Thesis (M.M.S.E.)--University of Delaware, 2008. / Principal faculty advisor: John F. Rabolt, Dept. of Materials Science & Engineering. Includes bibliographical references.

Seile aus synthetischen Fasern gewinnen zunehmend an Bedeutung für fördertechnische Anwendungen. Wegen ihrer geringen Dichte und Biegesteifigkeit sowie den gleichzeitig mit Stahl vergleichbaren Zugfestigkeiten, haben sich Seile aus ultrahochmolekularen Polyethylenfasern (UHMW-PE) in vielen Anwendungen in der Seefahrt und im Offshore-Bereich durchgesetzt. Die grundsätzliche Eignung solcher Seile für technische Anwendungen, wie z.B. Kräne, Aufzüge, Windenanwendungen, wurde in wissenschaftlichen Studien bereits nachgewiesen. In der vorliegenden Arbeit werden hochfeste Polyethylenfasern verschiedener Hersteller daraufhin untersucht, in wie weit diese durch ihre Eigenschaftsprofile ebenfalls grundsätzlich für technische Anwendungen mit auftretenden Biegewechselbelastungen geeignet sind und welche Anwendungspotentiale sie bieten. Beginnend mit einem kurzen geschichtlichen Abriss über die Entwicklung von synthetischen Polymerfasern und den Einsatz der Fasern in Seilen für technische Anwendungen, sollen grundlegend die Herstellungsverfahren und Eigenschaften von Garnen aus ausgewählten UHMW Polyethylen verglichen werden. Im weiteren Verlauf werden Faserseile aus den gewählten Fasern hinsichtlich Zugfestigkeit, Biegewechselverhalten und Eignung zum Thermofixieren untersucht. Auftretende Effekte werden analysiert und auf die Eigenschaften der Fasern bzw. Garne zurückgeführt. Eine vergleichende Betrachtung der Materialkosten als Teil der gesamten Herstellungskosten der Seile bildet den Abschluss der Arbeit. / This thesis covers investigations on the properties of ultrahigh-molecular-weight (UHMW) polyethylene fibers for use of manufacturing braided fiber ropes for conveyor and hoisting applications. The importance of synthetic fibres for conveying applications has increased during the last years. Due to the low density and bending stiffness at a strength that is comparable to steel, ropes made from high-strength UHMW polyethylene fibres have found their ways into several shipping and off-shore applications. The basic aptitude of UHMW polyethylene fibres to be used in applications like cranes, elevators and winch applications has already been proven in scientific works. Within this thesis, selected UHMW polyethylene fibres are investigated to determine how much their differing property profiles do influence their aptitude to be used in technical applications with cyclic bending loads and for which potentials for fields of application they might be appropriate. Starting with a short overview on the history of synthetic fibres and the use of such fibres in technical applications, manufacturing processes and properties of these fibres are to be compared. Further, fibre ropes, made from the selected fibres, are going to be investigated concerning their tensile strength, behaviour in cyclic bend-over-sheave tests and their aptitude to increase the strength by thermosetting. Occurring effects are going to be analysed and related to the properties of the yarns. A competitive view on the prices of the yarns regarding their portion of the total costs of rope manufacturing is finalising this work.

