Zeitvariantes Trag‐ und Schädigungsverhalten von mehrfach wiederholt beanspruchtem polymermodifizierten Beton (PCC)

Auf Basis der in Teil 1 beschriebenen Versuchsergebnisse und der visko‐elastisch‐plastischen Kontinuumsschädigungstheorie werden rheologische Modelle zur Beschreibung des zeit‐ und beanspruchungsabhängigen Tragverhaltens von Beton vorgestellt. Die numerische Umsetzung erfolgt unter Berücksichtigung des zeitabhängigen Betonverhaltens auf der Basis des Hamilton‐Prinzips unter Vernachlässigung der Trägheitskräfte. Die Simulation des beanspruchungsabhängigen Tragverhaltens von Stahlbetonverbundquerschnitten verdeutlicht die Qualität und Leistungsfähigkeit der vorgeschlagenen Modellbildung. Ferner werden ausgewählte praxisrelevante Fragestellungen zum zeit‐ und beanspruchungsabhängigen Betontragverhalten numerisch untersucht. Time‐Variant Behaviour of Polymer Modified Concrete (PCC) under Repeated Stress with Consideration of Damage Part 2: Modelling the Behaviour of Concrete Based on experimental results which are described in Part 1 and the theory of visco‐elastic‐plastic continuum damage, rheological models are used to calculate the time‐ and damage‐dependent behaviour of concrete. The numerical concept is based on the Hamilton‐principle. The efficiency of the models was proven by numerical simulation of concrete or reinforced concrete cross sections. In addition, selected practical‐relevant questions about time‐ and load‐dependent behaviour of concrete are numerically investigated.     

Microstructure‐oriented characterisation of the cyclic deformation behaviour of Ti‐6Al‐4V

In this paper, the cyclic deformation behaviour of the titanium alloy Ti‐6Al‐4V is characterised in uniaxial stress‐ and total‐strain‐controlled load increase and constant amplitude tests at ambient temperature by means of mechanical stress‐strain hysteresis and temperature measurements. The measured physical values obviously show a pronounced interrelation with the underlying fatigue processes and represent the actual fatigue state. In selected experiments the influence of elevated temperatures on the cyclic deformation behaviour was investigated. Using the plastic strain amplitude and the change of the specimen temperature with the physically based lifetime calculation “PHYBAL” an excellent accordance with experimentally determined lifetimes could be realised. Microstructural changes were evaluated by transmission electron microscopy in defined fatigue states, additionally, the fracture surface was analysed by scanning electron microscopy.