Microstructures on polymer surfaces are known to reduce friction and thevisibility of scratches. Due to the complex interaction of multiple surface areas in contactwith each other the prediction of coefficient of friction (COF) or wear is difficult and dependson an empirical solution. This article deals with possibilities of calculating the deformingpart of friction via an analytical solution and a FE-model. In a first step the modelling ofsingle contacts is demonstrated. The analytical calculation based on the Hertzian contactequations is extended regarding viscoelastic material parameters. The basic approach ofFE-modelling is explained including calibration of the material model using the softwareMCalibration®. The article introduces the different procedures of simulating and modellingCOF and wear taking into account the area of contact and resulting stress distribution.
Steel wire ropes have established as transmission, connection and safety elements in transporters such as cranes and elevators, due to their high breaking strength and operational safety as well as out of many years of experience. However, steel wire ropes have disadvantages such as high dead weight, high bending stiffness and sensitivity to corrosion. Increasing requirements on the energy-efficient and resource-saving operation of technical systems demand new materials, technologies and processes. As a result, textile machine elements like HM-HT fibre ropes (high modulus, high tenacity) come into focus of considerations. The aim of the research is to expand the level of knowledge with regard to the state of wear and aging. Another aim is to find out the influencing factors on the lifetime, discard criteria of high-strength fibre ropes and to derive methods for lifetime detection.
Der Klimawandel zeigt sich u.a. in Form von Hochwasserkatastrophen, wie zuletzt 2021 im Ahrtal, und ist besonders in Städten mit zunehmender Flächenversiegelung spürbar. Doch bevor ein Hochwasser in den Stadtkernen bemerkbar wird, können Schutzmaßnahmen insbesondere an den Deichen vorgenommen werden. An der Professur Förder- und Materialflusstechnik (FTM) an der TU Chemnitz wurde ein Forschungsvorhaben innerhalb des BMBF-Programms „Forschung für die zivile Sicherheit 2012–2017“ ausschließlich für die Sicherung von Flussdeichen durchgeführt. Im Rahmen des Projekts wurden auf Basis technischer Textilien sowie der Fördertechnik innovative Lösungen geschaffen, um somit die Sicherheit der Bürgerinnen und Bürger zu erhöhen und eine anwendungsorientierte Forschung unter Einbeziehung der Endnutzer voranzutreiben (Bild 1).
In Transport- und Verkettungsprozessen werden zunehmend Stetigförderer mit Ketten aus technischen Thermoplasten, vorzugsweise aus Polyoxymethylen (POM), hergestellt. Verschlissene Ketten, die sich im Schnitt ca. 2-10 Jahre im industriellen Einsatz unter verschiedensten Belastungs- und Umgebungsbedingungen befinden, werden ausgetauscht und derzeit ausschließlich im Restmüll entsorgt. Im Beitrag werden die mechanischen und tribologischen Eigenschaften von homo- und copolymerem POM bei mehrfacher Verarbeitung sowie Vermischung der Materialtypen analysiert. Auf dieser Grundlage wurde ein Rezyklat aus mehrjährig in industriellen Anwendungen gelaufenen POM-Ketten hergestellt und daraus Proben und Förderketten für weitere Untersuchungen gefertigt. Es wird gezeigt, dass die wertvollen Kunststoffe durchaus erfolgreich recycelt und wieder zu neuen Bauteilen verarbeitet werden können. In transport and linking processes, continuous conveyors with chains made of engineering thermoplastics, preferably polyoxymethylene (POM), are increasingly being used. Worn chains, which are used in industrial applications for an average of 2-10 years under a wide variety of load and environmental conditions, are replaced and currently disposed of in the residual waste. The article analyses the mechanical and tribological properties of homo- and copolymeric POM during multiple processing and blending of the material types. Based on this, a recyclate was produced from POM conveyor chains that had been used in industrial applications for several years. Samples and chains were made from this material for further investigations. It is shown that the valuable plastics can be successfully recycled and reprocessed into new components.
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