The electrostatic sensing technique has been verified to be a viable method for tribo-contact monitoring under laboratory conditions in previous investigations. This paper reports on the evolution of electrostatic monitoring on a real oil-lubricated wind turbine gearbox, using a modified oil-line sensor. In a nominal test and a ramp-up test, features were extracted and the presence of debris can be detected. The permutation entropy was further introduced in an accelerated life test. It can accurately reflect the wear condition of the gearboxes and detect early faults earlier than conventional techniques, which also has a better sensitivity and performance degradation trend than time-domain features.

Electrostatic wear-site sensor (WSS) is one type of the electrostatic sensors based on electrostatic charging phenomenon and has been used in the condition monitoring of tribological systems. With the advantages of high sensitivity and resolution, WSS has been proved to be an effective sensing technique for sliding, rolling, and bearing contacts. However the sensing technique has so far not been widely used in industrial systems due to the difficulties in identifying the exact charge sources and charging mechanisms in a complex tribological system. This paper establishes a mathematical model and presents the results from a simulation of the sensing mechanisms with some useful parameters, which are successfully validated by experimental results. The initial WSS simulation results have led to a better sensor design and application.

In this article, a novel electromagnetic-frictional integrated brake is proposed, and its structure and working principle are introduced. The geometric model and mathematical models of integrated brake were established, and the multi-field coupling mechanism of integrated brake were analyzed. With BYD Qin as a reference vehicle, the boundary conditions of thermal load and force load of integrated brake were determined according to its structure and performance parameters. Based on the COMSOL software, numerical coupling calculations of electric, magnetic, thermal, and solid fields of integrated brake were carried out respectively in the emergency and downhill braking at a constant speed. The axial, circumferential, and radial temperature distributions of integrated brake disc were analyzed respectively, and they were compared with those of the traditional friction brake disc. The analysis results show that the proposed integrated brake can effectively improve the heat fading resistance of automotive brake during emergency and continuous braking. Under the two braking conditions, the temperature rise of friction brake was faster than that of an electromagnetic brake, and the effect of the electromagnetic brake on temperature rise of integrated brake was small.

Electrostatic monitoring is a unique and rapid developing technique applied in the prognostics and health management of the tribological system based on electrostatic charging and sensing phenomenon. It has considerable advantages in condition monitoring of tribo-contacts with high sensitivity and resolution. Unfortunately, the monitoring result can be affected due to the switch of operating conditions that reduces its accuracy. This paper presents a dynamic adaptive fusion approach, moving window local outlier factor based on electrostatic features to overcome the influence. Life cycle experiments of rolling bearings and railcar gearbox were carried out on an electrostatic monitoring platform. The MWLOF method was used to extract and analyze the experimental data, combined with the Pauta criterion to judge wear faults quantitatively, and compare with other feature extraction results. It is verified that the proposed method can overcome the influence of changes in working conditions on the monitoring results, improve the monitoring sensitivity, and provide an accurate reference for friction and wear faults.