Plauen, Germany
Plauen, Germany

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Grober D.,TU Chemnitz | Leidich E.,TU Chemnitz | Lang H.,Berufsakademie Sachsen | Bruzek B.,TU Chemnitz
Materialwissenschaft und Werkstofftechnik | Year: 2011

As part of the growing interest in the operation reliability of bicycles and their components design strength investigations were performed on a bicycle brake lever of an aluminium casting alloy. In addition to materials testing and FE-analysis the low cycle fatigue straight lines of the two spot samples, which differ in production periods, were determined experimentally. The low cycle fatigue straight line of the second spot sample of the brake levers has in comparison to the first one with a slope exponent of 5.5 a larger gradient. Furthermore this straight line is in the range of larger numbers of cycles. The reason for this is seen in a detectable changed casting quality. In the field of operational stability 2-step-block-tests were accomplished. Using Miner's rule the damage sums of the test results are larger than one. The experimental results are hence in safe area. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fritsch S.,TU Chemnitz | Hockauf M.,TU Chemnitz | Schonherr R.,Berufsakademie Sachsen | Hunger S.,TU Chemnitz | And 2 more authors.
Materialwissenschaft und Werkstofftechnik | Year: 2010

The present study shows first results on the optimization of the mechanical properties of the high strength 7075 aluminium alloy, which is generally regarded as hard to deform. Two different deformation/processing approaches are considered: On the one hand, the equal-channel angular pressing (ECAP) with different types of dies is utilized. On the other hand, (cold) rolling is performed with different, low temperatures (down to -196°C). Various degrees of deformation are realized with both methods. By systematically adjusting the degree of deformation and the deformation temperature, the AA7075 alloy can be processed by ECAP. However, only minor improvements of the mechanical properties can be achieved by this approach. Cryogenic rolling results in a further increase of the degree of deformation, and also of strength and ductility.These results indicate that further improvements of the mechanical properties may well be achieved by ECAP processing at low temperatures. Both ECAP and cryogenic rolling offer a high potential for the production of ultrafine-grained high-strength aluminium alloys with novel properties. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA,Weinheim.

Timber has a high resistivity to chemically aggressive agents. This is one of the reasons why timber structures are frequently being used in the construction of storage halls for chemical materials or of industrial buildings with aggressive environment. In this paper the state of the art of corrosion in timber and the consideration the chemical action by using a modification factor in the limit state design is presented. © 2011 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

Keunecke D.,Institute for Buildings Materials | Niemz P.,Institute for Buildings Materials | Zurich E.T.H.,Institute for Buildings Materials | Tollert M.,Berufsakademie Sachsen | Hansel A.,Berufsakademie Sachsen
Wood Research | Year: 2012

While the longitudinal mechanical behaviour of Common yew is relatively well known, only limited information is available about its behaviour when the load direction is oriented perpendicular to the grain. Thus in this study, a compact tension test was performed on small yew specimens (and on spruce as a reference species) for four different crack orientations. The experiment was supplemented by a digital image correlation system to analyse the strain in fracture process zones on the surface of the samples. Various relevant mechanical parameters (critical load, initial stiffness and fracture toughness) were determined and evaluated. Better mechanical properties were obtained for yew as a result of its higher raw density compared with spruce. Several further characteristics were interpreted against the background of structureproperty relationships.

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