Abrasivity is a characteristic property of rocks. Rock abrasivity has influence on tool wear, energy consumption and construction time and is therefore an important parameter in rock engineering. Over the years, a number of testing methods have been developed to define and quantify the abrasive potential of rocks. Due to simple design and convenient handling, Cerchar abrasivity test and its index, Cerchar abrasivity index, are most commonly used to assess the rock abrasivity. Besides the abrasivity index, various parameters can be derived from the Cerchar test thanks to the development of a special designed testing device. Diverse parameters like scratching force, applied work and specific energy can be used to estimate the cutting efficiency. Moreover, a new composite parameter named Cerchar abrasion ratio is proposed, which considers both, the wear on the stylus tip and the material removal on the rock surface and can be regarded as an indicator to evaluate the cutting effectivity. Since the development of Cerchar abrasivity test, major attentions are focused on the abrasion of the stylus, but minor attentions are paid to investigate the mechanical behavior of rocks against the action of the stylus during the scratching process. The scratch groove produced on the rock surface is observed under a scanning electron microscope. The Cerchar wear mechanism can be explained as follows: mineral grains are detached from damaged surface by fracturing after plastic deformation on stressed surface. Transition from plastic deformation-induced to cracking-induced wear are related to the rock microstructure. For the Cerchar test, various factors affecting the Cerchar abrasivity index have been studied, which can be divided into testing condition-based and geotechnical-based factors. The influence of some dominant testing condition-based factors including surface condition, testing distance and velocity on the test result is investigated by using the new designed testing device, in which the sliding distance and scratching velocity can be exactly controlled during the test. Results show that the surface condition can affect the result of Cerchar index, especially for hard and inhomogeneous rocks, while the testing distance and velocity have no obvious influence on the Cerchar index. As far as it is known, in rock mechanics, anisotropic features of rocks can affect the experimental results significantly. In the original Cerchar specification, testing procedure for stratified or foliated rocks is not specially discussed. Due to this, the influence of rock anisotropy on the Cerchar abrasivity index is investigated based on two intact metamorphic rocks of slate and gneiss. However, no significant dependency is found. Cerchar scratch test is simulated based on a quasi-homogeneous model made of sandstone with respect to its mineralogical-mechanical properties. The numerical simulation is conducted by using the discrete element method-based particle flow code of PFC3D. As a result, the simulated scratching force shows a good agreement with the experimental result. A gap between numerical and experimental studies can be attributed to the testing condition-based factors, such as rock mineralogy and microstructure, scratching velocity and depth of scratch, tool abrasion and temperature. Based on the calibrated sandstone model, numerical simulations of rock cutting are conducted under different testing conditions. The influence of tool geometry like tip shape, tip angle and tip wear, and cutting parameters including cutting velocity, depth of cut and rake angle on the cutting force and crack pattern is studied.

Axial piston pumps are universal displacement machines that are used in a vast variety of applications. Their high pressure resistance and ease of operation make them very popular, especially in mobile applications. Some applications require more robust pumps with an extended lifetime, particularly those that operate in remote environments such as marine type or mining operations. Especially new applications like displacement control have high demands on pumps such as through shaft operation (many pumps on one shaft), high dynamics and multi-quadrant operation. These demands create challenges in terms of lifetime expectancy and robustness for pump manufacturers and machine OEMs. Currently most axial piston pumps go through a run-in process. During this process the softer bronze parts shave off and change their shape according to the necessary one for the pumps’ proper operation. This process is highly dependent on the design of the parts and their manufacturing tolerances. In this paper the run-in process of the slippers of an axial piston pump was investigated by means of measurements of the gap height and wear profile as well as simulation. The measurements show a clear change of profile and gap heights for the first 120 h of the pumps operation. After that the gaps stabilize. The numerical simulations made with the program Caspar FSTI were coupled with contact wear models to output wear profiles. Different models will be introduced and compared with measurements. Both the amount of material removed and the performance of the pump before and after run-in will be discussed.

