Regensburg 2013 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 30: Topical Session: Fundamentals of Fracture - Modelling Intergranular Fracture

MM 30.4: Talk

Wednesday, March 13, 2013, 11:00–11:15, H4

A Finite Element Analysis of the Fracture Behavior of Tungsten at the micro scale — •Christoph Bohnert^1,2, Nicola Julia Schmitt², Sabine Maria Weygand¹, and Oliver Kraft² — ¹Karlsruhe University of Applied Sciences, Department of Mechanical Engineering and Mechatronics, D-76133 Karlsruhe, Germany — ²Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM), D-76344 Eggenstein-Leopoldshafen, Germany

Due to its high melting point tungsten has the potential to be used as a structural material in future energy applications. However, one of the challenges is to deal with the brittleness at room temperature, where the fracture behavior of polycrystalline tungsten is strongly influenced by the grain structure and texture as well as sample dimensions. The aim of the present work is to numerically analyze crack initiation and growth in single crystal tungsten microbeams and to relate it to corresponding experimental observations.

A finite element model was developed to study the fracture behavior of the cantilever at different crack orientations. As plastic deformation is observed at the crack tip, plastic deformation is implemented using a crystal plasticity approach which allows for specifying the crystal orientation. Crack initiation and growth are treated by using the cohesive zone method. Based on experimental oberservations, the material parameters are estimated, and the fracture model has been applied to simulate microbending tests. The simulations allow for comparison of the computed with the measured load displacement curves as well as details of the fracture process, ultimately at various length scales.