Healing of cracks in plates by strong electromagnetic field

The problem of a pulsed high-energy electromagnetic field action on an edge crack in a thin plate, reproducing the pioneering experiment of Soviet scientists on the destruction of the crack tip by a strong electromagnetic field, is considered. The numerical simulation is based on the proposed electrothermomechanical model of a short-pulse high-energy electromagnetic field (HEMF) action on a material with a crack. The model takes the phase transformations (melting and evaporation) of the material occurring in the vicinity of defects and the corresponding changes in the rheology of the material in the areas of these transformations into account, as well as the possibility of electric current flowing between the free surfaces of the crack (breakdown due to electron emission). All physical and mechanical properties of the material are considered temperature-dependent. The model equations are coupled and solved together on a moving finite element grid using the arbitrary Euler–Lagrangian method. The processes of localization of the current density and temperature fields, phase transformations (melting and evaporation) at the crack tip, autoelectronic and thermoelectronic emissions between free crack surfaces, and the effect of these processes on crack healing are investigated. The simulation results are compared with the available experimental data on the pulse field action on the edge crack in the plate. The average metal heating rate, temperature gradients and time forming of the crater obtained in the vicinity of the crack tip are in good quantitative agreement with the experimental data. Away from the crack, as well as on the crack sides away from the tip, the temperature rises slightly. The process of modeling the electromagnetic field action, similar to the experiment, was accompanied by melting at the crack tip, as well as metal evaporation. Thus, under the considered current action, a crater is formed at the crack tip, which prevents the further spread of the crack, leading to its healing. It was not possible to obtain similar results using the previously proposed models.