Wyniki wyszukiwania - BazTech

1

Radial internal clearance analysis in ball bearings

Ambrożkiewicz Bartłomiej, Syta Arkadiusz, Meier Nicolas, Litak Grzegorz, Georgiadis Anthimos

Eksploatacja i Niezawodność

|

2021

|

Vol. 23, no. 1

42--54

EN

Radial internal clearance (RIC) is one of the most important parameters influencing on rolling bearing exploitation in mechanical systems. Lifetime of rotary machines strongly depends on a condition of applied rolling elements, thus a study on applied clearance is very important in terms of maintenance and reliability. This paper proposes, a novel approach of studying RIC, based on a nonlinear dynamics method called recurrences. The results are confronted with standard analyses, i.e. statistical condition indicators, Fast Fourier Transform and Continuous Wavelet Transform. The application of the mentioned methods allowed us to find the optimal radial clearance for operating bearings. To ensure precise measurements of the clearance, an automated setup for RIC measurements is applied and next mounted in a plummer block and tested to finally measure vibration acceleration. The proposed methods are useful for a condition monitoring and lifetime prediction of bearings or bearing-based systems in which a proper value of radial clearance is crucial.

2

Impact-based piezoelectric energy harvesting system excited from diesel engine suspension

Caban Jacek, Litak Grzegorz, Ambrożkiewicz Bartłomiej, Gardyński Leszek, Stączek Paweł, Wolszczak Piotr

Applied Computer Science

|

2020

|

Vol. 16, no 3

16--29

EN

Vibration energy harvesting systems are using real ambient sources of vibration excitation. In our paper, we study the dynamical voltage response of the piezoelectric vibrational energy harvesting system (PVEHs) with a mechanical resonator possessing an amplitude limiter. The PVEHs consist of the cantilever beam with a piezoelectric patch. The proposed system was subjected to the inertial excitation from the engine suspension. Impacts of the beam resonator are useful to increase of system’s frequency transition band. The suitable simulations of the resonator and piezoelectric transducer are performed by using measured signal from the engine suspension. Voltage outputs of linear (without amplitude limiter) and nonlinear harvesters were compared indicating better efficiency of the nonlinear design.

3

Diagnostics of Transient States in Hydraulic Pump System with Short Time Fourier Transform

Przystupa Krzysztof, Ambrożkiewicz Bartłomiej, Litak Grzegorz

Advances in Science and Technology. Research Journal

|

2020

|

Vol. 14, no 1

178--183

EN

In hydraulic pump system various states can occur caused by mechanical and physical phenomena. To detect them, the Short Time Fourier Transform (STFT) is applied. This paper will consider an application of STFT to monitor and evaluate hydraulic pump system operation in different states of operation. For measurements of pressure and flow changes in pump, hydraulic tester and Data AcQuisition (DAQ) card was used for evaluation of qualitative and quantitative changes in the system. Results of hydraulic pump’s operation will be shown on Fast Fourier Transform (FFT) charts and STFT spectrograms plots.

4

Periodic trends in two-phase flow through a vertical minichannel: wavelet and multiscale entropy analyses based on digital camera data

Górski Grzegorz, Mosdorf Romuald, Rysak Andrzej, Litak Grzegorz

Acta Mechanica et Automatica

|

2019

|

Vol. 13, no. 1

51--56

EN

By changing the air and water flow relative rates in the two-phase (air-water) flow through a minichannel, we observe aggregation and partitioning of air bubbles and slugs of different sizes. An air bubble arrangement, which show non-periodic and periodic patterns. The spatiotemporal behaviour was recorded by a digital camera. Multiscale entropy analysis is a method of measuring the time series complexity. The main aim of the paper was testing the possibility of implementation of multiscale entropy for two-phase flow patterns classification. For better understanding, the dynamics of the two-phase flow patterns inside the minichannel histograms and wavelet methods were also used. In particular, we found a clear distinction between bubbles and slugs formations in terms of multiscale entropy. On the other hand, the intermediate region was effected by appearance of both forms in non-periodic and periodic sequences. The preliminary results were confirmed by using histograms and wavelets.