# A Review of Validation Methods for the Intracranial Response of FEHM to Blunt Impacts
## 2 Experimental Procedures Used in FEHM Validation
### Cadaver Experimentation
#### 2.1.2 Relative Brain Displacement Response
\begin{tabular}{c c c c c c c c c} \hline \hline  & & & & & & & & & \\ \hline  & & & & & & & & & \\ \hline C731 & T2 & Oa & & & & & & & \\  & T3 & Oa & & & & & & \\ C755 & T2 & Oa & & & & & & \\  & T3 & Oa & & & & & & \\  & T4 & Oa & & & & & & \\  & T5 & Fa & & & & & & \\ C383 & T1 & Fd & & & & & & \\  & T2 & Fd & & & & & & \\  & T3 & Fd & & & & & & \\  & T4 & Od & & & & & & \\  & T4 & Od & & & & & & \\ \hline  & & & & & & & & \\ \hline C288 & T1 & Od\({}^{\circ}\) & & & & & & & \\  & T2 & Od\({}^{\dagger,\circ}\) & & & & & & \\  & T3 & Od\({}^{\dagger,\circ}\) & & & & & & \\  & T4 & Od\({}^{\dagger,\circ}\) & & & & & & \\  & T5 & Od\({}^{\dagger}\) & & & & & & \\  & T6 & Od & & & & & & \\ C015 & T1 & Od\({}^{\circ}\) & & & & & & \\  & T2 & Od\({}^{\dagger,\circ}\) & & & & & & \\ C064 & T1 & Od\({}^{\circ}\) & & & & & & \\  & T2 & Od\({}^{\dagger,\circ}\) & & & & & & \\  & T3 & Od\({}^{\dagger}\) & & & & & & \\  & T4 & Od & & & & & & \\ C380 & T1 & Td\({}^{\dagger,\circ}\) & & & & & & \\  & T2 & Pd\({}^{\dagger,\circ}\) & & & & & & \\  & T3 & Td\({}^{\diamond}\) & & & & & & \\  & T4 & Td\({}^{\ddagger}\) & & & & & & \\  & T5 & Pd\({}^{\ddagger}\) & & & & & & \\  & T6 & Td & & & & & & \\ C393 & T1 & Td\({}^{\diamond}\) & & & & & & \\  & T2 & Pd\({}^{\dagger,\circ}\) & & & & & & \\  & T3 & Td & & & & & & \\  & T4 & Td\({}^{\ddagger}\) & & & & & & \\  & T4 & Td\({}^{\ddagger}\) & & & & & & \\ \hline \end{tabular}  O, F, T, P Impact location; C occipital, Frontal, Temporal (left side), Parietal (left side); a,d Impact type; acceleration, deceleration; \(\dagger\) Impact is offset from anatomical axes (otherwise, impacts are aligned); \(\diamond\  
A further ten cases (tests C755-T2, -T3, -T5, C383-T1, -T3, -T4 from [PERSON] et al. [35], and tests C288-T1, -T2, -T4 and C064-T2 from [PERSON] et al. [36]) provide enough data to replicate the impacts numerically and analyse the brain motion. For test C288-T4, where NDT motion data are available but kinematics are not, the impact speed is published (3.0 m/s), as are details of the deceleration block the specimen collides with [36]. This additional detail is not available in [PERSON] et al. [35], preventing tests without kinematic data from being replicated (i.e., tests C731-T1, -T2, C755-T4 and C383-T2), regardless of the availability of NDT motion. These cases include five deceleration scenarios to the occipital region, two decelerations to the frontal region and three acceleration cases, two occipital and one frontal. The cases conducted reported in [PERSON] et al. [36] represent unprotected/protected impacts and aligned/offset impact locations in approximately even proportions within the selection. Another six tests have adjusted strain data reported by [PERSON] et al. [45] (tests C241-T5, -T6, C064-T1, C393-T1, -T2 and -T3), despite NDT motion data not being published by [PERSON] et al. [36] for these cases. While only a small number of tests provide information allowing complete brain displacement and strain comparison, combinations of tests can be applied to FEHM and considered independently to build up a more comprehensive validation tool. Biplanar X-ray and radio opaque targets within the brain were also used by [PERSON] et al. [39]. Previously discussed impact generation methods based on impacts introduce a high degree of variability in the kinematic response of the head. [PERSON] et al. [39] instead generated an impulse by fixing the cadaver specimen into a high powered articulation device. This generated an angular velocity impulse following a half sine shape, with a peak velocity of 41.2 rad/s over 42.1 ms, providing a peak rotation acceleration of approximately 4000 rad/s\({}^{2}\). Four repeats of this test were quantitatively compared to their average behaviour using two rating systems and showed excellent correlation with an average normalised root mean squared deviation (NRMSD) of 4.0% and an average CORA ([PERSON] et al. [48]) score of 0.955.