Prozesskette zur Herstellung von hybriden Faser-Metall-Preforms - Modellbildung und Optimierung des Binderauftrags und der Drapierung für stabförmige Bauteile

Hybrid fibre composite-metal rods are suitable for mechanically highly stressed applications due to their high lightweight potential. In terms of multi-material design, the load introduction is made of metal, while the load transmission area is made of composite material. In the state of the art, the rotational moulding process has been qualified as a highly efficient and flexible manufacturing process for intrinsic hybridization for the production of such components. The rotational moulding process can be used to produce highly durable joints between metal and composites. However, a hybrid preform is required before the actual infiltration. This consists of a stabilized, near-net-shape draped fibre preform in which the metallic load introduction elements are already integrated. The process chain for manufacturing hybrid preforms from braided sleeves and the metallic load introduction elements has not yet been investigated and therefore represents the central objective of this work. Furthermore, a continuous process understanding for the process chain shall be achieved. Therefore, in the first step of this work, requirements for the process chain are elaborated and a sequence of individual processes is developed. The individual processes are analysed with regard to their degree of maturity and it is determined that the steps binder application and draping represent the special focus of this work. The individual processes are analysed with regard to their degree of maturity and it is determined that the two steps of binder application and draping represent the special focus of this work. For the binder application, a machine module is developed which is based on the vibration-assisted dispensing of binder powder. For the selection of a suitable dispensing nozzle, a model is developed which predicts the binder dispensing and thus calculates the optimum nozzle configuration. A machine module is also being developed for the draping process step, which drapes the preform onto the load introduction element by means of membrane-based forming with compressed air. A kinematic draping model is developed and validated to determine the necessary axial feed during draping. Finally, a continuous process chain consisting of all individual steps is prototyped, tested and validated on the basis of the requirements set out at the beginning

A Note On Job Market Conditions And Students Academic Performance

This paper presents a model of student effort and resulting grade performance under varying labor market conditions. Following previous studies that have found a negative relationship between the expected income and grades by discipline, we extend the analysis to the effect of changing labor market conditions on student effort and the resulting changes in the average grades. The empirical results support the theoretical models conclusion that reduced employment opportunities result in higher average grades by discipline

Production of hybrid tubular metal-fibre preforms: development of a digital twin for the draping process

Hybrid shafts or rods with a metallic end fitting and a load transmitting area made of fibre reinforced plastics possess a great potential in terms of lightweight design, e.g. in automotive industry or aviation. One essential and quality-defining process step in the manufacturing of such parts is the draping of dry braided fibre fabrics onto the shape of the metallic end fitting. To explore the immature draping process and to derive the draping tool geometry a digital twin based on finite element simulation has been developed and validated by first experiments

Production of Hybrid Tubular Metal-Fiber-Preforms: Material Characterization of Braided Hoses with a Binder

Hybrid shafts or rods, where the area of load introduction is metallic (e.g. steel or aluminium) and the area of load transfer is made of fibre reinforced plastics (FRP), are an established concept for lightweight parts. Besides the monolithic FRP and the metallic areas, the overlap area of both materials is particularly important. Such parts can beneficially be produced by the use of liquid composite moulding (LCM), where the bonding process takes place during the resin curing. This is called intrinsic hybridization. Beforehand it is crucial to produce a near-net-shape preform in which the metallic end fittings for the load introduction are already integrated. To manufacture such parts constantly with a high quality, a process model of the joining by draping the braided preform is necessary. In this paper an approach for the production of hybrid preforms made of braided hoses and metallic fittings is presented in order to develop a process model. The process starts with a cylindrical multi-layer preform made of braided hoses, in which the layers are bonded by a thermoplastic binder powder. The decisive process step is the draping of the preform onto the metallic fitting. For this forming step, the material characterization of the hybrid preform plays an important role. Several material tests to determine the textile parameters of the preform are therefore evaluated and performed. Finally, the results of these tests are presented and discussed

Health status in non-dystrophic myotonias: close relation with pain and fatigue

To determine self-reported health status in non-dystrophic myotonias (NDM) and its relationship to painful myotonia and fatigue. In a cross-sectional study, 32 NDM patients with chloride and 30 with sodium channelopathies, all off treatment, completed a standardised interview, the fatigue assessment scale (FAS), and the 36-item Short-Form Health Survey (SF-36). Beside formal assessment of pain, assessment of painful or painless myotonia was determined. The domain scores of the SF-36 were compared with Dutch community scores. Apart from the relationship among SF-36 scores and (1) painful myotonia and (2) fatigue, regression analyses in both NDM groups were conducted to determine the strongest determinants of the SF-36 domains general health perception, physical component (PCS) and mental component summary (MCS). All physically oriented SF-36 domains in both NDM groups (P ≤ 0.01) and social functioning in the patients with sodium channelopathies (P = 0.048) were substantially lower relative to the Dutch community scores. The patients with painful myotonia (41.9%) scored substantially (P < 0.05) lower on most SF-36 domains than the patients without painful myotonia (58.1%). Fatigued patients (53.2%) scored substantially lower (P ≤ 0.01) on all SF-36 domains than their non-fatigued counterparts (46.8%). The regression analysis showed that fatigue was the strongest predictor for the general-health perception and painful myotonia for the physical-component summary. None of the patients showed below-norm scores on the domain mental-component summary. The impact of NDM on the physical domains of patients’ health status is substantial, and particularly painful myotonia and fatigue tend to impede their physical functioning

Solar ultraviolet radiation and ozone depletion-driven climate change: Effects on terrestrial ecosystems

In this assessment we summarise advances in our knowledge of how UV-B radiation (280-315 nm), together with other climate change factors, influence terrestrial organisms and ecosystems. We identify key uncertainties and knowledge gaps that limit our ability to fully evaluate the interactive effects of ozone depletion and climate change on these systems. We also evaluate the biological consequences of the way in which stratospheric ozone depletion has contributed to climate change in the Southern Hemisphere. Since the last assessment, several new findings or insights have emerged or been strengthened. These include: (1) the increasing recognition that UV-B radiation has specific regulatory roles in plant growth and development that in turn can have beneficial consequences for plant productivity via effects on plant hardiness, enhanced plant resistance to herbivores and pathogens, and improved quality of agricultural products with subsequent implications for food security; (2) UV-B radiation together with UV-A (315-400 nm) and visible (400-700 nm) radiation are significant drivers of decomposition of plant litter in globally important arid and semi-arid ecosystems, such as grasslands and deserts. This occurs through the process of photodegradation, which has implications for nutrient cycling and carbon storage, although considerable uncertainty exists in quantifying its regional and global biogeochemical significance; (3) UV radiation can contribute to climate change via its stimulation of volatile organic compounds from plants, plant litter and soils, although the magnitude, rates and spatial patterns of these emissions remain highly uncertain at present. UV-induced release of carbon from plant litter and soils may also contribute to global warming; and (4) depletion of ozone in the Southern Hemisphere modifies climate directly via effects on seasonal weather patterns (precipitation and wind) and these in turn have been linked to changes in the growth of plants across the Southern Hemisphere. Such research has broadened our understanding of the linkages that exist between the effects of ozone depletion, UV-B radiation and climate change on terrestrial ecosystems

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.

Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field

Les apports de l'analyse structurale à la connaissance des Pyrénées Occidentales

Henry Jacques, Richert Jean-Paul, Ruhland Michel. Les apports de l'analyse structurale à la connaissance des Pyrénées Occidentales. In: Bulletin du Service de la carte géologique d'Alsace et de Lorraine, tome 21, n°3, 1968. Géologie structurale, pétrographie. pp. 135-136