Entwicklung eines neuartigen Gleitlagers mit Faserverbundstruktur und Hochleistungskunststoffen — Auslegung, Modellierung & Prozessentwicklung

Aufgrund des geringen Eigengewichts, der herausragenden Trockenlaufeigenschaften und hohen Zuverlässigkeit sind Kunststoffgleitlager bereits heute in diversen Hochleistungsanwendungen ein essentieller Bestandteil. Nach dem Stand der Technik werden Kunststoffgleitbuchsen jedoch meist in ihre umgebende Struktur eingepresst, wobei es aufgrund des Kriechverhaltens zeitlich zu einer Verminderung der Fugenpressung kommt. Ein dauerhafter Einsatz der Lager bei erhöhten Temperaturen kann so zu einem Versagen führen. Hochleistungskunststoffcompounds kombiniert mit faserverstärkten Kunststoffen mit duroplastischer Matrix können hier die Leistungsgrenzen verschieben, wurden derzeit jedoch nicht systematisch beschrieben oder entwickelt. Das volle Potenzial der Werkstoffe ausreizend, liegt das Ziel der Arbeit in der Entwicklung eines derartigen Faserverbundgleitlagers mit einer Gleitschicht aus Hochleistungskunststoffen, einer faserverstärkten Stützschale auf duroplastischer Basis und einer Anbindung mittels SIPNs. Im Rahmen der Arbeit erfolgt die Auslegung und Modellierung eines solchen Gleitlagers und die Prozessentwicklung zur Herstellung dieser. Abgestimmt auf das Herstellungsverfahren wird ein Simulationsmodell entwickelt, mit welchem die mechanischen Eigenschaften neu entwickelter Compounds mit anisotropen Additiven ohne Werkstoffprüfung berechnet werden können. Basierend auf mechanischen Untersuchungen und auf Lösungsversuchen wird das Potenzial der Anbindung gezeigt. Wichtige Einflussgrößen werden identifiziert und relevante Prozessparameter und -grenzen für die Gleitlagerherstellung werden ebenfalls ermittelt. Rückgekoppelt mit den berechneten mechanischen Eigenschaften der Gleitschichtcompounds erfolgt eine Optimierung des Lagenaufbaus der Stützschale. Hierbei wird anhand der auftretenden Lagerkräfte der Lagenaufbau berechnet und die Auslegung des Gesamtsystems gesamthaft vorgenommen. Alle gewonnenen Erkenntnisse werden in der Prozessentwicklung zusammengeführt, woraus ein Herstellungsverfahren für die Gleitlager abgeleitet wird. Anschließend werden zur Validierung des Konzepts Lager gefertigt und erprobt. Somit zeigt diese Arbeit schlussendlich eine gesamthafte Auslegung samt zugehörigem Herstellungsverfahren des neuartigen Gleitlagers.Due to their low intrinsic weight, outstanding dry-running properties and high reliability, plastic plain bearings are already an essential component in various high-performance applications. However, according to the state of the art, plastic plain bearings are usually pressed into their surrounding structure, whereby a reduction in joint pressure occurs over time due to the creep behaviour. Usage of the bearings at elevated temperatures can thus lead to failure. High-performance plastic compounds combined with fibre-reinforced plastics with a thermosetting matrix can push the performance limits here, but have not been systematically described or developed yet. Exploiting the full potential of the materials, the aim of the work is to develop such a fibre composite bearing with a sliding layer of high-performance plastics, a fibre-reinforced support shell on a thermoset basis and a connection by means of SIPNs. Within the scope of the work, the design and modelling of such a plain bearing and the process development for its manufacture are carried out. Matched to the manufacturing process, a simulation model is developed with which the mechanical properties of newly developed compounds with anisotropic additives can be calculated without material testing. Based on mechanical investigations and solubility tests, the potential of the bonding is shown. Important influencing variables are identified and relevant process parameters and limits for the production of plain bearings are also determined. An optimisation of the layer structure of the support shell is carried out in feedback with the calculated mechanical properties of the sliding layer compounds. The stacking sequence of the layers is calculated on the basis of the occurring bearing forces and the overall design of the system is carried out. All the knowledge gained is combined in the process development, from which a manufacturing process for the plain bearings is derived. Bearings are then manufactured and tested to validate the concept. Thus, this work finally shows an overall design including the associated manufacturing process of the new type of plain bearing

Developments and Properties of Plastic Mimicking Biopolymers for Food Packaging Application

