In our previous papers, it has been reported that when rings and shells are subjected to an internal uniformly-distributed pressure pulse, dynamic elastic buckling due to the nonlinear coupling between the breathing mode and bending modes may occur and further cause the strain growth phenomenon in explosion containment vessels. In this study, the influence of defect distribution on dynamic buckling of plane-strain rings under internal uniformly-distributed pressure pulse is studied, in which three cases with one defect, six defects and twelve defects are employed in the finite element model. It is found that defects influence the initial buckling response shapes and occurrence of dynamic buckling. However, the excited bending mode is the same for the different defects distribution cases.

Blast-proof unit is designed to alleviate the shock wave transmitting to the other unit, in which the damage of accidental explosion is mainly caused by the transmission wave through the wall and diffraction wave over the upper edge. Investigation on the blast flow field in blast-proof units subjected to internal blast loading is studied by numerical simulation in the current paper. The influence of the height of the proof unit is analyzed and on the cap situation is studied. The result shows that it may not have a positive effect on reducing the diffraction wave by increasing the height of units, because it may enhance the reflection wave, which might have a greater effect than the diffraction wave. We can reduce the shock wave in the next unit by adding a cap, which is very effective. The study may contribute to further understanding on the experiment results and the design of blast-proof units.