thermo mechanical analysis of engine valve and …thermo mechanical analysis of engine valve and...

THERMO MECHANICAL ANALYSIS OF ENGINE VALVE AND VALVE SEAT

INSERT BY FINITE ELEMENT METHOD

G.Ragul 1

, Samrat Majumdar 2

, S. Sankar 3, Prasidh E Prakash

4, Dehesinghraja J

5

1 Department of Mechanical Engineering, Budge Budge Institute of Technology, Kolkata, India

[email protected] 2 Department of Mechanical Engineering, Budge Budge Institute of Technology, Kolkata, India

[email protected] 3 Department of Mechanical Engineering, Nehru College of Engineering and Research Centre, Kerala, India

[email protected] 4 Department of Mechanical Engineering, Malabar College of Engineering and Technology, Kerala, India

[email protected] 5 Department of Management & Fashion Technology, DC School of Management & Technology, India

[email protected]

Abstract

In this investigation deals with the stress induced in a valve due to high thermal gradient and high

pressure inside the combustion chamber. To analyze the valve ANSYS has been used as the tool.

A thermal and structural analysis is performed on the valve. In the first stage of analysis the

temperature distribution across the valve is determined. In the second stage this temperature

distribution is transferred on to another element and pressure load was applied on the valve to

determine the displacement distribution in the valve. The above said process will be repeated

for the different valve materials and finally the best material will be suggested for the valve

based on its strength and thermal properties capability.

1. Introduction

Fontanesi, S, Cicalese, G, Tiberi, A, [1] introduced the concept of thermal behaviour of IC engines

of high performance on direct injected of SI engine for sport car, Goli Udaya Kumar, Venkata

Ramesh Mamilla [2] studied the failure of inlet and exhaust valve in different working condition

failure like fatigue, high pressure inside cylinder and due to load impact. [3] Naresh Kr.

Raghuwanshi, Ajay Pandey. et.al, [3] studied the failure of the intake and outlet valves by various

types of failures due to thermal and mechanical effect through various research paper as review

International Journal of Pure and Applied MathematicsVolume 119 No. 16 2018, 821-832ISSN: 1314-3395 (on-line version)url: http://www.acadpubl.eu/hub/Special Issue http://www.acadpubl.eu/hub/

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paper. Ajay Pandey, R. K. Mandloi [4] studied the failure of valve by SEM and also analysed by

the compression and result is by temperature changes the grain size also because more wear of

valve material. Shamsudeen, A; Abdullah, S, et.al, [5] designed and simulation of CNGDI based

on FEA method as the result they improved the stress and displacement analysis, S. Fontanesia M.

Giacopinia [6] in this work studies about the failure in engine around the water jacket, valves,

spark plug and also analysis done in CFD. Baek, H., Lee. Et.al, [7] studied the increase of engine

fuel consumption, knock behaviour and also valve train durability. Ashouri H [8] introduced the

concept of reduce the thermo-mechanical failure by cyclic test under low compressive stress and

also reduce the fatigue crack in the lining region and the life time also calculated by FEM.

Keywords: Thermal and Structural analysis, Exhaust valve, Temperature distribution, FEA,

ANSYS

2. Dimensions of Exhaust Valve

Fig.1 Valve seat

Fig.2 - Dimensions of Exhaust Valve

3. Material Properties

Table: Mechanical Properties of Valve

Properties 21-4N Nimonic 80A Nimonic 105

International Journal of Pure and Applied Mathematics Special Issue

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Modulus of Elasticity 2x105 N/mm

2 2.2x 10

5 N/mm

2 2.2x 10

5 N/mm

2

Thermal Expansion 18.8 x 10 -6

W/m K

14.5 x 10 -6

W/m K 12.2 x 10 -6

W/m K

Thermal Conductivity 14.5 W/m K 13 W/m K 10 W/m K

4. MODELING AND ANALYSIS The assumptions which are made while modeling the process are given below:-

1. The valve material is considered as homogeneous and isotropic.

2. The domain is considered as axis-symmetric.

3. Inertia and body force effects are negligible during the analysis.

4. The analysis is based on pure thermal loading and structural and thus only stress level due to the

above said is done. The analysis does not determine the life of the exhaust valve.

