The piston ring is one of the most important parts of a two-stroke marine diesel engine. It is lubricated by a special mode in which the lubricating oil is directly injected into the liner’s inner surface. In this article, taking account of the oil supply, a piston ring lubrication model is developed based on oil mass conservation. The lubrication region of this piston ring–cylinder liner is divided into inlet, core lubrication, and outlet regions, with the oil supply being converted into an oil film. The impact of the width of the core lubrication region on squeezing of the oil is considered. To verify the model, friction force measurements are performed in a reciprocating bench test under fully flooded conditions, and the model is further validated by comparing the minimum oil film thickness with data from the literature. The model is applied to the top ring of a two-stroke marine diesel engine, and the impacts of the oil supply and its design parameters are analyzed.

The flow behavior of the SnSbCu alloy is studied experimentally by the compression tests in the range of the strain rates from 0.0001 to 0.1 s⁻¹ and temperature from 293 to 413 K. Based on the experimental data, three constitutive models including the Johnson–Cook (J–C), modified Zerilli–Armstrong (Z–A), and Arrhenius-type (A-type) models are compared to find out an optimum model to describe the flow behavior of the SnSbCu alloy. The results show that the J–C model could predict the flow behavior of the SnSbCu alloy accurately only at some specific strain rates and temperature near the reference values. The modified Z–A and A-type constitutive models can give better fitting results than the J–C model. While, at high strains, the predictive values of the modified Z–A model have larger errors than those at low strains, which means this model has limitations at high strains. By comparison, the A-type model could predict the experimental results accurately at the whole strain range, which indicates that it is a more suitable choice to describe the flow behavior of the SnSbCu alloy in the focused range of strain rates and temperatures. The work is beneficial to solve the tribological problem of the bearing of the marine engine by integrating the accurate constitutive model into the corresponding numerical model.

In this paper, free vibration and transmission properties of single and composite thin annular plate (TAP) structures are presented by wave approach. The propagation matrix, continuity matrix and reflection matrix are introduced to carry out the analysis. Using the wave approach, natural frequencies of single and composite TAP are calculated theoretically. The results obtained by this method agree well with those calculated by the classical Bessel and Hankel methods. Additionally, transfer matrix is introduced and combined with the boundary conditions to obtain the transmission behaviors of composite multilayer TAP. To thoroughly understand the composite TAP, the influences of thickness, density ratio and radius ratio on natural frequencies are investigated. This study provides very useful information for transverse vibration suppression of TAP structure.