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Systems : open access journal 9(4), 76-97 (2021). doi:10.3390/systems9040076, Published by MDPI, Basel

Applied Sciences 11(16), 7246 (2021). doi:10.3390/app11167246, Published by MDPI, Basel

This work is focused on demonstrating the possibilities of using X-ray Computerized Tomography laboratory equipment based on density measurements for making 3D maps of White Etching Crack networks in bearings. Four bearing specimens have been investigated that contained different crack morphologies which were visualized in 3D. For crack reconstruction, simple global and local threshold procedures have been successfully applied, although there are certain limitations for narrow cracks or crack tips. Specific features on the crack networks could be identified, such as crack interaction with inclusions, which was verified using microscopy characterization. By using the 3D maps as a guide for sectioning, these features were subsequently investigated with scanning electron microscopy (SEM) and chemical analysis. Through stress calculations it was demonstrated that the depth of the maximum Tresca stress and the location of WEC correlate when the real load and stress history is known. The propagation direction of the WEC is however not defined by critical plane orientation.

The present study aims to predict the wear in journal bearings during steady-state operation in the mixed-lubrication regime starting with a critical assessment of commonly used wear laws. A novel numerical method is introduced that calculates journal bearing wear on macroscopic and asperity contact scale. For validation of the numerical method, the friction and wear behavior was studied on a special test-rig for journal bearings. Both experimental and numerical results show an initial period of high friction and wear. After the first minutes of operation reduced friction can be observed. The simulations clarify, that this is caused by bearing wear on asperity roughness scale. By considering the reduced asperity interaction due to wearing-in in the calculation of contact conditions a higher accuracy of wear prediction is achieved.

Condition monitoring and fault diagnosis are methods to achieve a higher reliability for complex mechanical systems. Due to the ability of acoustic emission (AE) technology to detect damages during at an early stage, AE has high potential to be considered in novel machine condition monitoring systems. Since AE waves are generated due to rapid releases of strain energy, such as crack propagation, roughness contact and mechanical impacts, it is possible to use multiple AE sensors to track down the AE source location. This paper presents an accurate and easy-to-use methodology to locate AE sources in ring gears from planetary gearboxes. The methodology uses AE wave’s time of arrival calculated from three signal differential envelopes. The time of arrival is subsequently used to analytically determine the angular position of the AE source. The proposed methodology was tested in two different real-sized wind turbine gearboxes using Hsu-Nielsen sources. The results showed that, with the correct selection of filter cut-off frequencies, the localization could be carried out with an error equivalent to only two teeth from the correct position, indicating the good performance of the approach.

The formation of tribological surface layers is essential for ultra-mild wear. These surface layers form during machine operation in lubricated conditions with additives. Zinc-dialkyldithiophosphates (ZDDP) are frequently used anti-wear additives, but their future use is limited due to environmental concerns. The design of next-generation additives requires a thorough understanding of the tribolayer formation mechanisms of current additives. The present work describes novel macro- and microscale experiments at room temperature that have a limited number of parameters and that use cyclic contact to form tribological surface layers. The new setup allows focusing on the influence of the mechanical stresses, which are very localized in this setup. This study shows that compression creates surface layers even with limited shear driven lubricant flow.

The present study experimentally examines the effect of selected single-scale and multi-scale surface patterns fabricated by roller-coining and/or direct laser interference patterning on the frictional performance of journal bearings. For this purpose, surface patterns showing beneficial effects in preliminary laboratory tests were selected and fabricated onto the shaft of journal bearings made of stainless steel (AISI 304). The frictional performance of these patterns was evaluated on a special test rig by recording Stribeck-like curves. The results show greatly reduced coefficients of friction and a shift in the transition from mixed to hydrodynamic lubrication to smaller rotational speeds for all patterned samples compared to the reference sample. The observed friction reduction matches well with results observed in the previous laboratory tests.