With increasing digitization, models are more important than ever. Especially their use as soft sensors during operation offers opportunities in cost saving, easy data acquisition and therefore additional functionality of systems. In soft sensor networks there is redundant data acquisition and consequently the occurrence of inconsistent values from different soft sensors is encouraged. The resolution of these data-induced conflicts allows for the detection of changing components characteristics. Hence soft sensor networks can be used to detect wear in system components. In this paper this approach is validated on a test rig. It is found, that the soft sensor network is capable to determine wear and its extent in eccentric screw pumps and valves via data induced conflicts with relatively simple models.

The novel alloying concept of high-entropy alloys (HEAs) has been the focus of many recent investigations revealing an interesting combination of properties. Alloying with aluminium and titanium showed strong influence on microstructure and phase composition. However, detailed investigations on the influence of titanium are lacking. In this study, the influence of titanium in the alloy system AlCoCrFeNiTix was studied in a wide range (molar ratios x = 0.0; 0.2; 0.5; 0.8; 1.0; 1.5). Detailed studies investigating the microstructure, chemical composition, phase composition, solidification behaviour, and wear behaviour were carried out. Alloying with titanium showed strong influence on the resulting microstructure and lead to an increase of microstructural heterogeneity. Phase analyses revealed the formation of one body-centred cubic (bcc) phase for the alloy without titanium, whereas alloying with titanium caused the formation of two different bcc phases as main phases. Additional phases were detected for alloys with increased titanium content. For x ≥ 0.5, a minor phase with face-centred cubic (fcc) structure was formed. Further addition of titanium led to the formation of complex phases. Investigation of wear behaviour revealed a superior wear resistance of the alloy AlCoCrFeNiTi0.5 as compared to a bearing steel sample.

An Oberleitungen von spurgeführten elektrischen Nahverkehrssystemen werden sehr hohe Zuverlässigkeitsanforderungen gestellt, die durch eine belastungsgerechte Instandhaltung erfüllt werden. Die gegenwärtige Instandhaltungspraxis wird analysiert und die damit erreichte Anlagenverfügbarkeit bestimmt. Als Ergebnis dieser Analyse werden die Arbeitsschwerpunkte identifiziert und besonders instandhaltungsintensive Komponenten oder Bauweisen der Oberleitung ermittelt. An diesen wird untersucht, woraus der erhöhte Instandhaltungsaufwand resultiert und mit welchen Abhilfemaßnahmen dem entgegen gewirkt werden kann. Dabei wird ein Bündel von Einzelmaßnahmen durch theoretische Betrachtungen, Labor- und Feldversuche sowie Simulationsrechnungen betrachtet und die Wirksamkeit bewertet. Parallel wird ein fahrzeugseitiges Monitoringsystem zur qualitativen Bewertung der Kontaktgüte zwischen Stromabnehmer und Oberleitung entwickelt, erprobt und verifiziert. Zusammen mit dafür entwickelten Auswertungsfunktionen können automatisiert instandhaltungsintensive Punkte im gesamten Netz detektiert und charakterisiert werden. Zusammen mit statistisch ausgewerteten Felddaten können verschleißbestimmende Parameter errechnet werden, die den Anlageninstandhalter bei der Zustandsbestimmung seines Netzes unterstützen. Dem Anlagenbetreiber wird ermöglicht, die Instandhaltung zielgerichtet auf verschleißintensive Komponenten zu fokussieren und mit zuvor untersuchten Abhilfemaßnahmen den Instandhaltungsbedarf zu senken.

