Thermal Analysis of Different Piston Head Profiles by Using FEM

The objective of this research work is to optimize the stress variations at the top of the piston in real engine conditions. During this pressure analysis on the examined surface of the piston, the thermal behavior is examined. The operating gas pressure, temperature and piston material functions are used as investigation functions. The analyzes carried out showed that the upper part of the piston could be damaged or broken due to the temperature caused by the working conditions, as the replacement of damaged or non-functioning parts is very expensive and usually difficult to obtain. Concave and convex piston profile designed in Solid Work 2023, used to design the piston geometry and for FEM analysis to optimize the thermal behavior of the used ANSYS R23.0 piston. Aluminum alloy and gray cast iron material for piston construction. Stress and displacement are analyzed for the piston by applying pressure to it in the structural analysis. By observing the results of the analysis, we can decide whether the piston we are designing is safe or not under the applied load conditions. Heat flow and thermal temperature distribution are analyzed using piston surface temperatures in thermal analysis.


Introduction
Nowadays, automotive components are in high demand due to the increasing use of automobiles.The increase in demand is due to the improved performance and lower cost of these components.R&D and test engineers must develop critical components as quickly as possible to minimize time to market for new products.This requires understanding new technologies and rapidly adopting new product developments.A piston is a component of reciprocating internal combustion engines.The piston converts the energy of the expanding gases into mechanical energy.The piston slides in the cylinder liner or sleeve.Pistons are generally made of aluminum alloys or cast iron.To prevent combustion gases from passing the piston and minimize friction, each piston is surrounded by several metal rings.These rings act as a seal between the piston and the cylinder wall and also reduce friction by minimizing the contact area between the piston and the cylinder wall.The piston design must be rigid enough to prevent mechanical and thermal deformation and must have sufficient bearing surface to prevent excessive wear.The piston was designed with resistance and temperature considerations in mind.The strength of the pin must be sufficient to resist shear fracture.During combustion, the piston undergoes deformation, and the energy stored in it is a crucial factor in the performance and failure conditions of a piston under static load.The production of Von Misses yield stress can be formulated as Von Misses stress or equivalent tensile stress; A scalar stress value can be calculated from the stress tensor.

a) Fundamental of Piston
A piston is a cylindrical metal element that moves back and forth within the cylinder and applies force to the fluid in the cylinder.The pistons have outer rings that prevent oil from entering the combustion chamber and fuel and air from escaping from the oil.Most pistons mounted in a cylinder are equipped with piston rings.There are typically two spring-loaded compression rings that act as a seal between the piston and the cylinder wall, as well as one or more oil control rings below the compression rings.The top of the piston may be flat, curved or otherwise shaped.Pistons can be made by forging or casting processes.The piston profile is usually rounded but can vary.Figure 1 shows the structure of the piston engine.The piston is the main element of a piston machine and pneumatic-hydraulic systems.

Piston Design
The piston is designed according to the procedure and specification which are given in machine design and data reference books.

Finite Element Analysis
To perform a finite element study of the piston when gas pressure is applied to it, a structural study is performed using ANSYS Workbench R23.0.In this phase the examination of the piston is static and linear.When small changes in stiffness occur, there is no change in the direction of loading, the materials remain in the linear flexible region, and deformations and mineral stresses appear.The piston model is designed in Solid Work 2023 and saved in this file as *.igs, then imported into ANSYS Workbench.
The experimental piston model was analyzed by ANSYS, which is linked to the commercially used engineering simulation software package, providing a comprehensive assembly that expands the entire variety of physics and gives the right to use in almost various fields of engineering applications requiring a design method.The software package uses its own tools to put a virtual product through a rigorous testing process, such as testing a piston model under various loading conditions, before it becomes an extraordinary object.

Material properties of piston material
Piston analysis performed by using Aluminum alloy and Grey cast iron alloy as the piston material.
Composition of Aluminum alloy and Grey cast iron alloy grade is shown in Table 2.

Results and Discussion a)
Analyzing the model in ANSYS: After designing the model in solid work, IGS FILE has been converted to IGES format.This configuration allows the design to be compatible in the ANSYS software.After importing the design in ANSYS, the process of analysis begins Meshing the model: Mathematically, the piston model to be examined is decomposed into a network of finite-dimensional elements of simple shape.It is assumed that the displacement difference within each component is calculated using simple polynomial profile functions and nodal displacements.Strain and stress equations are created using unknown nodal displacements.From there, the balance equations are assembled into a matrix form that can be easily programmed.

c)
Boundary conditions for analysis of S.I. engine piston using ANSYS After the piston is meshed, we need to apply the suitable boundary condition under which the thermal Analysis will be performed After solution processing, the contours of total strain and equivalent elastic strain are recorded in the static structural analysis.On the other hand, in the transient thermal analysis, the temperature and total heat flux were present.These structural and thermal analysis results are obtained for concave (cup) and convex (dome) pistons.

Conclusion
The piston plays an important role in engine performance; The piston material is made by changing the resistance of the piston.As expected, for both materials the highest force intensity is recorded in the elastic band.It got the maximum displacement on top of the aluminum alloy and gray cast iron piston.The higher maximum force in the piston temperature is due to the thermal conductivity of the material, and the maximum heat flux is absorbed in both piston materials.Therefore, in-depth research can be carried out using advanced materials and various analysis methods and tools.In the designs for which the analyzes are performed, the total stresses and strains observed in the concave-shaped piston are greater than those observed in the convex-shaped piston.This demonstrates the use of hollow or coppershaped pistons in internal combustion engines using diesel in furnaces and large engines.
From the above study it is concluded that the total heat flux in the aluminum alloy hollow piston was 10.64W/mm 2 and the minimum temperature on the surface of the hollow piston was 154.390°C.In this analysis, it is concluded that the hollow piston type has better thermal properties.Therefore, the experimental results show that the hollow piston head has better thermal properties to design the piston according to the thermal conditions of the material.The analysis performed is presented in Ansys Analysis R23.0.These results are based on the finite element method.Therefore, a more in-depth investigation can be carried out using advanced materials and various analysis methods and tools.

Figure 1 :
Schematic Diagram of Piston

Figure 2 :
Drawings of the Piston