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Purpose This paper aims to propose an optimal design of the partial textures in the mixed lubrication regime of the crankpin bearing (CB) to maximize the CB's lubrication efficiency. Design/methodology/approach Based on a hybrid model between the slider-crank-mechanism dynamic and CB lubrication, the square-cylindrical textures (SCT) of partial textures designed on the CB’s mixed lubrication regime are researched. The effect of the density distributions of partial textures on CB’s lubrication efficiency is then evaluated via two indices of increasing the oil film pressure (p) and decreasing the frictional force (Ff) of the CB. The SCT’s geometrical dimensions are then optimized by the genetic algorithm to further improve the CB’s lubrication efficiency. Findings The results show that the SCT of partial textures optimized by the genetic algorithm has an obvious effect on enhancing CB’s lubrication efficiency. Especially, with the CB using the optimal SCT of partial textures (4 × 6), the maximum p is significantly increased by 3.7% and 8.2%, concurrently, the maximum Ff is evidently reduced by 9.5% and 21.6% in comparison with the SCT of partial textures (4 × 6) without optimization and the SCT of full textures (12 × 6) designed throughout the CB’s bearing surface, respectively. Originality/value The application of the optimal SCT of partial textures on the bearing surface not only is simple for the design-manufacturing process and maximizes CB’s lubrication efficiency but also can reduce the machining time, save cost and ensure the durability of the bearing compared to use the full textures designed throughout the CB’s bearing surface.

To decrease the operator’s seat vibration and control the cab’s shaking of the soil compactor, the seat’s control isolation (SCI) added by the QZS structure (SCI-QZS) and the cab’s control isolations (CCI) combined are proposed and investigated. A three-dimensional dynamic model of the soil compactor under the interaction of the tire and drum on the deformable terrain is established to calculate the vibration equation of the soil compactor. The vehicle’s experimental study with the seat’s isolation added by the QZS structure is also given to verify the mathematical model and study result. The isolation efficiency and stability of the SCI-QZS and CCI combined are evaluated based on the root mean square accelerations of the operator’s seat ( aws) and cab’s pitching angle ( a wφc) under the various conditions of the soil compactor. The research shows that with the isolation systems of the soil compactor seat and cab without the QZS structure and control, the operator’s ride comfort and the cab’s shaking are strongly affected under various operating conditions. With the soil compactor using the SCI-QZS and CCI combined, both the operator’s ride comfort and the cab’s shaking are greatly reduced under all the various operating conditions. Especially, the aws and a wφc are remarkably reduced by 67.8% and 59.8% in comparison with the isolation systems of the soil compactor seat and cab without the QZS structure and control. Therefore, the SCI-QZS and CCI combined should be applied on the soil compactor to improve the operator’s ride comfort and control the cab’s shaking of the soil compactors or other off-road vehicles.

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An experimental and theoretical investigation of squeeze-film damper on model rotors and a real jet engine is presented in this paper. It shows that the uncentralized squeeze-film damper, employed to support non-Jeffcott flexible rotors, can be a very effective means of inhibiting the transmission of vibratory forces into the surrounding structure.A design method of uncentralized squeeze-film dampers has been recommended. Theoretical and experimental results have been found in good agreement.