International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 11 Issue: 04 | Apr 2024
p-ISSN: 2395-0072
www.irjet.net
Performance Analysis of Variable Compression Ratio (VCR) of Diesel Engine by Thermal and Fatigue Analysis on Crankshaft Ayush Pandey1, Vikash Dwivedi2 1M.Tech (ME) Scholar, Department of Mechanical Engineering, B. N. College of Engineering & Technology
Lucknow, Uttar Pradesh, India
2 Assistant Professor, Department of Mechanical Engineering, B. N. College of Engineering & Technology Lucknow,
Uttar Pradesh, India ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Internal combustion (IC) diesel engines are
analyzed. The fatigue analysis is carried out to know the factor of safety of the two materials.
established as the main power source for the automobiles and marine vessels due to its superior efficiency over the other engines. The efficiency and life of IC diesel engines are one of the important criteria. An extensive work has been carried out to increase the efficiency of the engine, but only few works has been done in the area of service life of diesel engine. There are various methods to increase the life of engine, like Variable Compression Ratio (V.C.R), different materials of construction, fuel type and fuel quality. Hence, in the present work, an experimental analysis is carried out on Variable Compression Ratio (V.C.R.) diesel engine to measure the engine performance and to determine its optimal compression ratio at a constant speed of 1500rpm. The operational parameters like efficiencies and power adopted are determined at different compression ratios of 16.5, 17.0, 17.5, 18.0 and 18.5 at different loads. Kinematic and Dynamic stress analysis is performed on Piston, Connecting rod and Crankshaft to identify the thermal and structural stresses induced in the VCR engine followed by fatigue analysis to determine its life and factor of safety.
The stress analysis was carried at critical angles of 365 0, 4900, 5400 and 5900 with different loading conditions at a constant compression ratio of 16.5. The results obtained from the structural analysis shows that the stresses induced at the crank pin and bearing supports in the aluminum alloy (7075-T6) are lesser in comparison with AISI E4330 forged steel for different crank angles. For the above crank angles, structural analysis was done using ANSYS and the results show that the stresses and total deformation are more at crank pin than at bearing supports. The analytical and ANSYS results were compared for both the materials. It was found that the variation in the stress value for the Aluminium alloy is less than 1% and for the forged steel is less than 5%. The simulation performed is in very good agreement with the analytical results. The fatigue analysis is conducted for 106 cycles at all critical angles for two materials of the crankshaft. The results shows that the minimum factor of safety these materials is found to be 4.24 for Aluminium alloy and 3.80 for Forged steel. The maximum factor of safety is found to be15.10 for Aluminium alloy and forged steel. The working life of the Al-alloy (17777 hrs.) is more than the forged steel (10233 hrs.), which can lead to lowering the overall cost of the engine. The comparative result shows that the aluminum alloy (7075-T6) exhibits better life than forged steel at 16.5 optimum compression ratio. Hence Alalloy is the best choice for the material construction for the crankshaft.
The experiment is validated through the simulation. The simulation consists of thermal, structural and the thermomechanical analysis. The thermal analysis provides the effect of temperature on the crankshaft, while the structural analysis determines the fatigue life of the crankshaft. Kinematic and dynamic analysis helps in providing the forces on the crankshaft, which are responsible to generate the stress. The forces can be found out by the use of free body diagrams. These forces will continue to change in its magnitude and direction. Hence crankshaft is subjected to the reversal of stresses. It will reduce the life of the engine.
Key Words: Variable Compression Ratio (V.C.R.), Solid works, and ANSYS software, Aluminium alloy, fatigue analysis.
The design of the V.C.R. was carried out at peak pressures and maximum temperatures are obtained through the experiment for different C.R. at different crank angles. For design, optimization and analysis, Solid works, and ANSYS software were used. Different materials were considered for the different components for the optimization and increase of life of the engine like AISI E4340 Forged steel, Aluminum alloy 7075-T6 etc. Total deformation and factor of safety at different crank angles for the two materials are
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1. INTRODUCTION Crankshaft is a large component with a complex geometry in the engine. The crankshaft, connecting rod, and piston constitutes a four-bar slider-crank mechanism, which converts the reciprocating displacement of the piston to a rotary motion with a four-link mechanism. Since the
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