Cracking behavior of tungsten armor under ELM-like thermal shock loads: A computational study

• The mechanism of brittle cracking on tungsten surface under transient thermal shock loads was investigated numerically.
• Representative cracking patterns under ELM-like loads are reproduced by extended finite element method simulations.
• Cracking occurrence is predicted by calculating J-integrals of precracks as a function of power density and base temperature.
• The predicted thresholds of power density and base temperature for cracking agree well with the experimental observations.

In this work, the cracking behavior of tungsten under edge-localized mode (ELM)-like thermal shock loads was investigated on the basis of a rigorous computational fracture mechanical analysis combined with the finite element method. Typical transient thermal shock loads of ELM conditions were considered with a relevant range of power density and base temperature for a loading duration of 1 ms. Crack initiation and progressive growth were predicted using the extended finite element method and the J-integral was calculated for the assumed precrack by means of the virtual crack extension method. For a power density of 1 GW/m2 and higher, a crack is preferably initiated near the edge of the loading area and is then followed by a gradual horizontal kinking, parallel to the loading surface. The crack formation is predicted for the power density of 0.6 GW/m2 and above, and when the base temperature is higher than 600 °C, almost no cracks is predicted. The numerically predicted cracking behavior agrees in general with the experimental observations.