Die Arbeit widmet sich der Einsatzplanung von Luftfahrzeugen (LFZ) und fokussiert dabei auf die herausfordernde Thematik des Verschleißes, der zu einer Heterogenität in der Brennstoffeffizienz innerhalb der Flotte führt. Dieser heterogene Effekt wird durch den sogenannten 'Performance Factor' (PF) quantifiziert, der den Verbrauch im Vergleich zu einem nicht verschleißbehafteten Referenz-LFZ adjustiert. Trotz der nachgewiesenen Auswirkungen auf die Effizienz wird der PF bisher in der Einsatzplanung weitgehend vernachlässigt. Das Ziel dieser Forschungsarbeit besteht in der systematischen Untersuchung des Potenzials zur Reduzierung des Brennstoffbedarfs und der damit verbundenen CO2-Emissionen durch eine effizienzorientierte Einsatzplanung mittels Berücksichtigung des PF. Zu diesem Zweck wird ein taktisches Modell, das sogenannte 'TARP-Modell,' entwickelt. Es ermöglicht eine integrierte Lösung der Phasen des Aircraft Routings und des Tail Assignments, wodurch individuelle Flugdurchführungskosten unter Berücksichtigung der Heterogenität der Flüge und der PF-Verteilung in der Flotte ermittelt werden können. Die erzielten Ergebnisse verdeutlichen, dass eine effizienzorientierte Einsatzplanung eine Senkung der Brennstoffkosten um etwa 0,25% bis 0,5% ermöglicht. Selbst bei unvorhergesehenen Flugplanstörungen und der vermehrten Nutzung von sogenannten Aircraft Swaps (TARP-R-Modell) bleibt das Potenzial weitestgehend erhalten, sofern der PF angemessen in die Entscheidungsfindung integriert wird. Es ist jedoch zu beachten, dass das Potenzial mit zunehmender Komplexität in der Flug- und LFZ-Zuordnung durch verstärkte Restriktionen abnehmen kann. Die vorliegende Arbeit leistet somit einen Beitrag zur Ressourcenschonung und zur Verringerung der Klimawirksamkeit des Luftverkehrs. Es ist anzunehmen, dass zukünftige technologische Fortschritte im Bereich des digitalen Zwillings die Berechnung des PF noch präziser gestalten werden, wodurch dessen Bedeutung sowohl wissenschaftlich als auch operationell weiter an Bedeutung gewinnen dürfte. / The thesis is dedicated to the aircraft rotation and assignment and focuses on the challenging issue of aircraft performance degradation, which leads to heterogeneity in fuel efficiency within the fleet. This heterogeneous effect is quantified by the so-called 'Performance Factor' (PF), which adjusts fuel consumption in comparison to a non-worn reference aircraft. Despite its proven impact on efficiency, the PF has largely been disregarded in aircraft planning practices. The main objective of this research is to systematically investigate the potential for reducing fuel consumption and associated CO2 emissions through an efficiency-oriented aircraft planning approach, incorporating consideration of the PF. To achieve this goal, a tactical model, referred to as the 'TARP model,' is developed. The model facilitates an integrated solution to the aircraft routing and tail assignment phases, enabling the determination of individual flight execution costs while accounting for the heterogeneity of flights and PF distribution in the fleet. The results obtained underscore that an efficiency-oriented aircraft planning approach can yield a reduction in fuel costs of approximately 0.25% to 0.5%. Even in the presence of unforeseen flight schedule disruptions and increased utilization of aircraft swaps (TARP-R model), the potential remains largely preserved, provided the PF is adequately integrated into the decision-making process. Nevertheless, it should be noted that the potential may diminish with growing complexity in flight and aircraft assignment, stemming from heightened restrictions. Consequently, this study contributes to resource conservation and the mitigation of the aviation industry's climate impact. Anticipated advancements in digital twin technologies are expected to further refine PF calculations, enhancing its significance both from a scientific and operational standpoint.

