The influence of changes in the rotational speed of the shaft journal slide bearing on the acoustic emission signal

The paper presents preliminary studies of a slide bearing operation by using an acoustic emission. These studies were designed to test the usability of this method for the diagnosis and monitoring of bearings in marine drive system (in particular, stern tube bearing). This paper proposes a method of testing the operating status of the slide bearing using acoustic emission. It discusses the research station, where the study was conducted. The authors paid special attention to the impact of rotation speed of the shaft journal bearing sliding to change some parameters of the acoustic emission signal. The gathered results were analysed and it was evaluated how the rotational speed of the shaft journal affects the individual signal parameters of acoustic emission. Additionally, the sensitivity of the method was evaluated. The article describes: the basics of testing with using the acoustic emission, parameters of the acoustic signal (the acoustic emission burst count, arrival time, duration time, signal amplitude, signal energy and RMS) and the equipment necessary for measurements by using this method. This method, unlike the ultrasonic testing detects only the active wave source, and it is very sensitive to detect changes in the moment when the installation is operating under load. It proposes to use the acoustic emission method to study operational conditions of a slide bearing. Slide bearings are used in many constructions of mechanisms, machines and equipment. They are a strategic element of their design and their improper work leads to the machine damage in a very short period of time, which automatically excludes it from further exploitation. For this reason, the correct assessment of the technical condition of slide bearing and knowledge of the current operating conditions of the slide bearing are extremely important (particularly in the case of bearings in marine propulsion system).