temperature at centre of piston head in °C.
Te = Temperature at edges of piston head in °C.
8. DESIGN PROCEDURE
3. Radial Thickness of Ring (t1)
t1=D
3𝑝 𝑤
𝜎𝑡
D = Cylinder bore = 50 mm
Pw= Pressure of gas on the cylinder wall (nearly taken as 0.025 Mpa to
0.042Mpa)
σt = Allowable bending tensile stress (84 Mpa to 112Mpa for cast iron)
9. DESIGN PROCEDURE
4. Axial Thickness of Ring (t2):
The thickness of the rings may be taken as
t2 = 0.7t1 to t1
5. Width of the Top Land (b1):
The width of the top land varies from
b1= th to 1.2 th
6. Width of other Lands (b2):
Width of other ring lands varies from
b2=0.75t2 to 3
10. DESIGN PROCEDURE
7. Maximum Thickness of Barrel (t3):
t3 = 0.03D + b + 4.5
b = radial depth of piston ring groove.
b = t1 + 0.4
8. Piston Wall Thickness Towards the Open End:
t4 = 0.25t3 to 0.35t3
9. Piston Pin:
Load on pin due to bearing pressure = Pb ∗ do ∗ t1
Where, t1= 0.45D
d1 = 0.6do
11. RESULTS OF CALCULATIONS
th = 9.58 mm from 1 and th = 7.3 mm from equation 2
t1 = 1.63 mm
t2 = 1.14 to 1.63 mm
b1 = 7.3 to 8.76 mm
b2 = 1.22 to 3 mm
b = 2.03mm
t4 = 2.01 to 2.81mm
do = 13 mm
d1= 8 mm
With this values the piston was designed in pro/engineer software
12. RESULT AND ANALYSIS
Aluminium 4032
Temperature Distribution:
On the piston head 500℃
is applied and on the
piston walls 300℃ is
applied
13. RESULT AND ANALYSIS
Deformation due to Pressure:
apply the pressure on the
top of the piston of 3Mpa
and Applying the All DOF on
the piston pin rings by
which we can find out the
deflection in piston
16. CONCLUSION
Their structural analysis shows that the maximum stress
intensity is on the bottom surface of the piston crown in all
the materials, but stress Intensity is close to the yield strength of
Al alloy piston. Maximum temperature is found at the centre of
the top surface of the piston crown. This is equal for all
materials. Depending on the thermal conductivity of the
materials, heat transfer rate is found maximum in Al alloy piston.
For the given loading conditions, Al alloy piston is found most
suitable. But when the loading pattern changes, other materials
may be considered. With the advancement in material science,
very light weight materials with good thermal and mechanical
properties can be used for fail safe design of the I.C.Engine. This
will reduce the fuel consumption and protect the environment.
17. Second article : DESIGN AND
ANALYSIS OF AN IC ENGINE PISTON
AND PISTON RINGS BY USING THREE
DIFFERENT MATERIALS
International Journal of Advances in Mechanical and Civil Engineering, ISSN:
2394-2827 Volume-4, Issue-2, Aprl.-2017
http://iraj.in
18. we are taking pulsar 220cc piston dimensions different materials (grey
cast iron, aluminium alloy, AL-SIC) have been selected for structural
and thermal analysis of piston and piston rings. we created pressure
on piston head 13.65Mpa and 19.649N on these three materials,
and we applied temperature 400c on piston crown and 300c on piston
rings.
Design considerations are same to last article
Forces :
The major forces acting on the piston are as follows: Inertia force
caused by the high frequency of reciprocating motion of piston
Friction between the cylinder walls and the piston rings Forces due
to expansion of gases .
19. Static Analysis On Piston
Catia Software is used to
prepare the piston
the model is saved in IGES file
then IGES file is imported to
ANSYS software for the finite
element analysis
the piston pin holes are fully
constrained for all degrees of freedom
(DOF)
21. Thermal analysis on piston
The steady state thermal
analysis is carried out at
maximum temperature
400deg and minimum
temperature 30deg for
the above three various
materials
26. CONCLUSION
From the tables it is concluded that the aluminum silicon carbide graphite (Al-
SiC Graphite) is showing efficient results
Hence Al-SiC-Graphite is preferable among the three applied materials
27. Third article : Design Analysis
and Optimization of Internal
Combustion Engine Piston using
CAE tool ANSYS
Aditya Kumar Gupta Int. Journal of Engineering Research and Applications
ISSN : 2248-9622, Vol. 4, Issue 11(Version - 5), November 2014, pp.04-10
28. The present work has been based on the following objectives:
1. To design an IC engine piston using INVENTOR.
2. To perform the structural and thermal analysis of piston using ANSYS 13.0.
Piston Materials
Generally pistons are made of Al alloy and cast iron. But the Al alloy is more
preferable in comparison of cast iron because of its light weight which
suitable for the reciprocating part. There are some drawbacks of Al alloys
in comparison to cast iron that are the Al alloys are less in strength and in
wearing qualities. The heat conductivity of Al is about of thrice of the
cast iron. Al pistons are made thicker which is necessary for strength in
order to give proper cooling.
29. Design consideration for a Piston: same to last article
Procedure for design of Piston : same to last article
Results of calculations
S.
