Thermo-structural coupled finite element modeling of engine pistons: A framework for optimized material selection and crown geometry design

Abstract

This study presents a coupled structural-thermal finite element analysis (FEA) framework for the integrated optimization of internal combustion engine piston materials and crown geometries — an approach that, unlike prior studies treating these as isolated design variables, enables direct quantification of their individual contributions under unified boundary conditions. Four materials were evaluated: A2618 aluminum alloy, AL-GHS 1300 aluminum-silicon alloy, AL-SiC aluminum matrix composite, and Ti-6Al-4V titanium alloy. Crown geometry optimization compared bowl head (concave) and dome head (convex) configurations. Simulations were conducted in ANSYS Workbench under realistic conditions derived from a Mercedes-AMG M139 engine (310 kW, 5 MPa peak cylinder pressure). The AL-SiC composite exhibited optimal performance with minimum total deformation (0.0888 mm) and lowest operating temperature (155.02°C), attributed to its superior thermal conductivity (130 W/m·K). Conversely, Ti-6Al-4V showed maximum deformation (0.3692 mm) and highest temperature (198.03°C) due to its extremely low conductivity (7.3 W/m·K). Crown geometry optimization using AL-SiC revealed decisive superiority of the bowl head over the dome head, achieving 72% lower deformation (0.0230 vs 0.0814 mm), 18% lower von Mises stress (125.05 vs 151.86 MPa), a higher safety factor (14.75 vs 13.88), and 13°C cooler operation. Compared to the baseline flat-top design, the bowl head reduced peak stress by 51% and deformation by 74%. A key finding is that crown geometry optimization alone yields performance improvements comparable to advanced material substitution, offering a cost-effective pathway for piston design enhancement in high-performance engines.