ÚK-odbor technické diagnostiky

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    New evaluation method for defects propagation in toroidal roller bearings using dominant frequency of acoustic emission
    (Taylor & Francis, 2024-09-05) Mohammad, Housam; Vlašic, František; Maya, Baraah; Shehadeh, Mhd Ali; Mazal, Pavel
    The increased use of roller bearings in recent years has made it vital to develop techniques for Condition Monitoring (CM) of these valuable assets. Toroidal Roller Bearings (TRB) are one of the recent inventions that has revolutionised some industries because of its unique design. In this study, newly produced TRBs were tested using Acoustic Emission (AE), vibration and temperature, on a specially designed test rig. The AE signal was recorded, processed, and analysed using FFT-based methods to transform from the time domain to the frequency domain, and to specify the Dominant Frequency (DF) of each hit in the signal. The result of the analysis was a layout on the time domain of the DFs of all AE hits along with RMSAE and other parameters, this layout was called DF map. The test was divided into three phases, and the DF bands were divided horizontally into three band groups. The aim is to establish a correlation between the phases and DF bands. Knowing the type of defects that are typical for each phase in the test provided insights to what are the DFs of that type. Promising results can be achieved using this measuring method on other types of bearings.
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    Investigation of the Applicability of Acoustic Emission Signals for Adaptive Control in CNC Wood Milling
    (MDPI, 2025-06-13) Dado, Miroslav; Koleda, Peter; Vlašic, František; Salva, Jozef
    The integration of acoustic emission (AE) signals into adaptive control systems for CNC wood milling represents a promising advancement in intelligent manufacturing. This study investigated the feasibility of using AE signals for the real-time monitoring and control of CNC milling processes, focusing on medium-density fiberboard (MDF) as the workpiece material. AE signals were captured using dual-channel sensors during side milling on a five-axis CNC machine, and their characteristics were analyzed across varying spindle speeds and feed rates. The results showed that AE signals were sensitive to changes in machining parameters, with higher spindle speeds and feed rates producing increased signal amplitudes and distinct frequency peaks, indicating enhanced cutting efficiency. The statistical analysis confirmed a significant relationship between AE signal magnitude and cutting conditions. However, limitations related to material variability, sensor configuration, and the narrow range of process parameters restrict the broader applicability of the findings. Despite these constraints, the results support the use of AE signals for adaptive control in wood milling, offering potential benefits such as improved machining efficiency, extended tool life, and predictive maintenance capabilities. Future research should address signal variability, tool wear, and sensor integration to enhance the reliability of AE-based control systems in industrial applications.
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    Acoustic Emission Response to Erosion-Corrosion and Creep Damage in Pipeline Systems
    (Elsevier, 2020-02-19) Nohál, Libor; Mazal, Pavel; Vlašic, František; Svobodová, Marie
    Pipeline system failures confirm that special attention must be paid to the main components of nuclear power plants in particular. One of the significant degradation factors in terms of integrity and residual life of these components is erosion-corrosion in piping systems and creep in high pressure pipelines of thermal power plants. This article deals with analysis of a set of steel samples with different degrees of degradation using acoustic emission method based on detection of elastic-stress waves in a material. Time domain and frequency domain characteristics of acoustic emission signals generated by different creep mechanisms are analyzed. The main task is to find a relationship between crack creation and propagation and acoustic emission response. Part of the solution is also the design and implementation of a diagnostic method for operation monitoring of the deterioration of the high-pressure piping systems at high temperature. The benefit should be a significant reduction in the risk of damage to important components and reduction of the probability of damaging pipe wall integrity potentially sensitive to erosion-corrosion.