No. Parameters
Values
1
Length (L) 158mm
2
Bore Diameter(D) 120mm
3
Pressure(p) 2MPa
4
Permissible stress(𝜎𝑡) 90MPa
5
Gas pressure(pw) 0.25MPa
30. Properties of selected material
Material
Piston
of Young's
Modulus
(M Pa)
Poission's
Ratio
Bulk
Modulus
(M Pa)
Shear
Modulus
(M Pa)
Density
(Kgmm-3)
Coefficient
of thermal
expansion
(℃-1)
Al alloy 71000 0.33 69608 26692 2.77×10-6 2.3×10-5
31. Result and Discussion
Before optimization
After the analysis of temperature
distribution the result comes out
that the maximum temperature is on
the piston head and the minimum
temperature is on the piston skirt
32. Total Deflection The deformation occurred into
piston is 0.25483mm.The
deformation in the piston is
given below
33. Equivalent stress (Von- Mises)
Von mises stress is important to calculate the factor of safety by which we
decide that design is safe.
maximum Von-mises stress is 81.636MPa. The Von-Mises stress is become less
than the permissible stress. In
this permissible stress is 90MPa for the Al alloy. By this the design is safe
because factor of safety is greater
than 1. It is very important to calculate to design the piston that the design is
safe or not.
35. Optimization
Optimization is technique to improve the design specifications. There are
some constraints which are consider for optimization of piston they are
1. Maximum Von mises stress<Allowable stress
2. Factor of safety>1
3. Deflection
36. After Optimization
Deflection after optimization
After the optimization the deflection
becomes 0.2687mm from 0.25483mm.By
this the resistance from pressure applied
to piston become increase. The chances of
failure decrease by the optimization
process.
37. Von-Mises stress after optimization
The Von-mises stress becomes
87.875MPa from 81.636MPa
after optimization
38. Design values after optimization
S. No. Parameter Before
Optimization
After
Optimization
Design
Consideration
1 Volume 904370mm3 863980mm3 863980mm3
2 Mass 2.5051 kg 2.3932 kg 2.3932 kg
3 Length 158mm 158mm 158mm
4 Bore Diameter 120mm 120mm 120mm
5 Deflection 0.25483mm 0.2687mm 0.2687mm
6 Von-Mises Stress 81.636MPa 87.875MPa 87.875MPa
7 Factor of Safety 1.102 1.02 1.02
39. conclusion
In this work the main consideration is to optimize the piston with reduction of piston
weight. The material of the piston becomes reduced. Then the optimized result of the
piston obtained. The design become consider as safe when Von-Mises stress is less than
the permissible stress.
The factor of safety becomes greater than one then the design become safe. The factor
of safety after optimization is 1.02 obtained. The permissible stress induced in the piston
is about 81.636Mpa to 87.875MPa
40. Forth article :
DESIGN AND FATIGUE LIFE
ESTIMATION OF DIESEL ENGINE
PISTON USING ANSYS AND FESAFE
International Research Journal of Engineering and Technology (IRJET) e-ISSN:
2395-0056 p-ISSN: 2395-0072 Volume: 04 Issue: 06 | June -2017
www.irjet.net
41. Design consideration for a
Piston: same as last
In this project, the loading cycle applied on the
Diesel engine piston during the motion of the piston
with velocity 6 m/s, also a simple structural analysis
was carried out on the piston by taking peak load
from the ADAMS software.
43. Determination of the Loading Cycle:
In order to apply pressure load on the piston the inertial
loads of the piston were calculated as loading cycles by
using Adams software
The entire engine assembly model was created using Catia
and the assembly
After importing the engine assembly the same AISI 1040 steel
material properties were applied to all the engine
components
model by creating a material set in which the values of
density ρ = 7860 kg/m3, Young’s Modulus E = 205GPa and
Poisson’s ratio υ = 0.3 were entered
44. Determination of the Loading Cycle:
the gravity was defined and the respective joint constraints
were defined for the entire model. The different joints
defined for the engine model in which the revolute joint
specified in the crank was given a motion of 83 deg/sec for
the piston to reach a velocity of 6 m/s.
It can be seen that the maximum inertia force (IF) is 461.64
N for the piston velocity of 6 m/s.
45. Calculation of Total Pressure acting
on the Piston:The total pressure acting on the piston is calculated by subtracting the inertial loads
from the gas pressure loads
for the 100 mm diameter CI engine piston the gas force is taken as 96000 N
Total Force acting on the Piston:
F = Gas Force – Inertia Force
= 96000 – 461.64
F = 95538.36 N
Total Pressure acting on the Piston:
P = Total Force acting on the Piston / Piston Area
= 95538.36 / (π * 502)
= 12.16MPa
46. Stress Distribution on the Piston:
In case of fatigue failure there two important stress that are
to be considered. If the material is ductile in nature and if it
fails when the stain energy reaches above the yield stress of
the material (415 MPa for Piston) then Von Mises stress is
suitable for identifying the vulnerable spots
47. Stress Distribution on the Piston:
Here it can be seen that the
vulnerable red spots is in the
region where its cross
section changes
48. Estimation of Fatigue Life of Piston
without Temperature Factor
Considered
the material was defined as ductile material with Ultimate
Strength ςu = 655MPa, Young’s Modulus E = 205GPa, Poisson’s
ratio υ =0.3 and S-N curve values
the loading cycle was defined based on the load curve
obtained using Adams
Then the algorithm was set to Uniaxial Stress Life Goodman
49. result file was analyzed and it showed a worst life
of 2.184 x 106 cycles