Frequency spectrum of the human head–neck to mechanical vibrations

Abstract

This study is based on a real finite element human head-neck model and concentrates on its numerical vibration characteristic. Frequency spectrum and mode shapes of the finite element model of human head-neck under mechanical vibration have been calculated. These vibration characteristics are in good agreement with the previous studies. The simulated fundamental frequency of 35.25 Hz is fairly similar to the published documents, and rarely reported modal responses such as "mastication" and flipping of nasal lateral cartilages modes, however, are introduced by our threedimensional modal analysis. These additional modes may be of interest to surgeons or clinicians who are specialized in temporomandibular or rhinoplasty joint disorder. Modal validation in terms of modal shapes proposes a necessity for elaborate modeling to identify each individual part's extra frequencies. Furthermore, it also studies the influence of damping on resonant frequencies and biomechanical responses. It is discovered that damping has an inverse proportionality between damping effect on natural frequency and that on biomechanical responses.

Characteristics of head frequency response in blunt impacts: a biomechanical modeling study

“…In this study, the wavelet packet processing program was employed for investigating the characteristics of head frequency response under blunt impacts. The analysis results (Figure 3) indicate that the impact energy observed on the head is mainly in the frequency bands 0-500 Hz; for few cases with a low impact speed (2 m/s) or a softer block (rubber), high head energy can be seen around the head fundamental frequency (14-35 Hz) reported in the literature (El Baroudi et al, 2012a;El Baroudi et al, 2012b;El Baroudi and Razafimahery, 2014;Fonville et al, 2022;Ghodrati Amiri and Asadi, 2009;Laksari et al, 2015;Laksari et al, 2018;Yang et al, 2017); however, for most cases, the head energy is concentrated in the frequency regions much higher than the fundamental frequency of the head. This finding might suggest that resonance issues could not be considered in the head blunt impacts.…”

“…Gabler et al established a single-degree-of-freedom mechanical model to represent the brain–skull system and found that the intrinsic frequency of the brain was 22.3 Hz–27.5 Hz, which was close to the pulse duration (36 ms–45 ms) of the brain resonance period, and the shape of the brain displacement depends on the magnitude of velocity and acceleration ( Ghodrati Amiri and Asadi, 2009 ). Yang et al (2017) found that the fundamental frequency of the head finite element model was approximately 35.25 Hz for different damping factors. Laksari et al (2018) reconstructed a mild traumatic brain injury case caused by collisions in American football players through dynamic mode decomposition (DMD) and finite element analysis, obtaining a fundamental frequency of 28 Hz ( Laksari et al, 2018 ).…”

Magnetic resonance elastography with guided pressure waves

“…Here, the displacement field maps sustain generation of shear waves over the entire brain with sufficient amplitudes to correctly compute shear storage and loss modulus maps even deep inside—between the cerebellum and the ventricles—at frequencies up to 174 Hz, whereas brain MRE has been limited so far to 100 Hz 14,16,18,30 . Following the frequency spectrum and mode shapes of a human head–neck model, induced higher frequency pressure waves achieved here at 200 Hz and 235 Hz are expected to feed higher compressional modes that do not encompass the whole brain anymore but start to be localized with favored lateral flexion of the nasal lateral cartilage and lateral motion of the mandible 46 . With building brain mechanical atlases in mind, whole‐brain studies with high spatial resolution should be performed at high excitation frequency.…”

“…14,16,18,30 Following the frequency spectrum and mode shapes of a human head-neck model, induced higher frequency pressure waves achieved here at 200 Hz and 235 Hz are expected to feed higher compressional modes that do not encompass the whole brain anymore but start to be localized with favored lateral flexion of the nasal lateral cartilage and lateral motion of the mandible. 46 With building brain mechanical atlases in mind, whole-brain studies with high spatial resolution should be performed at high excitation frequency.…”

Gradient-Induced Mechanical Vibration of Neural Interfaces During MRI

“…In contrast, induced torque based on gradient switching must be considered a dynamic process, because MR imaging is based on rapid and recurring pulses of gradient switching covering a bandwidth up to the double-digit kHz range [10]. Unfortunately, this range overlaps exactly with the mechanical resonance range of implanted structures and the skull [11]. Consequentially, we have to assume that there is a certain risk to excite vibrations on resonance which leads to large amplitudes.…”