## 5 Conclusions  
In this study, the damage mechanism of the box structure subjected to the internal blast load is analyzed based on the characteristics of the internal blast loadings and the  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**No. **} & \multirow{2}{*}{**W(g)**} & \multirow{2}{*}{ \begin{tabular}{c} **Explosive** \\ **Type** \\ \end{tabular}  } & \multirow{2}{*}{\( \begin{array}{c} \boldsymbol{a\times b}\\ \textbf{(mm)}\end{array} \)} & \multirow{2}{*}{\( \begin{array}{c} \boldsymbol{H\text{ (mm)}}\end{array} \)} & \multirow{2}{*}{\( \begin{array}{c} \boldsymbol{\sigma\text{ (MPa)}}\end{array} \)} & \multirow{2}{*}{\(\begin{array}{c} \boldsymbol{D_{in}^{*}}\)} & \multirow{2}{*}{\( \begin{array}{c} \boldsymbol{Calculated}\\ \textbf{Result \omega/}\textbf{{\emph{It}}}\end{array} \)} & \multirow{2}{*}{**Experimental**} & \multirow{2}{*}{**Error**} \\ \hline \multirow{8}{*}{\(1\)[6]} & 12.8 & TNT & 300 \(\times\) 300 & 2 & 370 & 0.084 & 7.84 & 7.44 & 0.05 \\  & 23.9 & TNT & 300 \(\times\) 300 & 2 & 370 & 0.158 & 9.66 & 11.95 & \(-\)0.19 \\  & 40.2 & TNT & 300 \(\times\) 300 & 2 & 370 & 0.266 & 13.61 & 17.19 & \(-\)0.20 \\  & 43 & TNT & 450 \(\times\) 450 & 3 & 368 & 0.084 & 7.82 & 7.7 & 0.03 \\  & 84.5 & TNT & 450 \(\times\) 450 & 3 & 368 & 0.166 & 9.83 & 13.13 & \(-\)0.26 \\  & 146 & TNT & 450 \(\times\) 450 & 3 & 368 & 0.290 & 14.74 & 18.5 & \(-\)0.20 \\  & 99 & TNT & 600 \(\times\) 600 & 4 & 360 & 0.082 & 7.73 & 8.23 & \(-\)0.05 \\  & 200.1 & TNT & 600 \(\times\) 600 & 4 & 360 & 0.168 & 9.77 & 13.33 & \(-\)0.26 \\  & 345 & TNT & 600 \(\times\) 600 & 4 & 360 & 0.290 & 14.69 &  
mechanism of the structural response. Different damage modes are classified according to the characteristics, and a dimensionless number and analysis method with clear physical meaning that considers structural deformation, inertia effect, and structural scale effect is proposed. Based on the study of isotropic box structures, a comparative study of damage effects of anisotropic box structures with different structural dimensions is carried out. The influence of the coupling relationship between the structural dimensions and the blast load on the damage modes is analyzed. Three competing mechanisms of material damage are also investigated, and the modes of breakage extension are analyzed and classified. Finally, the validity of the analysis method was verified by analyzing a large number of experiments. The main conclusions are as follows. 1. The damage mechanisms and damage characteristics of the box structures subjected to different TNT-equivalent implosion loads were analyzed. The damage modes are divided into large deflection plastic deformation, central breach, corner or edge tensile tearing, and shear damage. The non-dimensional \(D_{in}^{*}\) for the damage analysis applicable to internal explosions is proposed, and the equations describing the deformation of wall plates are presented. The variation of deflection and the open area with the non-dimensional \(D_{in}^{*}\) for rectangular slabs of different structural dimensions under different implosion loads is further investigated. The variation of deflection and the open area of the wall plates subjected to different implosion loads with the non-dimensional \(D_{in}^{*}\) is further investigated. 2. Based on the study of isotropic box structures, a comparative study of the damage mechanism and damage characteristics of anisotropic box structures is carried out, and the effects of plate size and aspect ratio on the critical value at damage mode transition are analyzed in detail. For the same area of plates subjected to the same internal blast load, the smaller the aspect ratio \(\gamma\) is (closer to a square plate), the larger the central deformation of the plate is. When the deformation exceeds the fracture strain, the damage mode of the wall plates changes from mode I to mode II.