International Journal of Science, Engineering and TechnologyAuthors: Arpita Sunil Kale, Tushar Badgujar
Abstract: The piston is one of the most heavily loaded parts of an internal combustion engine, and its material influences strength, temperature, deformation and reciprocating mass. This paper compares aluminium alloy A2218, AISI 4340 steel and Ti-6Al-4V titanium alloy for the piston of a 50 mm bore, 49.5 mm stroke, 9:1 compression ratio single-cylinder spark-ignition engine running at 7500 rpm. A steady-state axisymmetric thermal model, solved by the finite-volume method, provides the temperature field under combustion heat flux and oil-side cooling. The crown is treated as a clamped circular plate under gas pressure with an added thermal-stress term, and the pin boss as a thick-walled ring. For identical geometry (4 mm crown) the peak crown temperature is 219 °C for A2218, 281 °C for AISI 4340 and 473 °C for Ti-6Al-4V, because thermal conductivity falls from 150 to 44.5 and 6.7 W/m·K. The thermal stress contribution is 19 % of the total stress for aluminium but 53 % for titanium. When the crown is sized for a safety factor of 2, A2218 needs 5.5 mm and gives the lightest piston (87.9 g), against 125.6 g for Ti-6Al-4V (3.5 mm) and 228.3 g for AISI 4340 (4.0 mm). Aluminium is therefore the best choice for this engine, titanium requires a crown thermal strategy, and steel is justified only if its walls can be made much thinner. The results are from a simplified model and are intended as a pre-design comparison to be confirmed by three-dimensional FEA and testing.
DOI: https://doi.org/10.5281/zenodo.24156453
