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Strömbergsson, D., Marklund, P., Berglund, K. & Larsson, P.-E. (2020). Bearing monitoring in the wind turbine drivetrain: A comparative study of the FFT and wavelet transforms. Wind Energy
Öppna denna publikation i ny flik eller fönster >>Bearing monitoring in the wind turbine drivetrain: A comparative study of the FFT and wavelet transforms
2020 (Engelska)Ingår i: Wind Energy, ISSN 1095-4244, E-ISSN 1099-1824Artikel i tidskrift (Refereegranskat) Epub ahead of print
Abstract [en]

Wind turbines are often plagued by premature component failures, with drivetrain bearings being particularly subjected to these failures. To identify failing components, vibration condition monitoring has emerged and grown substantially. The fast Fourier transform (FFT) is the major signal processing method of vibrations. Recently, the wavelet transforms have been used more frequently in bearing vibration research, with one alternative being the discrete wavelet transform (DWT). Here, the low‐frequency component of the signal is repeatedly decomposed into approximative and detailed coefficients using a predefined mother wavelet. An extension to this is the wavelet packet transform (WPT), which decomposes the entire frequency domain and stores the wavelet coefficients in packets. How wavelet transforms and FFT compare regarding fault detection in wind turbine drivetrain bearings has been largely overlooked in literature when applied on field data, with non‐ideal placement of sensors and uncertain parameters influencing the measurements. This study consists of a comprehensive comparison of the FFT, a three‐level DWT, and the WPT when applied on enveloped vibration measurements from two 2.5‐MW wind turbine gearbox bearing failures. The frequency content is compared by calculating a robust condition indicator by summation of the harmonics and shaft speed sidebands of the bearing fault frequencies. Results show a higher performance of the WPT when used as a field vibration measurement analysis tool compared with the FFT as it detects one bearing failure earlier and more clearly, leading to a more stable alarm setting and avoidable, costly false alarms.

Ort, förlag, år, upplaga, sidor
John Wiley & Sons, 2020
Nyckelord
bearing failure, condition monitoring, discrete wavelet transform, wavelet packet transform, wind turbine gearbox bearings
Nationell ämneskategori
Tribologi (ytteknik omfattande friktion, nötning och smörjning)
Forskningsämne
Maskinelement
Identifikatorer
urn:nbn:se:ltu:diva-77861 (URN)10.1002/we.2491 (DOI)000513910600001 ()
Tillgänglig från: 2020-02-27 Skapad: 2020-02-27 Senast uppdaterad: 2020-03-10
Strömbergsson, D., Marklund, P., Berglund, K., Saari, J. & Thomson, A. (2019). Mother wavelet selection in the discrete wavelet transform for condition monitoring of wind turbine drivetrain bearings. Wind Energy, 22(11), 1581-1592
Öppna denna publikation i ny flik eller fönster >>Mother wavelet selection in the discrete wavelet transform for condition monitoring of wind turbine drivetrain bearings
Visa övriga...
2019 (Engelska)Ingår i: Wind Energy, ISSN 1095-4244, E-ISSN 1099-1824, Vol. 22, nr 11, s. 1581-1592Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Although the discrete wavelet transform has been used for diagnosing bearing faults for two decades, most work in this field has been done with test rig data. Since field data starts to be made more available, there is a need to shift into application studies.

The choice of mother wavelet, ie, the predefined shape used to analyse the signal, has previously been investigated with simulated and test rig data without consensus of optimal choice in literature. Common between these investigations is the use of the wavelet coefficients' Shannon entropy to find which mother wavelet can yield the most useful features for condition monitoring.

This study attempts to find the optimal mother wavelet selection using the discrete wavelet transform. Datasets from wind turbine gearbox accelerometers, consisting of enveloped vibration measurements monitoring both healthy and faulty bearings, have been analysed. The bearing fault frequencies' excitation level has been analysed with 130 different mother wavelets, yielding a definitive measure on their performance. Also, the applicability of Shannon entropy as a ranking method of mother wavelets has been investigated.

