Einsatz bruchmechanischer Methoden zur Bestimmung der Restnutzungsdauer von Windenergieanlagen

Application of fracture mechanics to the assessment of remaining life‐span of wind turbines. The assessment of cracks in steel tube towers of wind turbines by using models based on fracture mechanics is described. The presented concept can be used to determine the remaining life‐span of wind turbines. Maximum allowable crack dimensions are determined. Growth of the cracks up to these critical dimensions is investigated. For that purpose semi elliptic surface cracks are assumed in the welded joint between door frame and tower hull. Solutions for the stress intensity factor are used to describe the stress field at the crack tip. Input stresses are determined by linear‐elastic finite element calculation. The Failure Assessment Diagram (FAD) is used to determine critical crack dimensions. Crack growth is estimated considering stress ratio and s‐shaped dependency of crack growth rate on cyclic stress intensity.     

Optimierung geothermischer Energiesysteme am Beispiel eines städtebaulichen Entwicklungsvorhabens

Optimization of geothermal energy systems with an urban developement project. With an example of an urban development projekt in Bottrop‐Kirchhellen, Germany, a complete supply of a new urban district with geothermal energy will be presented. By thermal building simulations the heating load profiles of the buildings were determined and linked to geothermal simulations. However, the swaying of the heating loads in the buildings does not fit to the nearly constant heat flow from the ground. Hence, the profile of the loads should be smoothed by a combination of different heating systems and by the use of storage devices for an efficient use of geothermal energy.     

Batch-Versuche zur Bestimmung der Sorption und Reaktionskinetik von fluoreszierenden Tracern

Grundwasser - Für viele Tracerversuche ist eine vorherige Bestimmung der Interaktion zwischen durchflossenem Medium und einzusetzenden Tracern im Labor von hohem Interesse, um eine effiziente,...     

Tiefenorientierte Pumpversuche zur Bestimmung der hydraulischen Anisotropie in einem geschichteten Grundwasserleiter

Grundwasser - Die horizontale Schichtung von Sedimentkörpern bewirkt, dass die effektive hydraulische Durchlässigkeit eines sedimentären Grundwasserleiters in horizontaler Richtung...     

Eigenschaften geothermischer Nutzhorizonte im baden-württembergischen und französischen Teil des Oberrheingrabens

The project entitled ?Development of an Internet Based Geothermal System for Germany” includes the design of a geothermal information system for the deep hydrogeothermal resources of Germany. For the first time, hydraulic data from the entire Upper Rhine Graben in Baden-Württemberg and France were collected and interpreted. They give hydraulic conductivities in the geothermal reservoirs of the Hauptrogenstein, Oberer Muschelkalk and Buntsandstein. The mean value of the Hauptrogenstein south of Freiburg is T/H = 1,8?·?10^–6?m/s, and the Oberer Muschelkalk average is T/H = 2,0?·?10^–6?m/s. For the Buntsandstein, the hydraulic conductivity is T/H > 2,4?·?10^–7?m/s. Estimated hydraulic conductivities derived from productivity indices and permeability data are used for further comparative considerations.     

Verfahrensprüfung zur Bestimmung von Anziehparametern für vorgespannte geschraubte Verbindungen

Procedure qualification for the determination of tightening parameters for preloaded bolted connections. DIN EN 1090‐2 and DIN EN 1993‐1‐8/NA define tightening procedures for preloaded bolted assemblies tightened at the nut side by simple use thereof. However, in a multitude of applications, preloaded bolted connections are used, which for example are tightened on the head side, designed as tapped hole connections and/or are to be used several times. In these cases, a procedure test is necessary to determine the tightening parameters. The present paper describes the principal procedure for carrying out such a procedure test, in particular the target level of preloading, the length of thread engagement for components with internal threads, the single and multiple use of components, and the boundary criteria for determining the tightening parameters. Furthermore, the procedure is explained using practical examples.