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Jet engines of airplanes are designed such that in some components damage occurs and accumulates in service without being critical up to a certain level of damage. Since maintenance, repair, and component exchange are very cost-intensive, it is necessary to predict efficiently the component lifetime with high accuracy. A former developed lifetime model, based on interpolated results of aerodynamic and structural mechanics simulations, uses material parameters estimated from literature values of standard creep experiments. For improved accuracy, an experimental procedure is developed for the characterization of the short-time creep behavior, which is relevant for the operation of turbine blades of jet engines. To consider microstructural influences resulting from the manufacturing of thin-walled single crystal turbine blades, small-scale specimens from used turbine blades are extracted and tested in short- and medium-time creep experiments. Based on experimental results and literature values, a creep model, which describes the fracture behavior for a wide range of creep loads, is calibrated and is now used for the lifetime prediction of turbine blades under real loading conditions., Flugzeugtriebwerke sind so ausgelegt, dass in einigen Komponenten während des Betriebs Schädigungen auftreten und akkumulieren können, ohne dass diese kritisch werden. Wegen der hohen Kosten von Wartung, Reparatur und Austausch ist es notwendig, die Lebensdauer der Komponenten möglichst effizient und genau vorherzusagen. Ein vorab entwickeltes Lebensdauermodell, welches auf interpolierten Ergebnissen von aerodynamischen und strukturmechanischen Simulationen basiert, nutzt in der Literatur verfügbare Daten aus Standard-Kriechversuchen. Um die Genauigkeit der Lebensdauervorhersage zu verbessern, wird eine Versuchstechnik zur experimentellen Charakterisierung des betriebsrelevanten Kurzzeit-Kriechverhaltens entwickelt. Mikrostrukturelle Einflüsse aus der Herstellung der dünnwandigen einkristallinen Turbinenschaufeln werden berücksichtigt, indem die Proben für die Kriechversuche aus gebrauchten Turbinenschaufeln extrahiert werden. Mit den Daten von Kriechversuchen mit kurzen bzw. mittleren Standzeiten wird nun das Lebensdauermodell kalibriert, so dass für einen weiten Bereich von Kriechlasten das Bruchverhalten von Turbinenschaufeln unter Betriebsbedingungen erfasst wird.

Background and aims We were interested to know if laboratory screens of root growth could be used to predict root performance and grain yield of wheat when grown in the field. A secondary aim of this work was to explore the relationship between root depth and grain yield. Methods We screened 637 wheat lines, composed of elite as well as a limited number of breeding lines, to identify wheat lines with contrasting young root traits with a high throughput screen. We selected groups of wheat lines based on the size of the seedling root, root diameter and growth angle. Seventy-two wheat lines were subjected to further screening with a wax-layer screen and grown in a field experiment in two successive years. Root length distributions, from field grown wheat, were determined with the core-break method. Results We were unable to find relationships between data from the laboratory root screens and root depth in the field. In the field, wheat lines with deep roots always had high grain yields, but deep roots were not essential to obtain high yields. Wheat lines with the deepest roots were also amongst those with the greatest number of shallow roots. Conclusion Laboratory root screens did not predict root depth in the field. Root diameter, for reasons that are not clear, is correlated with high grain yield.