Professor Stefan Hiermaier, Fraunhofer Institut fur Kurzzeitdynamik

Material Dynamics - Ongoing Research on Strain Rate Dependencies and Shock Wave Effects
When May 18, 2015
from 02:00 PM to 03:00 PM
Contact Name
Contact Phone 01865-273925
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Thermo-mechanical behavior of materials under dynamic loading conditions can be separated into two distinct regimes. One is the strain-rate dependent deviatoric relation between stresses and strains. We observe various changes in the elastic, plastic and failure characteristics at elevated and high strain-rates. While the physical nature is related to inertia effects located on the micro- and meso-scopic level, the standard mathematical descriptions are formulated as phenomenological relations with the strain-rate as independent term. The second regime is governed by the initiation and propagation of so-called shock waves. Here, we typically observe waves with unusual steep wave fronts propagating through media leading to high particle velocities and elevated temperatures. Responsible for the formation and stable propagation of shock waves in specific medium is a convex nature of its Equation of State. In order to numerically model and predict shock wave effects this non-linear relation between pressure, volume and energy needs to be reflected in the hydrostatic part of the stress tensor, e.g. explicitly using a non-linear Equation of State. The seminar will be focused on the shock wave component of dynamic material behavior. Integrated experimental-numerical approaches to investigate high-speed dynamics in materials are demonstrated.