Chapter 14 - Resonant frequencies of a human brain, skull, and head

Abstract

In this chapter, we conduct a mechanical modal analysis to determine the first three fundamental frequencies and associated mode shapes of a high-fidelity mesh of the human head and brain of one of the authors (M.F.H.). Since no experimental modal analysis can be conducted in vivo, we employ a quasi-static finite element (FE) method (Simulia/ABAQUS) using the Lanczos eigensolver. The human head (including the neck) mesh was created using Simpleware ScanIP software containing 1248,397 elements with the total volume being 4923.62 cm3 as the brain was 1189 cm3. The FE analysis revealed that the first fundamental frequency for the whole head and the confined brain in the head was 22.3 Hz and 13.9 Hz, respectively. The second resonant frequency for the whole head and brain were 23.8 Hz and 14.2 Hz, respectively. The third resonant frequencies for the whole head and brain were 24.0 Hz and 14.3 Hz, respectively. Finally, the first three fundamental modes were in torsion. The relevance of these mechanical resonant frequencies is that when one wants to design a helmet, they will need to stay away from these frequencies in their design. Furthermore, if a mechanical impact strikes at one of these frequencies, a more deleterious response can arise because of the larger displacements induced to the resonating brain.