In der vorliegenden Arbeit wird der abrasive Verschleiß von Textilsilos näher betrachtet. Ziel der Untersuchungen ist die Auslegung eines geeigneten Prüfstands, um die Eignung verschiedener textiler Flächenelemente für den Einsatz als Silowandung zu prüfen. Es werden zunächst die unterschiedlichen etablierten physikalischen Verschleiß-Prüfungen vorgestellt und an Hand der Stand der Technik eine eigene Prüfvorrichtung entwickelt. Anschließend werden die charakteristischen Kennwerte der ausgewählten Schüttgüter und textilen Proben ermittelt. Verschiedene Schüttgut-Textil Kombinationen werden in der neuen Prüfvorrichtung getestet und anhand verschiedener Auswertemethoden die damit ermittelten Messwerte auf Plausibilität geprüft.:1 Einleitung und Zielstellung 2 Wissenschaftlich-technische Grundlagen der Schüttgutlagerung in Silos 3 Präzisierung der Aufgabenstellung 4 Siloauslegung in Anlehnung an DIN EN 1991-4 5 Experimentelle Untersuchungen 6 Versuchsdurchführung und Auswertung 7 Zusammenfassung und Ausblick / In the present work, the abrasive wear of textile silos is examined in more detail. The aim of the investigations is the design of a suitable test bench to test the suitability of various textile surface elements for use as silo walls. First, the various established physical wear tests are presented and a separate test device is developed on the basis of the state of the art. Subsequently, the characteristic values of the selected bulk materials and textile samples are determined. Various bulk material-textile combinations are tested in the new test device. The measured values determined with it are checked for plausibility using various evaluation methods.:1 Einleitung und Zielstellung 2 Wissenschaftlich-technische Grundlagen der Schüttgutlagerung in Silos 3 Präzisierung der Aufgabenstellung 4 Siloauslegung in Anlehnung an DIN EN 1991-4 5 Experimentelle Untersuchungen 6 Versuchsdurchführung und Auswertung 7 Zusammenfassung und Ausblick

Wear on total knee replacements is an important criterion for their performance characteristics. Numerical simulations of such wear have seen increasing attention over the last years. They have the potential to be much faster and less expensive than the in vitro tests in use today. While it is unlikely that in silico tests will replace actual physical tests in the foreseeable future, a judicious combination of both approaches can help making both implant design and pre-clinical testing quicker and more cost-effective. The challenge today for the design of simulation methods is to obtain results that convey quantitative information and to do so quickly and reliably. This involves the choice of mathematical models as well as the numerical tools used to solve them. The correctness of the choice can only be validated by comparing with experimental results. In this article, we present finite element simulations of the wear in total knee replacements during the gait cycle standardized in the ISO 14243-1 document, used for compliance testing in several countries. As the ISO 14243-1 standard is precisely defined and publicly available, it can serve as an excellent benchmark for comparison of wear simulation methods. We use comparatively simple wear and material models, but we solve them using a new wear algorithm that combines extrapolation of the geometry changes with a contact algorithm based on nonsmooth multigrid ideas. The contact algorithm works without Lagrange multipliers and penalty parameters, achieving unparalleled stability and efficiency. We compare our simulation results with the experimental data from physical tests using two different actual total knee replacements. Even though the model is simple, we can predict the total mass loss due to wear after 5-million gait cycles, and we observe a good match between the wear patterns seen in experiments and our simulation results. When compared with a state-of-the-art penalty-based solver for the same model, we measure a roughly fivefold increase of execution speed.

