Paper Title
Analysis of Mechanical and Thermal Stresses on Connecting Rod/Piston of a Variable Compression Ratio Engine Powered by Biodiesel

Use of alternative fuels in internal combustion engines has become a prime interest for researchers and industrialists as the conventional fuels continue to have higher costs and bigger impact on the environment. However, not too many research works address the analysis of mechanical and thermal stresses in essential components of engines running on alternative fuels. In this work, the fairly new engine technology, Variable Compression Ratio, powered by the alternative fuel biodiesel is considered in terms of the analysis of mechanical and thermal stresses on the connecting rod/piston. Modelling the performance of a biodiesel-powered VCR engine using available software in addition to the modelling the stresses induced on the piston/connecting rod for a variable stroke engine powered by biodiesel using finite element analysis (FEA) software is presented in this work. Experimental work was carried out where biodiesel was injected in a diesel engine and the values of the power and torque were monitored using appropriate measuring devices. Verification of the work was then carried out using special software (Diesel RK) by simulating the same test with similar engine specifications and engine conditions. Temperature and pressure values where then obtained from Diesel RK and applied as boundary conditions in the finite element analysis simulation on the piston and connecting rod. Results showed that using biodiesel fuel increases both the mechanical and thermal stresses in the piston and connecting rod at an earlier stage of the engine stroke due to the characteristics of biodiesel when compared to diesel fuel; this increase in stresses reduces the lifetime of the piston and connecting rod which affects the engine on the long run. Furthermore, an increase in compression ratios results in higher values of stress for both types of fuel. These are significant findings for the industry which indicate that modifications to the engine operation are necessary to reduce stresses on these main engine components. Keywords - Biodiesel, Modelling, Variable Compression Ration, stresses, Finite Element Analysis