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The interaction of temperature variations and viscoelastic deformation is critical in dynamically loaded journal bearings, especially under fluctuating heavy load conditions. Previous studies have not fully explored the coupling of these two factors. Addressing this gap, this research introduces a novel transient mixed lubrication model that simultaneously considers thermal and viscoelastic effects. This model reveals intricate dynamics influencing the lubrication performance of journal bearings. The findings show that the combined impact of thermal and viscoelastic factors significantly alters the amplitude and phase of lubrication performance parameters. Notably, thermal effects tend to decrease oil film pressure while increasing asperity contact pressure, whereas viscoelastic effects enhance the oil film pressure peak and adjust its phase, concurrently reducing asperity contact pressure. Moreover, varying the eccentric speed profoundly influences the interplay between bearing thermal and viscoelastic effects. This study contributes to a deeper understanding of mixed lubrication in journal bearings and provides technical support for more accurate and predictive reliability improvement in complex mechanical systems. [ABSTRACT FROM AUTHOR]

• A dynamic misalignment model coupling rotor dynamics and transient mixed elastohydrodynamic lubrication is proposed. • The dynamic characteristics of dynamically loaded journal bearings have been revealed under dynamic misalignment. • The effects of operating conditions and structural parameters on dynamic misalignment are explored systematically. • Under nonstationary operating conditions, dynamic misalignment exerts an intensified impact on lubrication characteristics. The lubrication characteristics of dynamically loaded journal bearings are significantly affected by misalignments. However, existing research on misalignment primarily focuses on fixed misalignment models, and studies on the nonlinear dynamic response of dynamically loaded bearings under dynamic misalignment are yet to be reported. To address this research gap, this study proposed a dynamic misalignment model coupled with rotor dynamics and transient mixed elastohydrodynamic lubrication. The model comprehensively considers factors such as journal eccentric translation, surface topography, oil film cavitation, and bearing elastic deformation. Upon model validation, numerical simulations are conducted to reveal the single-cycle nonlinear tribological characteristics of dynamically loaded bearings subjected to transient time-varying dynamic loads and time-varying misalignment moments. Based on the dynamic misalignment model, a series of parameter studies were conducted to explore the influence of operating conditions such as load magnitude and rotational speed on lubrication characteristics. The research also evaluated the impact of various structural parameters, including surface roughness, bearing bush thickness, and radial clearance, on the performance of dynamically loaded bearings. The numerical results indicate that the impact of fixed-value misalignment on the performance is highly dependent on the manually set deflection angles. Under light-load and high-speed nonstationary operating conditions, the effect of dynamic misalignment on the lubrication characteristics of dynamically loaded journal bearings was significantly amplified. Furthermore, a smoother surface, thicker bearing bush, and smaller radial clearance intensify dynamic misalignment's influence, compared to fixed-value misalignment, on the transient rough contact behavior at the interface. The findings of this study provide valuable guidance and references for the theoretical analysis and optimization design of dynamically loaded journal bearings. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel transient mixed lubrication model has been developed to simulate the coupling of journal misalignment and bearing viscoelastic deformation. • The bearing performance evolution is revealed under a transient time-varying dynamic load condition. • The coupled influences of misalignment and viscoelastic deformation on the lubrication performance are systematically investigated. • Under high speeds, heavy loads, and large and rapidly changing impact loads, the analysis considering the coupled effects of misalignment and viscoelastic deformation will be more accurate and realistic. Numerous studies on the lubrication characteristics of journal bearings with existing journal misalignment and bearing elastic deformation have demonstrated that both significantly affect the lubrication performance. Recent studies have also indicated that viscoelastic deformation is more useful than elastic deformation for determining the effects of strong impact loads caused by internal combustion engine detonation. However, studies involving the coupled effects of misalignment and viscoelastic deformation have not been reported yet. Therefore, this study proposes a novel transient lubrication model that couples the influences of journal misalignment and bearing viscoelastic deformation, considering the contact surface morphology and oil film cavitation effects. Based on the numerical model, the evolution of lubrication performance under transient time-varying dynamic load was revealed. The coupled influences of misalignment and viscoelastic deformation on the lubrication performance of dynamically loaded journal bearings were systematically investigated. The results show that the coupling of journal misalignment and viscoelastic deformation increases the probability of metal-to-metal contact. The difference in the coupling of misalignment and elastic deformation is exhibited in the distribution, amplitude, and occurrence phases of the performance parameters. Increasing the journal speed and applied load significantly enhances the coupled effects of journal misalignment and viscoelastic deformation on the lubrication performance. Under high speeds, heavy loads, and large and rapidly changing impact loads, the analysis considering the coupled effects of misalignment and viscoelastic deformation will be more accurate and realistic. [Display omitted] [ABSTRACT FROM AUTHOR]

The time lag of bearing deformation caused by viscoelasticity cannot be ignored under time-varying load. This paper proposes a new temporal correlation micro visco-elastohydrodynamic lubrication (T-MVEHD) model. It corrects the calculation method of deformation for dynamically loaded bearings based on the finite element method and viscoelastic constitutive equation and improves the efficiency by uncoupling the stiffness and Reynolds equations. Further, it is applied to the lubrication analysis of internal combustion engine bearing. The simulation results show that the discernment of the new model to the impact is increased by 29.6% than the micro elastohydrodynamic lubrication model. It has better continuity and compatibility when the lubrication state changes and captures the asperity contact of connecting rod bearing 12° in advance. [ABSTRACT FROM AUTHOR]