5. The exhaust valve model used is of solid type.

6. The thermal conductivity of the material used for the analysis is uniform throughout.

7. The specific heat of the material used is constant throughout and does not change with

temperature.

8. Under normal operation, when the valve is properly seating at the cam ramp, stresses arising

from seating are quite moderate. They can become very high when the valve train is improperly

engineered so that the valve bounce occurs, or when the engine is over speeded or the valve lash is

improperly set. In this analysis the stresses due to valve seating has been not taken into account

assuming a normal operation.

9. The distortion stresses in a valve arise due to misalignment of valve with the seat. The valve

head must deflect to accommodate to the seat, and this causes bending stresses in the stem. Under

most conditions, gas pressures and spring loads will be sufficient to bring the valve head into

conformity with a mildly distorted seat.

10. The engine considered for the analysis is a medium range engine (500 kW). It is assumed that

it is water cooled.

11. The heat generated inside the chamber is taken away by water chamber around cylinder liner

and in the cylinder head.

12. The temperature of water in the chamber is maintained at 50oC. Heat from valve is lost through

this water only.

13. The valve keeps popping up and down. The analysis has been done for a stationary valve

assuming that the fatigue life of the valve is very high and the stress arising due to that has been

neglected.

5. DEFINITION OF PROBLEM DOMAIN

The sources of stress in an exhaust valve are as follow-

1) Thermal stresses (Temperature gradient)

2) Mechanical stresses (Stress arising from seating, Distortion Stress)

6. Gas pressure and mechanical load


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A medium range engine with rating 500 kW produces around 60-80 bar of pressure and the

temperature inside combustion chamber varies from (800 – 1200) oC. The combustion process for

spark ignition and compression ignition are different. Even the condition inside the chamber is

different for SI and CI engines. The condition here taken is for CI engines. But the same analysis

can be done for SI engines by varying the boundary conditions.

The heat generated inside the chamber is so high that it becomes very important to remove it

continuously. The heat transfer from an engine takes place in following ways -

1. Water cooled - medium and large engines are usually water cooled the range of such engines

varies from 100 hp - 8000 hp.

2. Sodium cooled - this takes place in very large engines.

3. Air cooled - Most of the small engines and some medium engines are air cooled.

The above mentioned stresses induced in the exhaust valve results in valve failure during repeated

gas pressure loading and thermal loading. This could be overcome by changing the valve

materials as stresses induced are influenced by the material of the exhaust valve.

6.1 Creating a Finite Element Model and Mesh

6.1.1 Axisymmetric Model:

Fig.3 Axisymmetric model of Exhaust Valve

6.2 Model with Mesh:


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Fig.4 Dimensional model of Exhaust Valve with mesh

Fig.5 Boundary Conditions

………. (1)

ρ = density

c = specific heat

T = temperature

t = time

Velocity vector for mass transport

Heat flux vector


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The above equation is the first law of thermodynamics applied to a differential control volume. In

case of thermal analysis of the valve there is no transport of mass across the boundary. The

velocity vector term in the equation is zero for this case.

7. Fourier's Law

Fourier's Law is used to relate the heat flux vector to the thermal gradient:

……… (2)

……… (3)

Conductivity in element in x, y, and z

directions. For steady state, the Laplace equation applies,

…….. (4)

Where and are thermal conductivity in x and y directions respectively. The solution to

this equation may be obtained by analytical, numerical, or graphical techniques. The objective of

any heat transfer analysis is usually to predict heat flow or the temperature which results from a

certain heat flow. The solution of above equation will give the temperature in a two-dimensional

body as a function of the two independent space coordinates x and y.

8. RESULTS AND DISCUSSION Thermal analysis of the exhaust valve for different materials such as 21-4N, Nimonic 80A and

Nimonic 105 are carried out. The properties of different exhaust valve materials such as thermal

conductivity, thermal expansion, density, specific heat, young’s modulus are given as input for

the steady state analysis. The boundary conditions at the outer and the inner surfaces are given as

input which has been considered for the specified operating conditions is given as the thermal

load in to the FEA model. The results for the two different exhaust valve materials are given

below. As the analysis carried out was steady state thermal, the results for both the materials are

almost same.

