Christian Flack, M.Sc.
Beethovenstraße 51
38106 Braunschweig
Telephone: 0531/391-3665
Research project:
Multifield-modelling for concrete with discrete element methods
The goal of this research project is the development of a discrete element model for concrete which deals with mechanical, chemical, thermal and hygric influences. The theory of porous media is the most common theory for concrete in literature. This model should be understood as an alternative way to describe the heterogenous media.
Because of the wide area of application concrete is exposed to many different loads during lifetime. The characteristics of the concrete structure are changing due to internal and external influences. With a detailed description a significant lifetime prediction of a structure can be done.
The present model for the concrete structure consists of individual particles with different properties. Solid particles are used to describe the solid phase. These particles are bonded together with a spring-damper system. The constants for the spring and the damper are chosen by satisfying the macroscopic behaviour of concrete. The liquid and gaseous phase are described by volume particles. Analogous to the spring-damper system contact models are developed to describe the exchange and transport of matter between the single particles. Additionally some failure criteria can applied to the model. Furthermore chemical reactions on particles can be taken into account. By means of the chemical equation and the reaction rate, which can be established by experiments, the change of mass or density of a particle is considered.
Contact forces are evolving due to contraction or expansion of particles. The evaluation of the internal contact forces leads to the residual stresses of the domain as a result of creep, shrinkage or chemical reactions.
Publications within the framework of the RTG:
Doctoral thesis:
C. Flack. Mehrfeldmodellierung von Beton mit diskreten Element Methoden.
Conference contribution with publication in conference proceedings:
C. Flack and D. Dinkler. Mehrfeldmodellierung von Beton mit der Diskrete Elemente Methode. In: Schneider J., Kiziltoprak N. (eds) Forschungskolloquium 2018 Grasellenbach. Springer Vieweg, Wiesbaden. 2018.
C. Flack and D. Dinkler. Towards multifield discrete element modeling of concrete structures. Proceedings in Applied Mathematics and Mechanics (PAMM). 2019. (accepted)
Conference contribution without publication in conference proceedings:
C. Flack, F. Ockelmann and D. Dinkler. Towards Multifield Discrete Element Modeling Of Concrete Structures. WCCM 2018, New York, USA, 2018.
C. Flack, F. Ockelmann and D. Dinkler. A multifield discrete model for concrete. ECCOMAS MSF 2017, Ljubljana, Slovenia, 2017.
C. Flack, F. Ockelmann and D. Dinkler. A multifield discrete element model for concrete. Particles 2017, Hannover, Germany, 2017.
C. Flack, F. Ockelmann and D. Dinkler. A multifield discrete model for concrete. Coupled Problems 2017, Rhodes, Greece, 2017.
C. Flack, F. Ockelmann and D. Dinkler. Multifield Discrete Element Modelling for Concrete Structures. MUMO 2016, Dubrovnik, Croatia, 2016.