No abstract

This paper investigates the mechanical loads resulting from the combustion pressure and dynamic inertia and their effects on the connecting rod of a direct injection turbocharged diesel engine. The main purpose is to enhance the durability of the connecting rod in order to withstand more engine power increase. The distribution of the axial (compressive/tensile) stress, deformation, and safety factors are calculated in order to predict any possible mechanical failure. The finite element routine is used by ANSYS Workbench to analyse the loading on the connecting rod model. The current study is applied to the connecting rod of a 300 hp diesel engine in order to increase the engine power by 17%. The connecting rod operates safely and withstands the applied loads until the power increase reaches 72%. The most stressed points are at the connecting rod shank, while less stressed are experienced at the big end. Calculations show that introducing some changes to the connecting rod geometry may result in decreasing the excessive stresses. These changes include increasing the thickness of the shank cross-section, increasing the fillets radii and slightly reducing the dimensions of the big end in order to maintain the same mass. The new geometry could significantly reduce the maximum stress by 25.5% with an insignificant reduction in the total mass of the connecting rod.

This paper involves simulation of a 4-stroke direct injection heavy duty diesel engine piston made of aluminum silicon alloy to determine its temperature field, stress distribution and deformation at the conditions of upgrading the engine power from 300 HP to 350 HP. Turbocharger is the way used to enhance the engine power from 300 HP to 350 HP beside improving the fuel injection system. When the engine power is upgraded, high temperature and pressure will be developed because the engine will run at high loads. The piston is subjected to the coupled action of the thermal effect due to the transfer of heat from the head to the body and the mechanical effect represented by the combustion pressure and the inertial load due to the important change of direction of the piston in the cylinder bore. This results in producing stresses in the piston and if these stresses exceed the designed values, the failure of the piston is the result. Finite element analysis (FEA) is considered as one of the best numerical tools to model and analyze the physical systems. The three dimensional piston model was developed in Solid-Works and imported into ANSYS software. Finite element analysis is considered Code for preprocessing, loading and post processing. The simulation parameters used in this paper were combustion pressure, inertial effects and temperature. Diesel RK software is used to simulate the thermal analysis of engine cycle at each case of engine power 300 HP and 350 HP. Also, this model included the effect of the heat flow on the piston to overcome the whole area of the piston is used to illustrate the temperature distribution on the total area of the piston. This area divided into piston surface area and sidle area of piston which included the groves of rings (pressure and oil). The heat transfer coefficient is determined in each area of the piston according to the mechanism of heat transfer. Finally, the results of two different piston conditions are compared with each other. The highest temperature appeared at the combustion chamber side which occurred at the edges of the piston top face in direct contact with the hot gases in the radial. The piston deformation value is within a safe margin and below the gap between the piston and the cylinder bore in case of engine power of 350 HP. The highest calculated value of stresses was below the yield stress of the piston material at elevated temperatures and engine brake power of 350 HP. Hence the piston would withstand the induced stresses during work cycles.