The Thermal Fatigue Acceleration Test Method, Damage Mechanism, and Life Prediction Model of Diesel Engine Al‐Si Alloy Piston

Diesel engine pistons under thermal cyclic loading and high pressure are prone to thermal fatigue. This study proposes a novel testing method to simulate piston thermal loading, combining experiments and theoretical simulations to analyze the effect of maximum temperature, temperature range, and cycle frequency on fatigue life. The findings indicate that thermal stress accumulation at the edge of the combustion chamber, caused by temperature differences and the mismatch in thermal expansion between Al and Si, leads to microplastic deformation and cracking of the precipitated phases. Increased maximum temperature, temperature range, and frequency significantly reduce fatigue life, with temperature having a dominant impact. A coupled‐factor accelerated life prediction model is developed. Model validation was conducted under experimental conditions of 150°C–380°C and 129 cycles/h, with results showing < 5% relative error against measured data. This work provides a reliable method for piston thermal fatigue life prediction, aiding fatigue‐resistant design and enhancing engine reliability.