["Elastic osteosynthesis" with autocompression plates of carbon fiber reinforced thermoplastic material].
The problem of atrophic bone that occurs in osteosynthesis employing rigid plates is first depicted. Attempts at fabricating "simirigid" plates, which, however, have so far failed to gain any practical importance are then discussed. The reason for this seems to be that made of duroplastics cannot be molded during the operation and the thermoplastics do not have sufficient strength. The production of semirigid plates made of thermoplastic Polyethersulfon (PES), reinforced with 20% short carbon fibres, results in plates which are made moldable by heating in a small oven, white retaining sufficient static strength, although only limited fatigue strength. Biomechanical examinations revealed that with appropriate dimensioning of the plates, "elastic osteosynthesis" results in less loss of mechanical function of the stabilized bones, so that less atrophy of the bone may be expected. During more pronounced exercise loading, a reversible "springiness" of the fracture results, which might stimulate callus formation and improved stability.
Verträglichkeit implantatgeeigneter alloplastischer Werkstoffe im Organismus
Die Bedeutung von Implantaten zur Wiederherstellung von Korperfunktionen, die durch Krankheit, naturliche Abnutzung oder Unfall verlorengegangen sind, nimmt stetig zu und last sich am einfachsten anhand des grosen Bedarfs ermessen. Jahrlich werden mehr als 1 500 000 Personen mit Gefasprothesen versorgt, in 100 000 Fallen werden kunstliche Herzklappen eingesetzt, etwa 220 000 Patienten erhalten einen implantierbaren Herzschrittmacher. Fur die extrakorporale Zirkulation bei Operationen am Herzen werden jahrlich etwa 600 000 Oxygenatoren benotigt. Der Jahresbedarf an kunstlichen Nieren nahert sich der Zahl 1 000 000. Beim Gelenkersatz steht die Huftprothese mit ca. 350 000 Implantationen an erster Stelle vor dem Ersatz des Finger-, Knie-, Schulter- und Ellenbogengelenks. Implantierbare Materialien fur die rekonstruktive Chirurgie haben den Umfang vieler Tonnen erreicht. Einen Eindruck von den vielfaltigen Einsatzgebieten moderner Kunststoffe vermittelt Tabelle 1.
Evaluation of buckling load and dynamic performance of steel shear wall retrofitted with strips made of shape memory alloy
One of the most imperfections of the steel shear wall is out of plane displacements that cause severe damage in both structural and non-structural elements. In this paper, the effects of shape-memory alloys on steel shear walls are investigated. First, a numerical analysis using the finite element method in ABAQUS software has been carried out according to an experimental test. The results of the numerical analysis have been verified with experimental results. Next, shape-memory alloy fibers have been added vertically and horizontally to various parts of the steel shear wall. The results show that retrofitting with the shape-memory alloy reduces the out-of-plane displacement of the steel shear wall under both cyclic and seismic loadings. Besides, the buckling load in the steel shear wall increases when it is retrofitted with the shape-memory alloy. Also, the total out-of-plane movement (accumulated absolute displacements) of the steel shear wall and non-structural damage are controlled by the characteristic of a shape-memory alloy material called “super-elastic”.