Biologisch vertraegliche Werkstoffe in der Medizintechnik und Endochirurgie - Literaturrecherche

A review of current biomaterials clinically applied as stems, femoral heads and acetabular cups of total hip prosthese has been made with regard to their mechanical properties, corrosion behaviour and wear resistance. The successful implantation and the life cycle of an endoprosthesis is highly dependent on its connection to the bone bed. Besides the problem of mechanical loading of the prosthesis and the change of the strain condition in cortical bone, the stresses in the bone cement, which act as a force-transmitting element, are of considerable importance. Inadequate cementing technique is often the reason for the loosening of the endoprosthesis. An alternative way of fixation of an endoprosthesis to cementing is the biological connection by the ingrowth of bone into the implant surface. Despite the increasing use of orthopaedic implants, there is still a lack of adequate testing procedures and legal guidelines for testing. Modern testing methods, techniques for the calculation of stresses and life cycle predictions applied during the development and manufacturing phases of standard and special implants, may ensure an adequate prosthetic life cycle with a particular emphasis on the biomedical optimization of the interface implant/bone and the surrounding bone. The mismatch concept applied to the system bone/implant as a composite model is a possible way to optimize biofunctionality and biocompatibility with regard to extending the prosthetic life cycle. (orig.)Available from TIB Hannover: RA 3251(97/E/49) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Fracture toughness behaviour of FSW joints aluminium alloys

The friction stir welding (FSW) process can be successfully used to achieve defect-free joints in Al-alloys. However, a thorough characterisation of the joints is needed in order to satisfy the stringent requirements of advanced applications such as aerospace, automotive and shipbuilding. In this work, FSW was performed on four different aluminium alloys, namely 5005-H14, 2024-T351, 6061-T6, and 7020-T6 (plate thickness being 5 mm except alloy 5005 which is 3 mm thick). The main objective was to establish the local microstructure-property relationships and to determine the fracture toughness levels of welded plates with weld zone strength undermatching. The FSW welds were void and crack free in all of the investigated alloys. Tensile and fracture toughness properties (in terms of CTOD) of the FSW joints were determined at room temperature in addition to extensive hardness measurements and tensile tests. The effects of strength mismatch and local microstructure on the fracture toughness of these joints were discussed. (orig.)First published in: P.L. Threadhill (ed.): First International Symposium on Friction Stir Welding - Proceedings, June 14-16, 1999, in Thousands Oaks, CA, USA. Cambridge, GB: The Welding Institute Ltd, 1999. CD-ROMAvailable from TIB Hannover: RA 3251(2000/42) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

The use of titanium alloys for dynamic risers: a literature review

Die vorliegende kurze Literaturrecherche befasst sich vorrangig mit den materialbezogenen Aspekten der Produktion und des Einsatzes von flexiblen 'Risern' aus Titanlegierungen fuer die Oel- und Gasfoerderung auf See. Die Metallurgie und das Legieren von Titan werden kurz vorgestellt. Die Recherche konzentriert sich im weiteren auf die Materialeigenschaften, die fuer den vorgesehenen Einsatz in mariner Umgebung von besonderer Bedeutung sind. In erster Linie wird dabei auf #alpha#+#beta#-Titanlegierungen eingegangen, da vorausgegangene Untersuchungen gezeigt haben, dass diese Legierungsfamilie die guenstigsten Eigenschaften fuer das vorgesehene Einsatzgebiet aufweist. Im weiteren werden die Schweissprozesse, die bei Titanlegierungen eingesetzt werden, vorgestellt und die Eigenschaften und moeglichen Schweissfehler der hergestellten Schweissverbindungen gegenuebergestellt. Diese Literaturrecherche wurde im GKSS-Forschungszentrum im Rahmen des Projektes 'Titanium Risers for Deepwater Developments' (Vertrags-Nr. OG/175/95) erstellt. Das Projekt wird durch das THERMIE-JOULE-Programm der Europaeischen Kommission gefoerdert. Das Projektkonsortium besteht aus den drei Partnern Stolt Comex Seaway Ltd. (England), Seaflex AS (Norwegen) und GKSS. (orig.)The main topic of this short literature review is to describe the material related aspects concerning the production and purpose of flexible titanium risers for offshore oil and gas production. Metallurgy and alloying of titanium are briefly introduced. The review concentrates on the materials properties that are relevant for the intended use in marine environment. The focus is put on #alpha#+#beta# Ti-alloys, because earlier investigations have shown that this alloy family is the most suitable one for this purpose. Further topics which are taken into account are welding processes for titanium, weld properties and aspects of the associated weld defects as well. This literature review has been carried out at GKSS-Forschungszentrum Geesthacht GmbH within the framework of the project 'Titanium Risers for Deepwater Developments (contract nr. OG/175/95), supported by the THERMIE-JOULE Programme of the European Commission. The project consortium is formed by Stolt Comex Seaway Ltd. (UK), Seaflex AS (Norway) and GKSS (Germany). (orig.)SIGLEAvailable from TIB Hannover: RA 3251(97/E/38) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman