This article presents an original method of using elastic waves of acoustic emission (AE) to assess the technical condition of nozzles in marine diesel engines. The developed method makes it possible to detect the early stages of wear by friction of the needle-nozzle pair. The phenomenon of AE and the possibility of its use in evaluating the condition of marine diesel-engine injectors are discussed. Experiments are presented in which the AEs were used to evaluate the condition of both a new injector and an injector where galling of the needle-nozzle pair is developing. The measurements were processed by time-frequency analysis and wavelet transformation.

The article draws attention to the problems of maintaining fuel injection pumps of marine diesel engines in the conditions of the use of residual fuels in which the quality is steadily deteriorating. The analysis of tribological processes occurring in hydraulic precision pairs of fuel injection pumps, such as a barrel-plunger, is presented. Problems occurring regarding the operation of injection pumps and the possibilities of their avoidance on board are discussed. The means of condition monitoring, including the application of thermography methods, are characterized. The authors have done research concerning diagnosing injection systems of high and medium power engines by using acoustic emission (AE) signals. The experiment results obtained with the use of acoustic emission and wavelet analysis confirmed the dependency of the frequency components contained in the acoustic emission signal on the condition state of the injector pumps’ tribological pair.

The method of elastic wave propagation was applied to detect defects in composite castings (ingots). If a defect occurs, which is detected by the radiography, elastic wave propagation changes locally, i.e. causes disturbance of elastic wave propagation. Methods of signal analysis based on wavelet decomposition were used. Calculations related with wavelet analysis were made in the MATLAB environment using standard Wavelet Toolbox functions.Keywords: acoustic emission, wavelet transform, quality of composite castings Wykorzystano metodę badań bazującą na propagacji fal sprężystych do wykrywania wad odlewów kompozytowych. Poddano obserwacji lokalne zmiany propagacji fali sprężystej podczas analizowania defektów, których występowanie potwierdzono za pomocą defektoskopii radiologicznej. Zastosowano metody analizy sygnałów oparte na dekompozycji falkowej. Obliczenie transformat falkowych wykonano w środowisku MATLAB z wykorzystaniem standardowych funkcji Wavelet Toolbox.

The article presents selected problems related to an analysis of damage to wind turbine planetary gear. It is the most vital element installed in wind turbines, affecting the operational costs (prolonged downtime), and costs of repairs and servicing including delivery of required components. The authors have analyzed the wear/failure of planetary gear. The process initiating fatigue wear, different from similar devices in other industries, can be easily observed in wind turbine gear. This establishes a specific direction of research into the causes, and early detection of ‘gas spots’ on gear teeth as they seem to trigger fatigue wear.

Due to the increasing number of applications of power semiconductor devices, more and more attention is being paid to diagnostic methods to determine the condition of working semiconductor components. On the basis of the results of experimental research, a correlation can be observed between the transition between the on/off states of a single IGBT transistor in operation and the acoustic signal emitted by it. Acquisition of acoustic emission signals was obtained using a specialized sensor from Vallen. To record the received signal, a high resolution digital oscilloscope was used, which exported the recorded signal to a file, which enabled further digital processing of the acquired signals. The aim of the study was to determine the usefulness of acoustic emission detection methods to determine the possibility of damage to an element based on the recorded acoustic signal.