Molecular dynamics investigation on micro-cracks behavior of crankshaft and bearing shell

JQ Zhao and JY Li and MC Ji and XZ Song and YQ Zhang and ZY Yuan and JF Li and J Man, MATERIALS TODAY COMMUNICATIONS, 44, 111905 (2025).

DOI: 10.1016/j.mtcomm.2025.111905

During the initial operation of the crankshaft and bearing shell system in a diesel engine, the micro-abrasive that may be generated are subjected to loading by the crankshaft. This phenomenon may induce microscopic cracks on the bearing shell surface, which are challenging to detect through conventional observation methods. Consequently, this presents a substantial challenge in accurately predicting the tribological behavior and performance characteristics of the system. A molecular dynamics approach was used to investigate the microfriction behavior of the crankshaft and the bearing shell. Under the constant load conditions that closely approximates the actual working conditions, the effects of different operating conditions on the tribological characteristics of micro-abrasive were analyzed, such as the load applied to the micro-abrasive, the sliding speed, the particle size, and the initial contact configuration. The tribological characteristics of the bearing shell were evaluated using the substrate surface morphology, substrate wear, substrate temperature variation, system energy variation, average friction of micro-abrasive, and deflection angle. The experimental results indicate that during the engine start-up phase, a velocity exceeding 1.0 m/s, a load greater than 20 nN, and abrasive particle sizes more than twice the dimensions of the surface pits significantly increase the likelihood of the micro-cracks. These findings provide valuable guidelines for optimizing operational parameters to mitigate or prevent adverse operating conditions, consequently minimizing the initiation and propagation of micro-cracks on bearing shell surfaces.

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