Sustainability takes an ever increasing importance in the food industry. Here not only the selection of raw materials plays a role, but also packaging materials. Nowadays there is an increasing number of biodegradable and bio-compostable packaging materials available. However, these materials are still not able to replace mineral oil based packaging materials completely, nevertheless they are becoming increasingly important, since there must be solutions to problems such as pollution of the oceans by plastic waste, growing piles of rubbish from growing population, etc. The following literature review shows briefly recent developments on plastic mimicking biopolymers, as these materials guarantee great potential in itself and a future wider application in the food industry. The presented biopolymers were systematically classified according to their origin (plant, animal, microbial), and special emphasis have been placed on packaging properties. Finally, a forecast for the most promising materials and trends will be presented

Using transient energy release measurements for the in‐line characterization of non‐Newtonian fluids and fluid state in pipe flow

Alberini et al. have developed a new technology based on a passive acoustic emission (AE) sensing system that uses only a single sensor, with the goal of providing live and in-situ measurement of rheology. For this study, three different types of fluids were selected to represent common rheological behaviours: Newtonian behaviour, non-Newtonian behaviour with power law, and non-Newtonian behaviour with Herschel-Bulkley relationship. By analyzing the transient energy released during the interaction between the probe and the fluid, distinct acoustic fingerprints were identified in the frequency domain. These acoustic fingerprints were found to be characteristic of the different fluids and their rheology, and were validated in triplicate. Furthermore, the results showed that the intensity of the acoustic emissions increased with higher flow rates (30 to 50 L/min). To test the correlation between flow rate and acoustic response, a neural network regression test was conducted, which demonstrated a direct correlation between AE peaks and flow rate. The neural network used was nonlinear autoregressive network with exogenous inputs (NARX), and the test involved a stepwise regression with 70% training and 30% network validation. The study also introduced the Rheology-AE quotient, which maps fluid constituents against the acoustic signal. Results showed that this was a reliable means of deriving live rheology from a fluid's frequency domain. Finally, the results obtained from this study were validated using an offline rotational rheometer

Characterising the mechanical properties of soft solids through acoustics and rheology, exemplified by anhydrous milk fat

Foods vary in their elastic properties over a wide range of behaviours. In the case of mastication, textures vary from hard solid through brittle (chocolate bar) and crispy/crunchy (biscuits) to viscous and extensional flow (syrup) and finally very low viscosity fluid (water). Here we deploy an elastic description of soft solids which embraces all these behaviours to quantify the elastic behaviour of food, in particular through the use of sound. We illustrate the use of this mathematical description in the quantitative characterisation of the elastic and flow properties of food through orthodox measurement techniques and novel ultrasound methods. Measurement is complicated by human sensory capabilities that span the entire range from solid to fluid to gas in an integrated manner, during the appreciation of food. We use acoustic and rheological measurement techniques for the determination of the mechanical properties of soft solids, comparing oscillatory rheometry with acoustic parameters as exemplified by acoustic and oscillatory rheometry measurements in crystallising anhydrous milk fat (AMF). We conclude that acoustic and rheological measurements complement each other with acoustic techniques offering the possibility of inline, in process determination of mechanical and flow properties such as viscosity, rigidity, compressibility and bulk modulus

Development Of A Taxonomy On Services Of General Interest

Services of general interest (SGI) are the lifelines for maintaining cities and municipalities. Processes within industrial supply chains intersect with SGIs. For example, concurring resources in terms of utilizing the same delivery routes often lead to delays due to traffic jams, resulting in preventable failure of the business target achievement. In times of endeavors for data-driven solutions, intercompany exchange of data provides new forms of value creation. Considering the example of industrial supply chains, exchanging data between industrial companies and companies offering SGI could help to make an ad-hoc adjustment of the mutual utilization for shared resources. However, potentials of these approaches are overshadowed by hurdles and challenges in offering data. Reasons are for example a lack of data quality, uncertainty of data privacy or regulatory restrictions of revealing data. In addition, the providers of SGIs are usually organized as municipal companies, which are reliant on public funding with budgetary constraints and therefore have limited resources available for innovation, especially for data utilization and applying artificial intelligence. Thus, subsets of practicable use cases tailored for SGI providers need to be identified. In this paper, we develop a taxonomy for services of general interest and their respective providers. Following a systematic literature review, we propose characteristics and dimensions relevant for classifying companies offering SGI. Based on the proposed taxonomy, companies can locate their initial conditions by specifying their issues and use cases. Moreover, identified patterns evoked by utilizing the taxonomy provide the impetus to form new communities dealing with the elaboration on data-driven and AI-based solutions empowerment, serving companies offering SGIs to raise new forms of value and efficiency

