“An Overview and Thermal Analysis of Vehicle Exhaust Gasket”

-----------------------------------------------------------------------------------------------------------------------------------ABSTRACT The Exhaust system is an integral part of the vehicle. To remove the waste gases from the vehicle it came in existence. The performance of engine is mainly affected by exhaust manifold and gasket used because they directly affect the engine stability and control. Generation of back pressure and thermal load restrict to achieve desirable requirement. The protection of the exhaust system from internal and external factors it is necessary to optimize the design of exhaust manifold and gasket because development of crack is more in these two parts.A gasket is designed in this project. For 3D modeling of gasket Creo 4.0 is usedand with the help of ANSYS 17.1the analysis has performed.


INTRODUCTION
The failure of exhaust gasket baffling the engineer for long. The frequently occurring the stress cause the fatigue cracking and plastic deformation of gasket. The Exhaust System is the execration system of vehicle. There are 8 important parts of the exhaust system, they are: 1. Exhaust Manifold 2. Catalytic Converter 3. Resonator 4. Muffler 5. Pipes (Intermediate& Tail Pipe) 6. Gasket 7. Flexible Coupling 8. Oxygen Sensor Since Exhaust parts is subjected to high temperature generated by vehicle engine, due to this thermal load.
To accomplish the required performance as per our convenience, reduction of fatigue failure, wear, thermal stress, cracking in the parts should be avoided. Therefore, proper designing and thermal analysis of vehicle should be done to avoid any future failure for safety purpose.The temperature is decreases form Exhaust manifold to end part of exhaust system i.e., exhaust tip. The high temperature occurs in exhaust manifold which is connected with catalytic converter. The Gasket acts like as seal which connect the exhaust manifold to cylinder head. Thefunction of gasket is to prevent leakage between two mating surfaces under compressed condition and to possess anti-vibration& noise reduction properties.

III. METHODOLOGY
The Steps to be performed for this experiment is as follows:

IV. SELECTION OF MATERIALS
Selecting of gasket material depend on the operating conditions, system requirement, cost and gasket properties. The gasket is mainly classified as:  Table 1 For the exhaust gasket we need to have a high-quality surface sealing, high-temperature and high-pressure resisting material, SinceAll Metallic and Hybrid gaskets fill these requirements, hence they are best to fit for this application. Gold and Rhenium are malleable&stable material but costlier than others that's whyits gasket used only for specific applications. The most common used material for the exhaustgasket is as follows: 1. Steel 2. Copper 3. Inconel 4. Monel 5. Aluminium 6. Titanium….etc.
These materials came into variable grades and can be single or multi-layered. Out of these materials steel and copper is ideal material for exhaust gasket due to easily available and less cost than others. These materials can't be used in its purest form due to higher elasticity. Therefore, their composites forms are used. Table 2 V.

DESIGNING OF EXHAUST GASKET
The design needed where failure starts. Failure is because of higher stress concentrationdue to temperature and pressure. The stress is not removed completely from body but can be reduce by following methodologies: On the basis of system on which gasket is installed, these factors can be fluctuated. Here 3 models are designed with the help of Creo 4.0 software. The thickness and all the dimensions are kept same. The gasket hole cut shape is different in all models i.e. star, circle and oval. Bolt is tightened in this area responsible for stress concentration due to sudden change in shape. .

VI. ANALYSIS OF EXHAUST GASKET
The transientstate thermal analysis and structural analysis has performed on 3 gaskets to calculate stress and deformation. 2 materials have been selected i.e., copper alloy and stainless steel to perform experiment.

TRANSIENT THERMAL ANALYSIS:
The analysis of temperature & fluxes on the system with respect totime is called transient thermal analysis. Temperature changes over time period due to environment and external factors.

STRESS CONCENTRATION DUE TO TEMPERATURE: Fig 4. Meshed Exhaust Gasket
Ansys 17.1 is used for simulation. 3 Boundary Conditions are applied, which are: 1.
Pressure on the upper face (200 MPa).

A. Effect of Temperature
The material gets expand and contract due to change in temperature may result in thermal stress developmentbecause of restriction of freely movement of body. If temperature increase the stress generation also increases, The steps to be perform for analysis is as follows: 1.
Selecting the Material 2.
Meshing The Object 3.
Apply Boundary Conditions 4. Solve Meshing is a set of multiple elements having node. The purpose of meshing is to represent larger body into small discrete cells to perform Finite Element Analysis using mathematical formula for accurate results.

RESULTS:
The result obtained is briefly discussed are as follows:

VIII. CONCLUSION
The Analysis is performed on exhaust gasket by using 2 materials i.e.,Copper Alloy and Stainless Steel, as result obtain, we can conclude the following points: 1. TheHeat transfer in copper is greater than steel 2. Copper deforms more than the steel because coefficient of expansion of copper is higher than steel. 3. The higher stress concentration nearly occurs in hole cuts region. 4. The stress is same for 500℃ and 700℃, thus no significant change of stress due to temperature for defined range. 5. The Stress concentration is higher in oval shape design and lower in Star shape model. 6. The temperature is higher in star shape model due to maximum surface area than other two models.
Thus, we can say that circle shape model is perfect because of low temperature region and low stress concentration. [