The results show the discrete wavelet transforms ability to identify faults regardless of mother wavelet used, with the excitation level varying no more than 4%. By analysing the Shannon entropy, broad predictions to the excitation level could be drawn within the mother wavelet families but no direct correlation to the main results. Also, the high computational effort of high order Symlet wavelets, without increased performance, makes them unsuitable.

Ort, förlag, år, upplaga, sidor
John Wiley & Sons, 2019
Nyckelord
bearing failure, condition monitoring, discrete wavelet transform, mother wavelet selection, wind turbine field measurements
Nationell ämneskategori
Annan samhällsbyggnadsteknik Tribologi (ytteknik omfattande friktion, nötning och smörjning)
Forskningsämne
Maskinelement; Drift och underhållsteknik
Identifikatorer
urn:nbn:se:ltu:diva-75777 (URN)10.1002/we.2390 (DOI)000480192400001 ()
Anmärkning

Validerad;2019;Nivå 2;2019-12-06 (johcin)

Tillgänglig från: 2019-08-30 Skapad: 2019-08-30 Senast uppdaterad: 2019-12-06Bibliografiskt granskad
Wu, J., Huang, X., Berglund, K., Lu, X., Feng, X., Larsson, R. & Shi, Y. (2018). CuO nanosheets produced in graphene oxide solution: An excellent anti-wear additive for self-lubricating polymer composites. Composites Science And Technology, 162, 86-92
Öppna denna publikation i ny flik eller fönster >>CuO nanosheets produced in graphene oxide solution: An excellent anti-wear additive for self-lubricating polymer composites
Visa övriga...
2018 (Engelska)Ingår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 162, s. 86-92Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

In the present work, graphene oxide is used as template to produce CuO nanosheets, which solves aggregation and dispersion problems of CuO nanosheets resulting in improved lubricating performance. SEM and AFM studies show that CuO nanosheets are present in fusiform flake shape with a thickness, width and length of around 13, 400 and 1000 nm, respectively. CuO nanosheets were added to the carbon fibers reinforced Polytetrafluoroethylene (CF/PTFE) to study their lubricating performance. It is interesting, from fractured surfaces of composites, to find that CuO nanosheets enhance the interface properties between carbon fibers and PTFE. The wear resistance property of CF/PTFE is remarkably improved after filling CuO nanosheets. For example, the wear rate is reduced by 51% after filling 1.5 wt % CuO nanosheets. The wear resistance improvement effect of CuO nanosheets is much better than that of commercial CuO nanogranules and CuO nanorods. Worn surfaces and counter-surfaces studying indicates that CuO nanosheets can not only prevent the rubbed-off of PTFE or the detachment of CF, but also improve the properties of transfer films, which greatly reduce the adhesive wear and abrasive wear.

Ort, förlag, år, upplaga, sidor
Elsevier, 2018
Nationell ämneskategori
Tribologi (ytteknik omfattande friktion, nötning och smörjning)
Forskningsämne
Maskinelement
Identifikatorer
urn:nbn:se:ltu:diva-68387 (URN)10.1016/j.compscitech.2018.04.020 (DOI)000438180500010 ()2-s2.0-85046114065 (Scopus ID)
Anmärkning

Validerad;2018;Nivå 2;2018-05-09 (andbra)