Uncovering Interrelationships In MRO-Related Industrial Service Delivery Employing Interpretive Structural Modeling

Maintenance, repair, and operation (MRO) related services for industrial machinery represent a crucial factor in ensuring smooth operations in manufacturing companies. However, the complex interrelationships between a range of factors in the MRO service delivery process often pose significant challenges for industrial service providers, especially in context of digital platforms. This paper utilizes interpretive structural modeling (ISM) to uncover these interrelationships and offers insights for improving service delivery. The hierarchical structure of the interrelationships between the factors helps service providers to identify critical factors that impact their service delivery and develop innovative strategies to optimize these. This paper combines theoretical rigor with expert interviews to provide new insights relevant to practice. By utilizing five variables from service deployment literature, (1) reliability, (2) timeliness, (3) range of services, (4) service quality, and (5) efficiency, divided into their service object and service activity related attributes, the analysis reveals a strong hierarchy among the variables, identifying important dependent and independent factors, as well as important mediators. Overall, the derived structural model serves as a starting point for future quantitative research in the field of service provision

Emphasizing a Service Phase Perspective for Machine Manufacturers Seeking Digital Servitization - a Taxonomy for Industrial Service Phases

The ongoing shift to solution-oriented business models and growing digitalization lead to an increasing importance of services in manufacturing industry. Machine manufacturers in particular struggle to grasp the extent of transformational impact enabled or required by service developments. This is due to a narrow perspective on specific service characteristics, but not on the entire service process. Therefore, a service-dominant perspective is essential in the value creation of manufacturers, placing relevant service phases in the foreground. However, the process-related character of services is rarely considered in the literature. For this purpose, this study provides a taxonomy that classifies services based on phases. In addition to a systematic literature analysis, this study builds on practical insights by conducting eight expert interviews. The applicability and usefulness of the taxonomy is then demonstrated through exemplary application based on a case study, enabling practitioners to adopt a phase-oriented perspective on digital servitization

Amplification of asynchronous inhibition-mediated synchronization by feedback in recurrent networks

Synchronization of 30-80 Hz oscillatory activity of the principle neurons in the olfactory bulb (mitral cells) is believed to be important for odor discrimination. Previous theoretical studies of these fast rhythms in other brain areas have proposed that principle neuron synchrony can be mediated by short-latency, rapidly decaying inhibition. This phasic inhibition provides a narrow time window for the principle neurons to fire, thus promoting synchrony. However, in the olfactory bulb, the inhibitory granule cells produce long lasting, small amplitude, asynchronous and aperiodic inhibitory input and thus the narrow time window that is required to synchronize spiking does not exist. Instead, it has been suggested that correlated output of the granule cells could serve to synchronize uncoupled mitral cells through a mechanism called "stochastic synchronization", wherein the synchronization arises through correlation of inputs to two neural oscillators. Almost all work on synchrony due to correlations presumes that the correlation is imposed and fixed. Building on theory and experiments that we and others have developed, we show that increased synchrony in the mitral cells could produce an increase in granule cell activity for those granule cells that share a synchronous group of mitral cells. Common granule cell input increases the input correlation to the mitral cells and hence their synchrony by providing a positive feedback loop in correlation. Thus we demonstrate the emergence and temporal evolution of input correlation in recurrent networks with feedback. We explore several theoretical models of this idea, ranging from spiking models to an analytically tractable model. © 2010 Marella, Ermentrout

Transient Energy Released by a Tribological Process

This study investigates the relationship between transient energy releases and friction phenomena. We developed a theoretical framework to quantify frictional heating dynamics and transient energy dissipation at sliding interfaces, linking these processes to measurable acoustic emission (AE) waveforms. We identified three distinct AE regimes: (1) 300 kHz signals from micro-crack events, (2) 800 kHz asperity impacts with harmonic frequencies, and (3) broadband stick–slip chirps reflecting friction instabilities. For lubricated contacts, the model demonstrates how viscous damping alters energy release patterns. Key findings reveal that AE frequency content relates with interfacial mechanisms, namely subsurface fracture, elastic asperity collisions, and velocity-dependent friction transitions