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Rotational moulding for small diameter continuous fibre reinforced thermoplastics structures
No full textContinuous-reinforced thermoplastic composites are becoming increasingly important for mass production of lightweight components across various industrial sectors. This paper describes a novel process chain for the production of continuous fibre reinforced thermoplastic matrices with a rotationally symmetric cross-section, using rotational moulding technology. The process chain is based on wound and pre-consolidated preforms, which are then formed into the final geometry by rotational moulding. To support the manufacturing of smaller diameters, a composite core is used to increase the pressure during manufacture. The experimental results are examined by cross-sectional micrographs and show the approach’s feasibility
Teilentladungsdiagnostik an umrichterbetriebenen elektrischen Maschinen im Niederspannungsbereich
No full textDie Teilentladungsdiagnostik bei rechteckförmigen Prüfspannungen ist aufgrund transienter Störphänomene anspruchsvoll. Zur Reduzierung dieser Einflüsse erfolgt die Erfassung der Teilentladungen (TE) in dieser Arbeit im höheren Frequenzbereich. Hierfür entwickelte leistungselektronische Prüfquellen können realitätsnahe Rechteckspannungen mit Frequenzen bis zu 100 kHz bei variabler Spannungsanstiegsgeschwindigkeit erzeugen und ermöglichen so die gezielte Analyse der Auswirkungen von Schaltvorgängen auf das Isoliersystem. Die Spannungsverteilung innerhalb der Wicklung ist dabei nichtlinear. Durch die Kombination von experimentellen Untersuchungen an Asynchronmaschinen und der theoretischen Modellierung ihrer Isoliersysteme im Hochfrequenzbereich lassen sich Entladungsstellen lokalisieren und den tatsächlichen Spannungspegeln zuordnen. Diese Erkenntnisse bilden eine wichtige Grundlage für die Weiterentwicklung praxistauglicher TE-Diagnoseverfahren für umrichtergespeiste Antriebe
Mapping the supply of nature’s contributions to people on Mount Kilimanjaro
No full textMount Kilimanjaro, with its steep elevational gradient (770–5886 m a.s.l.) and pronounced land-use heterogeneity, supports high biodiversity and diverse nature’s contributions to people (NCP), but it is underrepresented in global spatial assessments. We address this gap by mapping NCP supply across 12 ecosystem types on the southern slopes identifying hotspots and coldspots and quantifying synergies and trade-offs among NCP categories. We use 25 context-specific NCP categories that integrate local and scientific knowledge with field measurements and remote-sensing-derived proxies. Combining long-term field data with remote sensing and machine learning, we upscaled plot-scale indicators into standardized supply maps. Total NCP supply is strongly concentrated in mid-elevation ecosystems: the 1100–2200 m band alone accounted for ∼59% of total supply compared with ∼18% in the lowlands (700–1100 m), and the 1100–2800 m belts together provide ∼73%, whereas high-elevation zones (2800–4600 m) contribute <9%. Hotspots clustered in lower montane forest, Ocotea forest and homegardens at mid-elevations, while coldspots occur in Erica forest and Helichrysum vegetation at high elevations and in maize fields and savanna at low elevations. We detected moderate (r = 0.55) to strong synergies (r = 0.83) among the three NCP groups (material, regulating, non-material). After accounting for climatic co-variation, the correlations among NCP groups weakened (r = 0.23–0.44), underscoring the critical role of climate for NCP supply. Our study maps NCP hotspots and coldspots across Mt. Kilimanjaro and provides a decision-support layer for conservation, restoration and agroforestry management, as well as a blueprint for spatially-explicit NCP mapping and analyses
Vorstellung einer sensorintegrierten Schraube zur Bestimmung der Gesamtzusatzspannung Presentation of a sensor-integrated bolt for determining the total additional stress
No full textA newly developed sensor-integrated bolt is presented that is capable of measuring both axial
force and bending moment in the bolt shaft. The solution presented integrates four strain
gauges into the bolt shaft without significantly altering the mechanical properties of the bolt.
The new evaluation method presented for the three non-centrically positioned strain gauges
makes it possible to determine the total additional stress in the bolt connection
Vorhersage der subjektiven Vibrationsbewertung als Grundlage für die Mensch-Maschine Symbiose
No full textZukunftsorientiert forscht das IPEK nach dem Leitbild „Industrie 5.0“ der Europäischen Kommission an einer neuen Entwicklungsstufe der physischen MenschMaschine-Interaktion, in welcher beide Akteure gemeinsam und sich ergänzend eine Aufgabe ausführen. In dieser sog. Mensch-Maschine Symbiose sind Mensch und Maschine in der Lage, gegenseitig die nächsten Handlungsschritte zu prädiktieren und sich Feedback über Leistungsparameter sowie der Wahrnehmung zu geben. Damit eine echte Kollaboration entstehen kann und die jeweiligen Stärken ausgespielt werden können, ist ein genaues Verständnis über die komplexe Mensch-Maschine Interaktion notwendig. Der Mensch stellt mit seinen stark individuellen physischen, physiologischen und psychologischen Eigenschaften eine große Herausforderung in hierfür notwendigen Analysen dar. Viele Wechselwirkungen beeinflussen die menschliche Wahrnehmung und Bewertung, sodass die Ableitung einer objektivierbaren, validen und reproduzierbaren Größe über viele Probanden eine sehr schwierige Aufgabe darstellt. Erstmals ist es im Rahmen der Industriellen Gemeinschaftsforschung (IGF), innerhalb des Projekts Objektive Bewertung Vibrationskomfort (OBAS), gelungen, eine objektive Größe für die subjektive, frequenzabhängige Bewertung des Vibrationsdiskomforts für Hand-Arm-Vibrationen abzuleiten
Decoding of Postperformance Nonverbal Behavior of Tennis Players: Is a Shorter Response Time Associated With Higher Accuracy?
