A dynamic model of a multisupported sliding bearing rotor system (exhaust camshaft) incorporating journal roundness error is established based on the Lagrange equation. The Timoshenko beam element is employed to simulate the flexibility of the shaft segment, while the cam unit is simplified using an eccentric mass block and modeled through the concentrated mass method. This study investigates the coupling effect of sprocket tension and journal roundness error on the stiffness and damping characteristics of the system. The stiffness and damping variations across different bearing positions are analyzed. Results indicate that the coupling effect leads to local oil film thickness fluctuations, with the maximum film thickness fluctuation increasing by 15%. Sliding bearings near the sprocket end (e.g., J1 and J2) exhibit increased stiffness and damping due to higher loads, whereas those farther from the sprocket end (e.g., J3–J6) experience relatively minor load fluctuations. Although their vibration amplitudes are larger, their stiffness and damping variations remain limited due to the light load, resulting in a weaker influence of sprocket tension on these bearings. A brief discussion of model credibility, limitations, and a practical path to validation is included.
Zhang et al. (2026) studied this question.