Hydrogen-fired gas turbines have the potential to play an important role in decarbonized energy sectors. However, a demand-oriented supply of CO2-neutral hydrogen for the operation of gas turbines is technically and economically challenging. These challenges mainly arise due to various interdependencies between the volatility of renewable power generation, available hydrogen production capacities, available hydrogen storage capacities and the operational demands to be met by gas turbines. The present study aims to quantify these interdependencies by conducting a detailed model-based analysis of an exemplary combined heat and power system featuring a hydrogen-fired industrial gas turbine with on-site hydrogen production via electrolysis and on-site hydrogen storage in pressure vessels. In order to identify the sought-after interdependencies, simulation runs featuring various combinations of available hydrogen production and storage capacities are analyzed. If only local power surpluses are utilized for the electrolysis, the obtained results reveal a strong non-linear impact of both the hydrogen production capacity and the storage capacity on the ability to provide hydrogen for the gas turbine. Furthermore, the results indicate that an exclusive utilization of local power surpluses leads to very limited periods of hydrogen-based gas turbine operation and low utilization rates of the available hydrogen production and storage capacities. If additional power for the operation of electrolyzers is supplied by the grid, increased utilization rates and prolonged periods of hydrogen-based gas turbine operation can be achieved. However, in order to realize an overall reduction of CO2 emissions, this mode of operation requires the supply of large quantities of renewable power by the grid. Furthermore, the results of an additional economic analysis reveal that both investigated operational modes are currently not economically viable within the considered economic framework.

Lubricants : open access journal 9(8), 80 (2021). doi:10.3390/lubricants9080080 special issue: "Special Issue "Grease" / Special Issue Editors: Dr. Raj Shah, Guest Editor ; Dr. Mathias Woydt, Guest Editor ; Dr. Simon C. Tung, Guest Editor ; Prof. Dr. Andreas Rosenkranz, Guest Editor", Published by MDPI, Basel

Forschung im Ingenieurwesen (2021). doi:10.1007/s10010-021-00460-3, Published by Springer, Berlin ; Heidelberg

Dieses Kapitel zeigt das Potenzial der Datennutzung in der Landwirtschaft und in der Baubranche auf. Neben heutigen Wertschopfungsmechanismen wie beispielweise der datengestutzten Prozessoptimierung und der pradiktiven Instandhaltung werden kunftige Wertschopfungsmoglichkeiten wie beispielweise die Erschliesung neuer Geschaftsmodelle und Dienstleistungen vorgestellt. Um zunachst die heutige Nutzung generierter Daten zu beschreiben, werden die Monetarisierungsmechanismen aktueller datengetriebener Produkte und Losungen beider Branchen analysiert. Anschliesend werden die bestehenden Hemmnisse der Datennutzung und -verauserung identifiziert. Um die identifizierten Hemmnisse aufzulosen, werden Losungsansatze definiert und in einem Leitfaden zusammengefasst, welcher die Erschliesung neuer datengetriebener Geschaftsmodelle fokussiert. Zur Demonstration der Wirkweise des entwickelten Leitfadens wird dieser in konkreten Fallbeispielen aufgegriffen, in denen die Ausarbeitung kunftiger datengetriebener Geschaftsmodelle in der Landwirtschaft und in der Baubranche konkretisiert wird.

19th Drive Train Technology Conference (ATK 2021) 9th-11th March 2021, Aachen, Germany 19. Antriebstechnisches Kolloquium = 19th Drive Train Technology Conference, ATK 2021, online, 9 Mar 2021 - 11 Mar 2021; London [u.a.] : Institute of Physics, IOP Conference Series: Materials Science and Engineering 1097, 012013, 1-12 (2021). doi:10.1088/1757-899X/1097/1/012013, Published by Institute of Physics, London [u.a.]

Tribology letters 69(4), 136 (2021). doi:10.1007/s11249-021-01508-9, Published by Springer Science Business Media B.V., Dordrecht

19th Drive Train Technology Conference (ATK 2021) : 9th-11th March 2021, Aachen, Germany / editorial board: Prof. Dr.-Ing. Georg Jacobs, Sebastian Stein, M.Sc. 19. Antriebstechnisches Kolloquium = 19th Drive Train Technology Conference, ATK 2021, online, 9 Mar 2021 - 11 Mar 2021; [Bristol] : IOP Publishing, IOP conference series. Materials science and engineering 1097, 012007, 1-13 (2021). doi:10.1088/1757-899X/1097/1/012007, Published by IOP Publishing, [Bristol]

Forschung im Ingenieurwesen (2021). doi:10.1007/s10010-021-00462-1, Published by Springer, Berlin ; Heidelberg

Forschung im Ingenieurwesen = Engineering research (2021). doi:10.1007/s10010-021-00481-y, Published by Springer, Berlin ; Heidelberg

19th Drive Train Technology Conference (ATK 2021) 9th-11th March 2021, Aachen, Germany 19. Antriebstechnisches Kolloquium, ATK 2021, online, 9 Mar 2021 - 11 Mar 2021; London [u.a.] : Institute of Physics 012012, 1-10 (2021). doi:10.1088/1757-899X/1097/1/012012, Published by Institute of Physics, London [u.a.]

