Experimental investigation of low-velocity impact on double-walled poloidal segment in nuclear fusion vacuum vessel

The vacuum vessel in nuclear fusion reactor is welded from four poloidal segments, and a comprehensive understanding of impact response of the double-walled characteristic is crucial to cope with active or passive impact events for long-term integrity and safety. A scaled-down poloidal segment prototype model was fabricated, and low-velocity impact experiments were performed under various distinct energy levels using the drop weight impact method. The impact response was comprehensively evaluated in terms of contact force, displacement, stress distribution, and energy absorption characteristics. The effects of punch shape, punch mass, and impact position on dynamic response characteristics were analyzed. The results indicate that there is a positive correlation between impact contact force, displacement, and energy absorption with the energy level. As the punch energy increases from 60 J to 195 J, the peak contact force rises from 38.58 kN to 52.43 kN, and the residual deformation increases from 1.25 mm to 3.40 mm. These investigations are instrumental in assessing the impact resistance and structural integrity of vacuum vessel.