## 3 Results
### Von Mises Stress  
Von Mises stress, calculated from principal stresses, is a scalar indicator used in material failure analysis to determine whether a material is at the critical point of yielding or failure [29]. When the stress on the vascular wall exceeds its mechanical failure strength, the aortic intima may tear [30]. Research shows that evaluating vascular wall failure using von Mises stress is crucial for assessing AD [31,32]. Figure 10 labels the two surfaces of the intimal flap in the TL and FL. Figure 12c shows the average von Mises stress changes on the inner surfaces of the TL and FL over a cardiac cycle. Under the same bp, the average von Mises stress fluctuates with bp changes, and the stress trends on both surfaces are the same, with the FL's stress being significantly higher. Under different bps, the average von Mises stress changes significantly, with both surfaces reaching maximum values near 0.113 s, indicating that the intimal flap experiences the greatest concentrated stress at this point. As bp rises, the average von Mises stress at corresponding times increases. Table 4 shows the maximum von Mises stress under three bps, all occurring on the FL's surface, with values of 12,662.0 Pa, 8451.4 Pa, and 5551.9 Pa. Compared to normal bp, the average von Mises stress on the intimal flap increases by 49.82% under hypertension. Figure 11: (**a**) Wall pressure stress distribution contour map at systolic peak (**left**) and mid-diastole (**right**). (**b**) The average pressure of true and FL of intimal flap. (**c**) The average pressure difference between the true and FL of the intimal flap. Based on the overall average von Mises stress of the intimal flap, local simulations were conducted on both the proximal and distal, yielding consistent results. Here, the proximal end is used as an example for analysis. Figure 12a,b illustrate the von Mises stress distribution at the proximal end during systolic peak (left) and mid-diastole (right) for the proximal node and distal node. Figure 12d presents the von Mises stress variation curve over a cardiac cycle on the proximal tear. Since the model's inlet is at the proximal end, the stress variation is influenced by blood flow direction and sudden changes. However, the overall trend aligns with the global curve \begin{table}
\begin{tabular}{c c c c c} \hline
**Blood** & **Lumen** &
\begin{tabular}{c} **Mean \(\pm\) Standard** \\ **Deviation/Pa** \\ \end{tabular} & **Min/Pa** & **Max/Pa** \\ \hline \multirow{2}{*}{High} & True & 5747.6 \(\pm\) 1020.5 & 4329.2 & 9207.0 \\  & False & 8138.4 \(\pm\) 1545.8 & 5983.3 & 12,662.0 \\ \multirow{2}{*}{Normal} & True & 4343.5 \(\pm\) 521.9 & 3366.9 & 5862.5 \\  & False & 6181.8 \(\pm\) 909.9 & 4653.3 & 8451.4 \\ \multirow{2}{*}{Heart failure} & True & 3067.5 \(\pm\) 307.5 & 2404.2 & 3709.6 \\  & False & 4368.7 \(\pm\) 566.9 & 3322.9 & 5551.9 \\ \hline \end{tabular}
\end{table} 
Table 4: The mean and maximum values of von Mises stress of the intimal flap. Figure 12: (**a,b**) [PERSON] stress cloud diagram at the proximal and distal tear between the blood vessel and the intimal flap at systolic peak (**left**) and mid-diastole (**right**). (**c**) The mean von Mises stress curve of the intimal flap. (**d,e**) The von Mises stress curves at the proximal and distal boundaries of the blood vessel and the intimal flap. in Figure 12c, with only slight differences in the distribution of maximum values, which does not affect the analytical conclusions. Under the three bp conditions, the maximum von Mises stress in the FL was measured at 25,445 Pa, 19,466 Pa, and 13,747 Pa, while in the TL, it was 18,097 Pa, 14,057 Pa, and 9983 Pa. Compared to normal bp, hypertension results in a 30.72% increase in the maximum von Mises stress on the intimal flap. Figure 12b,e display the data and special moment maps for the distal observation point. The von Mises stress at the FL-intimal flap junction is generally higher than that at the TL-intimal flap junction.