Tillgänglig från: 2018-04-17 Skapad: 2018-04-17 Senast uppdaterad: 2018-08-09Bibliografiskt granskad
Berglund, K. & Shi, Y. (2017). Friction and Wear of Self-Lubricating Materials for Hydropower Applications under Different Lubricating Conditions. Lubricants, 5(3), Article ID 24.
Öppna denna publikation i ny flik eller fönster >>Friction and Wear of Self-Lubricating Materials for Hydropower Applications under Different Lubricating Conditions
2017 (Engelska)Ingår i: Lubricants, ISSN 2075-4442, Vol. 5, nr 3, artikel-id 24Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Self-lubricating bearings in hydropower applications are often lubricated with water under boundary lubricating conditions. Polyhydric alcohols replacing water have shown the potential to reduce both friction and wear. The objective of this work is, therefore, to evaluate the effect of a polyhydric alcohol-based environmentally-acceptable lubricant (EAL) on the friction and wear of self-lubricating materials for conformal contacts under boundary lubricating conditions. The lubricating properties of four commercially-available self-lubricating bearing materials were investigated under three different lubricating conditions: dry, water and a new polyhydric alcohol-based EAL. Bearing materials include one metallic composite and three polymer composites. A reciprocating motion test rig was used to evaluate the wear and friction properties. Surface analysis was performed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and optical profilometry. Results show that the wear rate for the polymer composites is increased when water is present compared to dry operating conditions. The new polyhydric alcohol-based EAL substantially improves both friction and anti-wear performance of all four self-lubricating bearing materials compared to both dry and water conditions. Surface analysis indicates that the material transfer to the counter-surface is limited when the polyhydric alcohol-based EAL is used.

Ort, förlag, år, upplaga, sidor
MDPI, 2017
Nationell ämneskategori
Tribologi (ytteknik omfattande friktion, nötning och smörjning)
Forskningsämne
Maskinelement
Identifikatorer
urn:nbn:se:ltu:diva-65141 (URN)10.3390/lubricants5030024 (DOI)000410639100005 ()2-s2.0-85029493385 (Scopus ID)
Anmärkning

Validerad; 2017; Nivå 2; 2017-08-16 (andbra)

Tillgänglig från: 2017-08-16 Skapad: 2017-08-16 Senast uppdaterad: 2018-07-10Bibliografiskt granskad
Björling, M., Berglund, K., Spencer, A. & Larsson, R. (2017). The effect of ageing on elastohydrodynamic friction in heavy-duty diesel engine oils. Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, 231(6), 708-715
Öppna denna publikation i ny flik eller fönster >>The effect of ageing on elastohydrodynamic friction in heavy-duty diesel engine oils
2017 (Engelska)Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 231, nr 6, s. 708-715Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

To further improve the efficiency of machine components found in automotive engine systems it is important to understand the friction generation in these components. Modelling and simulation of these components are crucial parts of the development process. Accurate simulation of the friction generated in these machine components is, amongst other things, dependent on realistic lubricant rheology and lubricant properties, where especially the latter may change during ageing of the lubricant. Many modern heavy-duty diesel engines are in operation for several hundred hours before the engine oil is changed. In this work, two engine oils, one 10 W-30 and one 5 W-20, have been aged in full heavy-duty diesel engine bench tests for 400 and 470 hours respectively. This roughly corresponds to the amount of ageing these oils are subjected to between oil drains in field conditions. The aged oils were subjected to a number of oil analyses showing, among other things, a maximum increase in oil viscosity of 12.9% for the 5 W-20 oil and 5.5% for the 10 W-30 oil, which is most likely primarily an effect of evaporation and oxidation. The aged oils were tested in a ball-on-disc test rig under elastohydrodynamic conditions where friction was measured and the performance was compared to fresh samples of the same oils. The results show that there is almost no difference in elastohydrodynamic friction when comparing the aged oils with the fresh oils. These results indicate that it is not necessary to include oil ageing in numerical elastohydrodynamic friction models as long as the oil is changed before the ageing has reached a critical level

Ort, förlag, år, upplaga, sidor
Sage Publications, 2017
Nationell ämneskategori
Tribologi (ytteknik omfattande friktion, nötning och smörjning)
Forskningsämne
Maskinelement
Identifikatorer
urn:nbn:se:ltu:diva-63610 (URN)10.1177/1350650116674848 (DOI)000402067300004 ()2-s2.0-85019744905 (Scopus ID)
Anmärkning

Validerad;2017;Nivå 2;2017-05-30 (andbra)

Tillgänglig från: 2017-05-30 Skapad: 2017-05-30 Senast uppdaterad: 2018-07-10Bibliografiskt granskad
Emadi, M., Berglund, K. & Minami, I. (2016). Does your lubrication system conform to the concept of green chemistry? (ed.). In: (Ed.), : . Paper presented at 20th International Colloquium Tribology : 12/01/2016 - 14/01/2016.
Öppna denna publikation i ny flik eller fönster >>Does your lubrication system conform to the concept of green chemistry?
2016 (Engelska)Konferensbidrag, Enbart muntlig presentation (Övrigt vetenskapligt)
Abstract [en]

