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.