21-4N:


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Fig.6 Thermal Analysis Result – Temperature distribution

Fig.7 Nodal Displacement

Nimonic 80A



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Nimonic 105:



Table.2: Result and Comparison

Material Displacement (mm) of node 2,3


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21-4 N 0.90383 Nimonic 80 A 0.705281 Nimonic 105 0.601797

8.1 Structural Analysis

Static structural analysis of the exhaust valve for different materials such as 21 4N, Nimonic 80A

and Nimonic105A is carried out. The properties of different exhaust valve materials such as

thermal expansion, young’s modulus are given as input for the structural analysis. The outer

surface is constrained which has been given as the mechanical load in to the FEA model. The

results for the three different valve materials are given below. It has been concluded from the

results that among the three materials chosen for the structural analysis, the Nimonic105A are

best as far as stiffness are concerned compared to the other two material as the maximum

displacement in the Nimonic105A is greater than the other two material which is evident in the

figure above.

9. CONCLUSIONS

In this study, the steady state thermal analysis of the exhaust valve for the different

materials such as 21 4N, Nimonic 80A and Nimonic105A have been performed. ANSYS

software is applied to the steady state thermal analysis problem with outer and inner surface

temperature as thermal boundary conditions. To obtain the simulation of thermal behavior

appearing in different valve material, the basic governing equation for the heat conduction is

solved with the initial boundary conditions with thermal conductivity as the property is solved

for the two materials.

Structural analysis for the three materials produces excellent result by treating the problem as

coupled field analysis. From the structural analysis results for all the three valve materials, it’s

been concluded that the displacements values for the Nimonic105A is very less than the values

of other material steel for the same thermal load and Structural loads. It’s evident from the

analysis, the best material for the valve is Nimonic105A as far as thermal and structural behavior

is concerned.

References:

[1] Fontanesi, S, Cicalese, G, Tiberi, A , “Combined In-cylinder / CHT Analyses for the

Accurate Estimation of the Thermal Flow Field of a High Performance Engine for Sport

Car Applications ., "Combined In-cylinder / CHT Analyses for the Accurate Estimation of

the Thermal Flow Field of a High Performance Engine for Sport Car Applications," SAE

Technical Paper, 2013.


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[2] Goli Udaya Kumar, Venkata Ramesh, Mamilla, “Failure analysis of internal

combustion engine valves by using ansys, , American International Journal of Research in

Science, Technology, Engineering & Mathematics, 5(2), December 2013-February 2014,

pp. 169-173.

[3] Naresh Kr. Raghuwanshi, Ajay Pandey, R. K. Mandloi, “Failure Analysis of Internal

Combustion Engine Valves: A Review, International Journal of Innovative Research in

Science, Engineering and Technology Vol. 1, Issue 2, December 2012.

[4] Ajay Pandey, R. K. Mandloi, “Effects of High Temperature on the Microstructure of

Automotive Engine Valves”, Int. Journal of Engineering Research and Applications, Vol.

4, Issue 3 (Version 1), March 2014, pp.122-126.

[5] Shamsudeen, A; Abdullah, S; Ariffin, A K Ali, “design and simulation of a cylinder

head structure for a compressed natural gas direct injection engine”, International Journal

of Automotive and Mechanical Engineering; Kuantan Vol. 9, 2014.

[6] S.Fontanesia, M. Giacopinia, “Numerical investigation of the cavitation damage in the

wet cylinder liner of a high performance motorbike engine”, Engineering Failure Analysis,

Volume 44, September 2014, Pages 408-423.

[7] Baek, H., Lee, S., Han, D., Kim, J, “Development of Valve train System to Improve

Knock Characteristics for Gasoline Engine Fuel Economy”, Development of Valve train

System to Improve Knock Characteristics for Gasoline Engine Fuel Economy, SAE

Technical Paper 2, 2014.

[8] Ashouri H, “Thermo-mechanical analysis of diesel engines cylinder heads using a two-

layer viscoelasticity model with considering viscosity effects”, international journal of

automotive engineering, volume 5 , number 2; page(s) 1026 to 1038, June 2015


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thermo mechanical analysis of engine valve and …thermo mechanical analysis of engine valve and...

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