[pt] O presente trabalho investigou o comportamento mecânico de compósitos cimentícios do tipo SHCC (Strain Hardening Cementitious Composites) de resistência comum e alta resistência, reforçados com fibras de PVA, UHMWPE (polietileno de peso molecular ultra-elevado), aço e reforços híbridos. Para o estudo, o volume total de fibras foi mantido constante em 2,0 por cento, com objetivo de manter a trabalhabilidade dos compósitos. As fibras de PVA e polietileno foram parcialmente substituídas por fibras de aço na proporção de 0,5 por cento e 1,0 por cento e a resposta mecânica foi estudada a partir de ensaios de tração direta, flexão de quatro pontos em placas e ensaios de flexão de três pontos em prismas com entalhe. O padrão de fissuração foi analisado utilizando imagens de alta resolução. O efeito escala dos compósitos reforçados com fibras de PVA e polietileno também foi investigado através de ensaios de tração direta e de flexão de quatro pontos utilizando dois tamanhos de corpos de prova. Os resultados mostraram que as fibras de PVA têm melhor desempenho que as fibras de polietileno para matrizes de resistência comum e que para ambas as matrízes, a substituição parcial das fibras de polietileno e PVA por fibras de aço tem o benefício de aumentar a resistência, mas promove redução na capacidade de deformação dos compósitos. O estudo sobre o efeito-escala também mostrou que a resposta mecânica destes materiais muda com a geometria dos corpos de prova. Por último, os compósitos foram utilizados como materiais de reparo estrutural em vigas submetidas a dano prévio e os resultados mostraram a viabilidade da utilização do SHCC como material de reparo. / [en] The present work investigated the mechanical behavior of normal and highstrength Strain Hardening Cementitious Composites (SHCC) reinforced with PVA, UHMWPE (ultra-high molecular weight polyethylene), steel and hybrid fibers. For the study, the total volume of fibers was kept constant at 2.0 percent in order to maintain the workability of the composite system. PVA and polyethylene were partially replaced by steel fibers in 0.5 percent and 1.0 percent. The mechanical response was measured under direct tension tests, four-point bending tests on plates and three point-bending tests on notched specimens. The crack pattern was investigated using high resolution image capturing procedure. The size-effect of the composites reinforced with PVA and polyethylene fibers was also investigated under direct tension test and four-point bending tests using two sizes of specimens. The results have shown that PVA fibers have a better performance than polyethylene fibers for normal strength matrices and that for both normal and high strength matrices the partial replacement of polyethylene and PVA fibers by steel fibers has the benefit of increasing the strength, but it reduces the strain capacity of the composites. The investigation about the size-effect also have shown that mechanical response of these composites changes with the geometry of the specimens. Finally, the composites were used as structural repair in beams subjected to previous damage and the results verified the feasibility of SHCC as a repair material.

Seile aus synthetischen Fasern gewinnen zunehmend an Bedeutung für fördertechnische Anwendungen. Wegen ihrer geringen Dichte und Biegesteifigkeit sowie den gleichzeitig mit Stahl vergleichbaren Zugfestigkeiten, haben sich Seile aus ultrahochmolekularen Polyethylenfasern (UHMW-PE) in vielen Anwendungen in der Seefahrt und im Offshore-Bereich durchgesetzt. Die grundsätzliche Eignung solcher Seile für technische Anwendungen, wie z.B. Kräne, Aufzüge, Windenanwendungen, wurde in wissenschaftlichen Studien bereits nachgewiesen. In der vorliegenden Arbeit werden hochfeste Polyethylenfasern verschiedener Hersteller daraufhin untersucht, in wie weit diese durch ihre Eigenschaftsprofile ebenfalls grundsätzlich für technische Anwendungen mit auftretenden Biegewechselbelastungen geeignet sind und welche Anwendungspotentiale sie bieten. Beginnend mit einem kurzen geschichtlichen Abriss über die Entwicklung von synthetischen Polymerfasern und den Einsatz der Fasern in Seilen für technische Anwendungen, sollen grundlegend die Herstellungsverfahren und Eigenschaften von Garnen aus ausgewählten UHMW Polyethylen verglichen werden. Im weiteren Verlauf werden Faserseile aus den gewählten Fasern hinsichtlich Zugfestigkeit, Biegewechselverhalten und Eignung zum Thermofixieren untersucht. Auftretende Effekte werden analysiert und auf die Eigenschaften der Fasern bzw. Garne zurückgeführt. Eine vergleichende Betrachtung der Materialkosten als Teil der gesamten Herstellungskosten der Seile bildet den Abschluss der Arbeit. / This thesis covers investigations on the properties of ultrahigh-molecular-weight (UHMW) polyethylene fibers for use of manufacturing braided fiber ropes for conveyor and hoisting applications. The importance of synthetic fibres for conveying applications has increased during the last years. Due to the low density and bending stiffness at a strength that is comparable to steel, ropes made from high-strength UHMW polyethylene fibres have found their ways into several shipping and off-shore applications. The basic aptitude of UHMW polyethylene fibres to be used in applications like cranes, elevators and winch applications has already been proven in scientific works. Within this thesis, selected UHMW polyethylene fibres are investigated to determine how much their differing property profiles do influence their aptitude to be used in technical applications with cyclic bending loads and for which potentials for fields of application they might be appropriate. Starting with a short overview on the history of synthetic fibres and the use of such fibres in technical applications, manufacturing processes and properties of these fibres are to be compared. Further, fibre ropes, made from the selected fibres, are going to be investigated concerning their tensile strength, behaviour in cyclic bend-over-sheave tests and their aptitude to increase the strength by thermosetting. Occurring effects are going to be analysed and related to the properties of the yarns. A competitive view on the prices of the yarns regarding their portion of the total costs of rope manufacturing is finalising this work.