In a large number of industrial applications, piping is used in which flammable gases are transported or can be generated. For the safety assessment of accident scenarios resulting from combustion of such gases with the transition from deflagration to detonation, the precise knowledge of the diverse and complex load values and their interaction with the structure is of central importance. In addition, knowledge of the structural behaviour and fracture mechanisms under the occurring loading conditions that occur plays a fundamental role.
In earlier work of the author, detonation tests were carried out in order to study the combustion processes of oxyhydrogen in austenitic pipes. Depending on the ratio of stoichiometric oxyhydrogen to an inert gas component and pipe wall thickness, multiple adiabatic shear bands occurred in the pipe structure. Adiabatic shear bands are very narrow zones with intense localised shear deformations due to the conversion of a significant portion of strain energy into heat.
To reflect these phenomena numerically, it is necessary to describe material damage as a function of stress triaxiality, Lode angle, strain rate and temperature. In addition, anisotropy has to be considered. A corresponding damage model has to be implemented and the material parameter are to be determined experimentally. The corresponding experimental program consist of different specimen types, including butterfly-specimens in order to cover a wide range of stress states at different strain rates.