In mechanical engineering field, sealing technology is of vital importance for the success of a product. A poor sealing design of a slipper-swash plate friction pair (SSPFP) could lower the reliability of a hydraulic piston pump and lead to the failure of the pump. In this paper, a reliability-based robust design method for the sealing of the SSPFP in hydraulic piston pumps is first established. The matrix expression of the relation between the numerical characteristics of the state function of the SSPFP and the random variables is derived. Methods for calculating the sealing reliability and analyzing the reliability sensitivity of the SSPFP in the hydraulic piston pump are provided. Then, the reliability-based robust design is formulated as a multiobjective design optimization problem to meet the reliability requirements. A numerical example is presented to demonstrate performance of the proposed sealing reliability-based robust design method.

The research of reliability design for impact vibration of hydraulic pressure pipeline systems is still in the primary stage, and the research of quantitative reliability of hydraulic components and system is still incomplete. On the condition of having obtained the numerical characteristics of basic random parameters, several techniques and methods including the probability statistical theory, hydraulic technique and stochastic perturbation method are employed to carry out the reliability design for impact vibration of the hydraulic pressure system. Considering the instantaneous pressure pulse of hydraulic impact in pipeline, the reliability analysis model of hydraulic pipeline system is established, and the reliability-based optimization design method is presented. The proposed method can reflect the inherent reliability of hydraulic pipe system exactly, and the desired result is obtained. The reliability design of hydraulic pipeline system is achieved by computer programs and the reliability design information of hydraulic pipeline system is obtained. This research proposes a reliability design method, which can solve the problem of the reliability-based optimization design for the hydraulic pressure system with impact vibration practically and effectively, and enhance the quantitative research on the reliability design of hydraulic pipeline system. The proposed method has generality for the reliability optimization design of hydraulic pipeline system.

Bearing is one of the most important supporting components in mechanical equipment and its health status has a significant impact on the overall performance of equipment. The remaining useful life (RUL) prediction of bearings is critical in adopting a condition-based maintenance strategy to ensure reliable equipment operation. To accurately predict the RUL of bearings, this paper proposes a two-stage Gaussian process regression (GPR) model, which combines the flexibility of the Gaussian process and the physical mechanism of the Wiener process. Compared with the conventional GPR model, the proposed model can reasonably adapt to the statistical characteristics of bearings degradation and provide more stable predictions. In addition, the paper proposes a new degradation detection approach based on the Euclidean distance to distinguish the two stages of the bearing service life cycle, which considers the global characteristics of bearing degradation and can accurately detect the beginning point of bearing degradation. The experimental results show that the proposed two-stage GPR model can help to improve the precision and accuracy of degradation path tracking and RUL prediction.