## 3 Results and Discussion
### Crashworthiness Behaviors  
In order to investigate the crashworthiness of the proposed structures, their impact resistance was assessed using a drop impact tester (DIT302A-TS, Shenzhen Wance, Shenzhen, China). The bio-inspired structures were subjected to an impact from a set height with a hammer body of a specific mass and shape. The impact resistance of the samples was then evaluated based on the experimental results obtained after impact, as illustrated in Figure 9. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Type** & **Simulation/Test Values** & \begin{tabular}{c} **Mass** \\ **(g)** \\ \end{tabular} & \
\begin{tabular}{c} **Maximum Bending** \\ **Load (N)** \\ \end{tabular} &
\begin{tabular}{c} **LWN-B** \\ **(N/g)** \\ \end{tabular} \\ \hline BS-1 & Simulation values & 103.42 & 3789.3 & 36.64 \\ BS-2 & Simulation values & 103.42 & 3684.3 & 35.62 \\ BS-3 & Simulation values & 103.42 & 3990.3 & 38.58 \\ BS-4 & Simulation values & 103.42 & 5339.8 & 51.63 \\ BS-5 & Simulation values & 103.42 & 4094.5 & 39.59 \\ BS-6 & Simulation values & 103.42 & 5123.4 & 49.54 \\  & Test sample \#1 & 103.38 & 4769.855 & 46.14 \\  & Test sample \#2 & 103.44 & 4928.842 & 47.65 \\ BS-7 & Test sample \#3 & 103.39 & 4853.417 & 46.94 \\  & Simulation values & 103.45 & 5087 & 49.17 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison between bending data from experiments and simulations. Figure 8: Three-point bending properties of different BSs. (**a**) Comparison between experimental results and simulation for BS-7; (**b**) bending load-displacement simulation curves for different BSs; (**c**) maximum compressive load of BSs; (**d**) bending test. Table 6 lists the results of the impact test. To reduce accidental errors and ensure the accuracy of the test results, three samples were made for each thin tube structure, and the impact test was carried out separately. Table 6 demonstrates that the \(EA\) and \(SEA\) of BS-4, BS-6, and BS-7 are high and similar, which indicates that their energy absorption capacity is strong. The \(EA\) and \(SEA\) values of BS-1 and BS-2 are the lowest, and their energy absorption capacity is poor. The reason for the poor energy absorption capacity of BS-1 and BS-2 is due to their lower \(EA\) and \(SEA\) values, which can be attributed to the structure of the tubes. The tube with a star-shaped outline shaped like a starfish as its main framework  
Figure 10: Force-displacement and energy-displacement curves of each BSs. (**a**) Test fixture; (**b**) BS-1; (c) BS-2; (**d**) BS-3; (**e**) BS-4; (**f**) BS-5; (**g**) BS-6; (**h**) BS-7. structure has a more stable structure because of its high symmetry, which allows for a more uniform distribution of forces inside the entire tube, reducing the risk of local overloading, as well as deformations or failures. On the other hand, the tubes designed with four-sided and hexagonal structures within the five angles based on the star-shaped main framework structure have a relatively unstable structure. This irregular structure makes it prone to generate local overloads when subjected to external forces, thereby increasing the risk of tube deformation or failure. In addition, the _CLE_ value of BS-3 is the highest, which indicates that its load uniformity is good. In turn, BS-3 has low _EA_ and _SEA_ values and poor energy absorption capacity. The _CLE_ values of other BSs are relatively similar. BS-4 has the highest \(P_{\max}\), and BS-2 has the lowest \(P_{\max}\). To further study the crashworthiness characteristics of thin-walled tubes, the data in Table 6 are further processed to obtain Table 7 and Figure 11. Table 7 illustrates that the _EA_ and _SEA_ values of BS-3 are close to those of BS-5. Compared with BS-1, the _EA_ and _SEA_ values of BS-3 are 28.5% and 28.5% higher than that of BS-1, respectively. Compared to BS-2, the _EA_ and _SEA_ values of BS-3 are 29.8% and 29.8% higher than that of BS-2, respectively.