In this paper, a control method for a hydraulic loading system of an electromechanical platform based on a fractional-order PID (Proportion-Integration-Differentiation) controller is proposed, which is used to drive the loading system of a mechatronic journal test rig. The mathematical model of the control system is established according to the principle of the electro-hydraulic system. Considering the indetermination of model parameters, the method of parameter identification was used to verify the rationality of the theoretical model. In order to improve the control precision of the hydraulic loading system, the traditional PID controller and fractional-order PID controller are designed by selecting appropriate tuning parameters. Their control performances are analyzed in frequency domain and time domain, respectively. The results show that the fractional-order PID controller has better control effect. By observing the actual control effect of the fractional-order PID controller on the journal test rig, the effectiveness of this control algorithm is verified.

The friction pair coatings are highly susceptible to failure in marine corrosive environments. To enhance their service performance, this study focuses on the friction pairs in the main shaft transmission of offshore wind turbines and investigates the wear and corrosion resistance of different surface treatment processes. A wear theory model is developed based on dynamic changes in the contact area to predict wear under dry friction and corrosive conditions. The results indicate that the Interzinc B coating exhibits the best overall performance in terms of friction, wear, and corrosion resistance. Rough and high-hardness surfaces increase the friction coefficient, while Zn powder and ZnO adhesive not only produce less abrasive debris but also form a micro-nano particle self-lubricating mechanism, reducing surface wear. Compared with the traditional zinc spraying process, the friction coefficient can be increased by 28.4%, while the wear amount is reduced by 76.2%. The release of Zn²⁺ and the oxidation reaction mechanism enhanced the self-healing ability of the passive film, improving anti-corrosion. The maximum error between the finite element analysis of coating wear and the test results is only 6.26%, which verifies the accuracy of the wear theory model and provides guidance for the precise design of wind turbine transmission friction pairs.

In the present paper, the influences of high temperature on the tribological properties of phenolic resin graphite (PRG) sliding against tungsten carbide-nickel (WC-Ni) alloy in ambient air were investigated systematically. Results demonstrated that the antifriction behaviors of PRG was sensitive to high temperature and PRG exhibits ultra-low coefficient of friction (CoF) of about 0.01–0.015. The low CoF is attributed to the formation of graphite tribofilms, which shows different formation processes on the contact interface at different temperatures (room temperature, 200, 300 and 400 °C). These findings provide insight into the formation mechanism of graphite tribofilms, and provide an important basis for improving the tribological properties of graphite-based friction materials and manufacturing new graphite for seal applications.

Wind turbine’s shrink disk (WTSD), as a component of transmission system, plays a crucial role in the wind turbine work. In this study, the matrix expression of combined pressure and interference magnitude has been derived by analyzing the geometry relationship of interference fit of multi-layer cylinder. The mechanic model is built by simplifying WTSD as interference fit of multi-layer cylinder. The reliability model is established on the basis of pressure-strength model, and the formula regarding reliability sensitivity is derived. In terms of the minimum principle on the square sum of reliability sensitivity and the minimum reliability principle, the reliability-based robust design (RBRD) model is built under the multi-objective conditions, and the dynamic reliability model is established on the basis of reliability model, load model, and residual strength model. Dynamic reliability sensitivity formula is deduced, and the dynamic reliability-based robust design (DRBRD) model is established under the multi-objective conditions. The effects of the coefficient of friction, assembly clearance, and yield strength on the reliability of WTSD are analyzed by RBRD and DRBRD methods. Taking a type of WTSD as an example, the calculating results validate that the reliability changes along with interference magnitude. The comparison of results shows that the above methods and Monte Carlo method have the same tendency and approximately agree well. Moreover, the traditional design method and RBRD method are compared. It turned out that RBRD can improve the reliability of WTSD by 47.6%, the reliability-based sensitivity is less than that from the traditional design method, and the robustness is stronger. The experiment verified that the design methods of this study can better meet the operation requirements.