Wind energy science discussions : WESD 6(1), 177-190 (2021). doi:10.5194/wes-6-177-2021, Published by Copernicus Publications, Göttingen

Forschung im Ingenieurwesen (2021). doi:10.1007/s10010-021-00471-0, Published by Springer, Berlin ; Heidelberg

Forschung im Ingenieurwesen : research journal = Engineering research (2021). doi:10.1007/s10010-021-00461-2, Published by Springer, Berlin ; Heidelberg

Forschung im Ingenieurwesen = Engineering research (2021). doi:10.1007/s10010-021-00456-z, Published by Springer, Berlin ; Heidelberg

Friction (2020). doi:10.1007/s40544-020-0417-9, Published by Springer, Berlin

Forschung im Ingenieurwesen = Engineering research (2021). doi:10.1007/s10010-021-00443-4, Published by Springer, Berlin

19th Drive Train Technology Conference (ATK 2021) 9th-11th March 2021, Aachen, Germany 19. Antriebstechnisches Kolloquium = 19th Drive Train Technology Conference, ATK 2021, online, 9 Mar 2021 - 11 Mar 2021; London [u.a.] : Institute of Physics 012002, 1-15 (2021). doi:10.1088/1757-899X/1097/1/012002, Published by Institute of Physics, London [u.a.]

Materials 14(17), 5004 (2021). doi:10.3390/ma14175004 special issue: "Special Issue "Laser Processing for Composite Materials" / Special Issue Editor: Prof. Dr. Irina Hussainova, Guest Editor", Published by MDPI, Basel

Forschung im Ingenieurwesen (2021). doi:10.1007/s10010-021-00472-z, Published by Springer, Berlin ; Heidelberg

Wind energy science : WES 6(2), 571-584 (2021). doi:10.5194/wes-6-571-2021, Published by Copernicus Publications, Göttingen

Doubly fed induction generators are widely used in wind turbines in the field. The main advantage is the significantly lower cost of the partial scale power converter compared to the full scale power converter. Converter faults in wind turbines lead to significant generator torque excitations that lead to dynamic loads in the drivetrain. Dynamic loads and changing rotational speeds can lead to gearbox damages. The generator torque excitations have the highest influence on the high speed shaft torque due to the coupling to the generator. Gearbox damages occur mainly on the components of the high speed shaft. Thus, in this paper the influence of a converter fault in a wind turbine with doubly fed induction generator on the high speed shaft component damages is investigated. It is shown that the converter fault can induce dynamic torque excitations with a maximum increase to around 2.5 times rated torque. Due to the resulting dynamic gearbox loading the safety against scuffing in the high speed gear stage decreases by maximum 19 percent. The smearing risk in the high speed shaft bearings increases to around 2 times the value during rated power production.

Innovations in Cyber-Physical System (CPS) are driven by functionalities and features. Mechanical Engineering, on the other hand, is mainly concerned with the physical product architecture, i.e., the hierarchical arrangement of physical components and assemblies that forms the product, which is not explicitly linked to these functions. A holistic model-driven engineering approach for CPS, therefore, needs to bridge the gap between functions and the physical product architecture to enable agile development driven by automation. In the theoretical field of mechanical design methodology, functional architectures describe the functionality of the system under development as a hierarchical structure. However, in practice, these are typically not considered let alone modeled. Existing approaches utilizing mechanical functional architectures, however, do not formalize the relation between the functional architecture and the geometric design. Therefore, we conceived a meta-model that defines modeling-languages for modeling functional architectures of mechanical systems and physical solutions, i.e., interconnections of physical effects and geometries, as refinements of the functional components. We have encoded the meta-model as a SysML profile and applied it within an interdisciplinary, industrial project to model an automotive coolant pump. Our contribution signposts the potential of functional structures to not only bridge the gap between function and geometry in mechanics but also to integrate the heterogeneous domains participating in CPS engineering.

