## 3 Results
### Comparison of Head Kinematics and Injuries  
Subsequently, the validated FE models were utilized to assess the protective properties of the four EAFs in a representative pedestrian fall accident scenario. The head kinematics-time curves, encompassing resultant linear acceleration/velocity and resultant angular acceleration/velocity, are presented in Figure 6. Generally, the concrete ground with the regular plastic carpet produced the highest peak linear acceleration (G-max), while the SmartCells produced the lowest. The same trend was observed for the peak angular acceleration (PAA). SmartCells with the highest reduction in G-max and PAA results in  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Corridor** & **Shape** & **Size** & **Phase Shift** & **Overall** \\ \hline Igelkott Floor & 0.977 & 0.996 & 0.883 & 1.0 & 0.979 \\ Kradal & 0.982 & 0.980 & 0.907 & 1.0 & 0.966 \\ SmartCells & 0.976 & 0.985 & 0.994 & 1.0 & 0.993 \\ OmniSports & 0.937 & 0.964 & 0.814 & 1.0 & 0.936 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Results of average CORA rating for four types of EAFs.  
Figure 5: The acceleration–time curves for HIII drop tests and hemispheric drop tests, with related overall CORA score, (**a**) Igelkott Floor HIII 60 cm; (**b**) Kradal HIII 60 cm; (**c**) SmartCells HIII 60 cm; (**d**) Igelkott Floor HIII 100 cm; (**e**) SmartCells HIII 100 cm; (**f**) Kradal hemispheric 60 cm; (**g**) OmniSports hemispheric 60 cm.  
the highest peak angular velocity (PAV), while the Igelkott Floor has the smallest PAV with the second largest reduction in G-max and PAA. The two thinnest EAs, Kradal and OmniSports, produced similar kinematics, but the time for peak value had a small deviation of around 2 ms.  
Figure 7 illustrates a comparison between the von Mises stress (VMS) of the cortical skull (Figure 7a), the 1 st principal strain of the brain tissue (Figure 7c), and the CT scan of the fall accident case (Figure 7d). The most critical situation was observed in terms of VMS on the skull and MPS in the brain tissue when the head impacted against the concrete, as depicted by the extensive red areas. Regarding the VMS on the cortical skull, the SmartCells presented the lightest and smallest areas of stress, followed by the Igelkott floor. Meanwhile, for the MPS in brain tissue, the Igelkott showed minimal area, followed by OmniSports. Upon comparing the patient's CT medical images, it can be observed that the high MPS region of the brain tissue corresponds to the subdural hematoma region--Figure 7d marked with arrows.  
The HIC and risk of head injuries were calculated and presented in Table 3. In this particular reconstruction case, the EAs effectively reduced the VMS in the skull by varying degrees (41%, 12%, 66%, and 10%), but such a high-velocity head impact results in HIC value all above the threshold of 1000. SmartCells shows the lowest HIC value and VMS and the lowest risk of skull fracture, followed by Igelkott Floor, while OmniSports had the highest among all EAs for these three indicators. Igelkott Floor demonstrates the largest reduction in PAV, MPS, and the risk of concussion, followed by OmniSports. Specifically, all EAs have more than a 90% probability of skull fracture injury except SmartCells and have more than a 65% probability of concus  
Figure 6: The kinematics–time curves of the head CG in fall accident reconstructions case [52] against four types of EAs: (**a**) resultant linear acceleration, (**b**) resultant linear velocity, (**c**) angular acceleration, (**d**) angular velocity.