Synthetische Hochleistungswerkstoffe, in Faserform, haben sich bisher in Gebieten wie dem Freizeitsport (Klettersport, Segelsport), Seetechnik (Ankerleinen, Zugleinen) und Schutzausrüstung (Ballistik, Arbeitsschutzbekleidung) bewehrt. Die Einführung von Hochleistungsfasern in weiteren Anwendungsfeldern wird durch Schwachstellen im Materialverhalten der Fasern selbst verhindert. So gilt unter Anwendern und Entwicklern das Problemfeld des inneren Verschleißes der textilen Halbzeuge bei Belastung auf Zug und Biegung, durch gegenseitiges Schädigen der Garne, als Haupthindernis zur weiteren Verbreitung von Textilstrukturen aus synthetischen Hochleistungspolymeren. Es kann davon ausgegangen werden, dass die Lebensdauer von z.B. Seilen und Bändern aus Hochleistungsfasern signifikant erhöht werden kann, falls es gelingt, bestimmte Schädigungsmechanismen wie Alterung durch Strahlung, aggressive Medieneinflüsse und inneren Verschleiß auszuschließen bzw. zu mindern. Da eine, wie auch immer geartete, nachträgliche Ausrüstung oder Modifizierung der Hochleistungsfasern durch den Weiterverarbeiter (z.B. Seilerei, Weberei, Konfektionär etc.) oder individuelle Bereitstellungen durch die Hersteller ausgeschlossen ist, werden für die Erarbeitung von Lösungsansätzen folgende Randbedingungen vorgeschlagen: die Modifikation des Endverbundes erfolgt nicht durch Veränderungen an der Hochleistungsfaser, sondern durch zusätzlich eingebrachte Hilfsfasern. Das Einbringen der Hilfsfasern soll mit in der Textiltechnik üblicher Weise vorhandener Maschinentechnik möglich sein. Die Ausrüstung der Hilfsfasern erfolgt vorrangig durch Additive, primär mittels Compoundierung im Schmelzspinnprozess. Die vorliegende Arbeit wird zunächst versuchen die Auswirkungen dynamischer Belastungsprozesse auf textile Zug- und Tragmittel aus Hochleistungsfasern zu erfassen. Nach Aufnahme des Schadbildes werden dann die ausgerüsteten Hilfsfasern charakterisiert, d.h. es werden solche mechanischen und physikalischen Parameter erfasst und deren Änderung beschrieben, welche in dem zu erwartenden tribologischen System aus Hochleistungsfaser und Hilfsfasern ausschlaggebend sind. / Advanced synthetic materials, in the shape of synthetic high-performance fibers, are well established in areas such as leisure sports (climbing, sailing), maritime technology (anchor lines, load lines) and reinforced protective equipment (ballistics, protective work clothing). The introduction of high-performance fibers in other fields of application is hindered by deficiencies in the material behavior of the fibers themselves. Whereas the problem of inner wear of the textile-semi-finished products, due to tension and bending loads, causes mutual harm to the fibers. This is considered being the main obstacle to the further spread of textile structures made of synthetic high-performance polymers among users and developers. It can be assumed that a significantly increase of lifetime, of e.g. fiber ropes and narrow fabrics, can be achieved if it succeeds, to exclude certain damage mechanisms such as aging resulting from radiation, aggressive media influences and inner wear. Since any subsequently equipment or modification of high-performance fibers by the manipulators (e.g. rope factory) or individual deployments by the manufacturer are excluded, the following general conditions are suggested for the development of approaches in this work. The modification of the final textile product is not been carried out due to changes on the high-performance fiber, but by additionally introduced assisting fibers. Introducing the assisting fibers to the textile product needs to be carried out on textile technology in common ways on existing machinery. The modification of the assisting fibers will be carried out, primarily through commercially available additives, during compounding in the melt spinning process. This paper will first attempt to capture the effect of dynamic load processes on textile-based tension and hoist members, made of high-performance fibers. After recording the damage structure, the equipped assisting fibers are characterized then. The investigations are including such mechanical and physical parameters, which are crucial in the expected tribological system of high-performance fiber and assisting fibers.

High hardness and good wear resistance have been revealed for the high-entropy alloy (HEA) system AlCoCrFeNiTi, confirming the potential for surface protection applications. Detailed studies to investigate the microstructure and phase formation have been carried out using different production routes. Powder metallurgical technologies allow for much higher flexibility in the customisation of materials compared to casting processes. Particularly, spark plasma sintering (SPS) enables the fast processing of the feedstock, the suppression of grain coarsening and the production of samples with a low porosity. Furthermore, solid lubricants can be incorporated for the improvement of wear resistance and the reduction of the coefficient of friction (COF). This study focuses on the production of AlCoCrFeNiTi composites comprising solid lubricants. Bulk materials with a MoS2 content of up to 15 wt % were produced. The wear resistance and COF were investigated in detail under sliding wear conditions in ball-on-disk tests at room temperature and elevated temperature. At least 10 wt % of MoS2 was required to improve the wear behaviour in both test conditions. Furthermore, the effects of the production route and the content of solid lubricant on microstructure formation and phase composition were investigated. Two major body-centred cubic (bcc) phases were detected in accordance with the feedstock. The formation of additional phases indicated the decomposition of MoS2.