Wind farm sites within complex terrain are subject to local wind phenomena, which have a huge impact on a wind turbine's annual energy production. To reduce investment risk, an extensive site evaluation is therefore mandatory. Stationary long-term measurements are supplemented by CFD simulations, which are a commonly used tool to analyse and understand the three-dimensional wind flows above complex terrain. Though being under heavy research, such simulations still show a huge sensitivity for various input parameters like terrain, atmosphere and numerical setup. Within this paper, a different approach aims to measure instead of simulate wind speed deviations above complex terrain by using a flexible, airborne measurement system. An unmanned aerial vehicle is equipped with a standard ultrasonic anemometer. The uncertainty of the system is evaluated against stationary anemometer at different heights and shows very good agreement, especially in mean wind speed (

Wind energy science discussions : WESD 6(2), 367-376 (2021). doi:10.5194/wes-6-367-2021, Published by Copernicus Publications, Göttingen

The Science of Making Torque from Wind, TORQUE 2020, , 28 Sep 2020 - 2 Oct 2020; Journal of physics / Conference series 1618: The Science of Making Torque from Wind (TORQUE 2020) 28 September – 2 October 2020, The Netherlands (online)(5) 052025 (2020). doi:10.1088/1742-6596/1618/5/052025 special issue: "Turbine Technology", Published by IOP Publ., Bristol

Applied Sciences 10(20), 7086 (2020). doi:10.3390/app10207086, Published by MDPI, Basel

Availability of offshore systems significantly affects operational costs and is therefore an important performance indicator. In order to ensure a high system availability, failures of equipment must be avoided. Condition monitoring for detection of upcoming failures usually requires an elaborate and therefore costly sensor infrastructure. This paper presents a method that aims to acquire condition information of gearbox components of ship-mounted offshore crane winches by using only already available and easily accessible external load information, such as motor torque, wave height and carried payload. For offshore cranes equipped with Active Heave Compensation (AHC) technology, the drivetrain loads depend significantly on the wave-induced motion of the ship and subsequently of the crane. The resulting motion of the load-determining crane tip is calculated using wave height predictions and the dynamic behaviour of the ship. With an appropriate system model, the local component loads can be calculated in a way that each component’s remaining lifetime can be estimated by applying component lifetime models. Furthermore, critical components can be identified and monitored to avoid unplanned downtime of the equipment.

The Science of Making Torque from Wind, TORQUE 2020, , 28 Sep 2020 - 2 Oct 2020; Journal of physics / Conference series 1618: The Science of Making Torque from Wind (TORQUE 2020) 28 September – 2 October 2020, The Netherlands (online)(5) 052037 (2020). doi:10.1088/1742-6596/1618/5/052037 special issue: "Turbine Technology", Published by IOP Publ., Bristol

Friction (2020). doi:10.1007/s40544-020-0454-4, Published by Springer, Heidelberg

Science of Making Torque from Wind 2020, TORQUE 2020, online, print, 28 Sep 2020 - 2 Oct 2020; Journal of physics / Conference series 1618(5), 052004 (2020). doi:10.1088/1742-6596/1618/5/052004 special issue: "The Science of Making Torque from Wind (TORQUE 2020) 28 September – 2 October 2020, The Netherlands", Published by IOP Publ., Bristol

Journal of physics / Conference series Conference series 1452, 012062 (2020). doi:10.1088/1742-6596/1452/1/012062, Published by IOP Publ., Bristol

International Design Conference, DESIGN 2020, Cavtat, Croatia, 26 Oct 2020 - 29 Oct 2020; Proceedings of the Design Society / DESIGN conference 1, 2435-2444 (2020). doi:10.1017/dsd.2020.287 special issue: "[International Design Conference, DESIGN 2020]", Published by Cambridge University Press, Cambridge

TORQUE 2020, online, 28 Sep 2020 - 2 Oct 2020; Journal of physics / Conference series 1618, 052056 (2020). doi:10.1088/1742-6596/1618/5/052056 special issue: "The Science of Making Torque from Wind (TORQUE 2020)", Published by IOP Publ., Bristol