We frequently find “EAL” (environmentally acceptable lubricant or relevant such as “environmentally friendly,” “environmentally adapted,” “environmental benign,” “biodegradable,” “ecological,” “green,” in the title and keywords of tribology papers. It intimates "something good for environment" and may catch the readers' attention. However, one might feel unease because the definition of these terms is unclear. These terms are too loosely used with the authors’ satisfaction in most cases. Of course, lubrication engineering contributes to protect global environment by improving energy efficiency and prolonging machine life through reducing friction and wear. In this regard, lubrication itself is definitely one of the “green” technologies. This led a simple question – why adjectives such as “environmental” are used with lubrication? The unrivalled reference book in tribology defines “environmentally friendly lubricants” as “readily biodegradable in nature” [1]. We agree with it, but shall ask "is biodegradability enough for protection of global environment?" This motivated us to propose unambiguous criteria for EAL.

Nationell ämneskategori
Tribologi (ytteknik omfattande friktion, nötning och smörjning)
Forskningsämne
Maskinelement
Identifikatorer
urn:nbn:se:ltu:diva-37718 (URN)bd3f9de3-5403-4279-9f1d-3767acf90726 (Lokalt ID)bd3f9de3-5403-4279-9f1d-3767acf90726 (Arkivnummer)bd3f9de3-5403-4279-9f1d-3767acf90726 (OAI)
Konferens
20th International Colloquium Tribology : 12/01/2016 - 14/01/2016
Tillgänglig från: 2016-10-03 Skapad: 2016-10-03 Senast uppdaterad: 2018-01-14Bibliografiskt granskad
Berglund, K., Emadi, S. & Minami, I. (2016). Lubricant Maintenance Based on Condition Monitoring. In: STLE 2016 Annual Meeting and Exhibition: . Paper presented at 71st STLE Annual Meeting and Exhibition will be held in Las Vegas, Nevada, May 15-19, 2016.
Öppna denna publikation i ny flik eller fönster >>Lubricant Maintenance Based on Condition Monitoring
2016 (Engelska)Ingår i: STLE 2016 Annual Meeting and Exhibition, 2016Konferensbidrag, Muntlig presentation med publicerat abstract (Refereegranskat)
Nationell ämneskategori
Tribologi (ytteknik omfattande friktion, nötning och smörjning)
Forskningsämne
Maskinelement
Identifikatorer
urn:nbn:se:ltu:diva-41893 (URN)
Konferens
71st STLE Annual Meeting and Exhibition will be held in Las Vegas, Nevada, May 15-19, 2016
Tillgänglig från: 2016-10-04 Skapad: 2016-10-04 Senast uppdaterad: 2018-01-14Bibliografiskt granskad
Berglund, K. & Shi, Y. (2016). Performance of self‐lubricating materials for hydropower applications under different lubricating conditions. In: Nordic Symposium on Tribology - NORDTRIB 2016: . Paper presented at 17th Nordic Symposium on Tribology - NORDTRIB 2016, Aulanko, Hämeenlinna, Finland, 14–17 June 2016.
Öppna denna publikation i ny flik eller fönster >>Performance of self‐lubricating materials for hydropower applications under different lubricating conditions
2016 (Engelska)Ingår i: Nordic Symposium on Tribology - NORDTRIB 2016, 2016Konferensbidrag, Publicerat paper (Refereegranskat)
Nationell ämneskategori
Tribologi (ytteknik omfattande friktion, nötning och smörjning)
Forskningsämne
Maskinelement
Identifikatorer
urn:nbn:se:ltu:diva-41891 (URN)
Konferens
17th Nordic Symposium on Tribology - NORDTRIB 2016, Aulanko, Hämeenlinna, Finland, 14–17 June 2016
Tillgänglig från: 2016-10-04 Skapad: 2016-10-04 Senast uppdaterad: 2018-02-05
Berglund, K., Marklund, P., Lundh, H. & Larsson, R. (2016). Prediction of driveline vibrations caused by ageing the limited slip coupling (ed.). Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering, 230(12), 1687-1698
Öppna denna publikation i ny flik eller fönster >>Prediction of driveline vibrations caused by ageing the limited slip coupling
2016 (Engelska)Ingår i: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering, ISSN 0954-4070, E-ISSN 2041-2991, Vol. 230, nr 12, s. 1687-1698Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The prediction of the wet-clutch service life still remains a challenge for scientists and engineers. Previous research has shown the significance of the wet-clutch friction characteristics on the driveline dynamics. To avoid driveline vibrations an increasing friction coefficient with increasing sliding speed is desirable. Consequently, prediction of the occurrence of driveline vibrations relies on a detailed knowledge of how the friction characteristics are affected by wet-clutch degradation, as well as an understanding of the driveline dynamics. Wet clutches are used in both automatic transmissions and all-wheel-drive systems in cars, where they are referred to as limited slip couplings by manufacturers. Wet clutches used in automatic transmissions are subjected to high slip levels, but for very limited time periods. In all-wheel-drive systems, where the limited slip coupling can be used to control the torque transfer to, for example, the rear wheels, the slip levels are low but continuous. Most wet-clutch research has been performed for clutches in automatic transmissions and not for clutches used in all-wheel-drive systems. Thus, a simulation model was developed to evaluate how different operating conditions of the limited slip coupling influence degradation of the friction characteristics and the tendencies towards driveline vibrations. First, the changes in the friction characteristics with the time of ageing are simulated. The friction characteristics after ageing are used as the input to a simplified driveline model, which is used to evaluate the occurrence of vibrations. It is shown how the developed simulation model can be used as an efficient tool for engineers. The developed simulation model can be used to predict how the operating conditions for the limited slip coupling influence degradation of the friction characteristics.