No full textThe decoding of nonverbal behavior is thought to be influenced by both bottom-up automatic perceptual and top-down higher order cognitive processes. In this study, we aimed to provide initial evidence for the association between response time and accuracy, as a first step toward understanding how such processes may operate. To that end, 145 individuals (66 female; Mage = 32.18) were presented 80 videos of amateur tennis players\u27 nonverbal behavior directly after the rally. After each video, the participants were asked to estimate whether the previous point was won or lost. The results showed that the response time was about a half second faster for correct (M = 3,052.78 ms, SD = 840) than for incorrect (M = 3,567.77 ms, SD = 1,048.15) responses. These findings provide first evidence that faster responses are related to greater accuracy, suggesting that efficient, possibly more intuitive processes may facilitate decoding in this context
Do you speak LCA? FAULDIER: A framework for large language model assisted Life Cycle Inventories in Life Cycle Assessment
No full textAdvances in Life Cycle Assessment (LCA) toward greater automation and methodological integration have intensified challenges in standardizing heterogeneous raw Life Cycle Inventory (LCI) data, which rarely aligns with LCI database nomenclature. Rule-based mapping approaches struggle with linguistic variations, typographical errors, unit inconsistencies, and location granularity mismatches. Furthermore, they fail to adapt automatically when data or terminology change. FAULDIER (Framework for lArge langUage modeL assisteD lIfe cyclE inventoRy) is proposed as a framework to bridge heterogeneities between raw LCI data and LCI database requirements. It aims to automate data transformation by resolving naming inconsistencies, classifying flow types, and harmonizing locations and units. By using LLMs, FAULDIER supports handling multilingual inputs, correcting typographical errors, resolving location granularity mismatches, and choosing proxies for missing processes. In a test scenario using the open LCI database FORWAST and a use case characterized by non-standardized multilingual entries, unit inconsistencies, and typographical errors, FAULDIER achieved approximately 57% process and elementary flow mapping accuracy (single-expert validated), with unit conversion error rates below 1%. Current limitations include LCI database constraints, LLM token limitations, performance variability of open-weight LLMs, mapping ability, and reproducibility across runs. Within these limitations, FAULDIER indicates the feasibility of LLM-assisted LCI construction for LCA modeling, particularly for non-standardized raw LCI data. Future work could focus on developing confidence metrics for mapped LCI data, optimizing LLM query efficiency, and expanding testing across additional LCI databases, use cases, and LLMs
Locations of cleavage initiation sites in miniaturized C(T) specimens and their relation to mechanical field quantities
No full textThe miniaturized C(T) specimen is a promising geometry to be used in future surveillance programs for the long-term operation of second-generation nuclear reactors. In multiple studies, the geometry was shown to provide Master Curve reference temperature values comparable to standard-sized C(T) specimens. International testing standards such as ASTM E1921 additionally require cleavage fracture to occur under high constraint conditions. Due to its reduced thickness, constraint loss is observed in the miniaturized C(T) specimen at high crack tip loads. In order to validate the miniaturized C(T) geometry, it must be ensured that cleavage initiation still occurs under similar conditions as with standard-sized C(T) specimens.
In this study, the locations of cleavage initiation sites in miniaturized C(T) specimens of SA-508 Cl.3 reactor pressure vessel steel are determined by means of scanning electron microscopy. Applying finite-element-analysis, the mechanical fields in front of the crack tip, namely the maximum principal stress, stress triaxiality and equivalent plastic strain, are obtained. By relating the locations of the initiation sites to the mechanical field quantities, the conditions for cleavage fracture are deduced. Particular attention is paid to the stress triaxiality, which is used as a measure of crack tip constraint. The mechanical fields of miniaturized specimens are compared to standard-sized geometries to evaluate similarities and differences in the fracture behavior based on the load level. It is shown that cleavage fracture initiation in miniaturized specimens remains located within a region of high crack tip constraint, even when significant macroscopic plastic deformation occurs prior to failure. Consequently, the conditions for cleavage initiation are found to be similar in miniaturized and standard-sized C(T) geometries
