Numerical simulations of spalling tests in order to investigate material properties of UHPC

In order to evaluate the material composition of Ultra High Performance Concrete (UHPC), material properties such as dynamic tensile strength or fracture strength and also the fracture energy under impact loading are of significant importance. The use of a modified Hopkinson Bar enables the determination of the required data. On the basis of experimental investigations our contribution deals with the numerical finite element simulation of the Hopkinson Bar test. The propagation of stress waves is reproduced by means of a special time-integration scheme. We simulate the propagation of cracks by using adaptive cohesive elements including a corresponding separation law. The critical energy release rate (Griffith-energy) is calculated and compared to the values determined by experimental results. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)