Nationell ämneskategori
Tribologi (ytteknik omfattande friktion, nötning och smörjning)
Forskningsämne
Maskinelement
Identifikatorer
urn:nbn:se:ltu:diva-4024 (URN)10.1177/0954407015619505 (DOI)000383949700006 ()2-s2.0-84988328397 (Scopus ID)1e0ebf18-27ea-4e0e-8161-974736d58461 (Lokalt ID)1e0ebf18-27ea-4e0e-8161-974736d58461 (Arkivnummer)1e0ebf18-27ea-4e0e-8161-974736d58461 (OAI)
Anmärkning

Validerad; 2016; Nivå 2; 2016-10-14 (andbra)

Tillgänglig från: 2016-09-29 Skapad: 2016-09-29 Senast uppdaterad: 2018-07-10Bibliografiskt granskad
Shi, Y., Vadivel, H. & Berglund, K. (2016). Studying the tribological properties of PEEK composites lubricated by different lubricants for hydropower turbine application. In: Nordic Symposium on Tribology - NORDTRIB 2016: . Paper presented at 17th Nordic Symposium on Tribology - NORDTRIB 2016, Aulanko, Hämeenlinna, Finland, 14–17 June 2016.
Öppna denna publikation i ny flik eller fönster >>Studying the tribological properties of PEEK composites lubricated by different lubricants for hydropower turbine application
2016 (Engelska)Ingår i: Nordic Symposium on Tribology - NORDTRIB 2016, 2016Konferensbidrag, Publicerat paper (Refereegranskat)
Nationell ämneskategori
Tribologi (ytteknik omfattande friktion, nötning och smörjning)
Forskningsämne
Maskinelement
Identifikatorer
urn:nbn:se:ltu:diva-41892 (URN)
Konferens
17th Nordic Symposium on Tribology - NORDTRIB 2016, Aulanko, Hämeenlinna, Finland, 14–17 June 2016
Tillgänglig från: 2016-10-04 Skapad: 2016-10-04 Senast uppdaterad: 2018-02-05
Organisationer
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0002-8533-897x

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