Wear failure analysis based on a new tribo-dynamic-wear coupling model for big-end bearings and heavy-duty engine experiments

Enhancing the durability of heavy-duty engines requires a deeper understanding of wear failure mechanisms in critical big-end bearings. The complex interdependencies among tribology, dynamics, and wear behaviors poses challenges for accurate modeling, and the underlying failure mechanisms remain inadequately understood under demanding operating conditions. This study proposes a novel tribo-dynamic-wear coupling model for big-end bearings that integrates mixed lubrication, multi-friction-pair dynamics, and the transient evolution of wear morphology. A full-scale engine experiment is performed to validate the model's accuracy, and a detailed surface failure analysis offers insights into the wear mechanisms under real-world conditions. The findings reveal a clear wear asymmetry between the upper and lower bearing surfaces, with the upper surface experiencing more severe wear. Additionally, an axial wear gradient is observed, with the test wear depth at the central region approximately 9.10 μm greater than at the edges. These distinct wear patterns are successfully predicted by the proposed model. The primary cause of exacerbated wear is identified as a significant reduction in hydrodynamic lubrication, driven by the combined effects of high load and low speed. This results in the highest transient solid contact force ratio (94.72%) among the three representative conditions (1000 rpm, 1400 rpm, and 1800 rpm at 100% load). Another contributing factor is the concurrent occurrence of multiple wear mechanisms, including abrasive, oxidative, adhesive, and mild fatigue wear.