Development of Biomechanical Model and FEA Modal Analysis of the Gravid Human Uterus Exposed To Ramp-Induced Vibration

Abstract

Natural frequencies, frequencies at which bodies resonate and consequently fail, are very crucial in studying the dynamics of mechanical and biomechanical components. A number of researchers have carried out several studies on vehicle occupants with regard to various sitting postures, seat types and road roughness levels in which resonant frequencies of certain body parts have been established. In the area of vibration analysis for pregnant occupant, there is practically no significant research to pinpoint the frequencies at which the tummy of the pregnant woman could critically resonate. Therefore, this work is focused on developing a plausible biomechanical model and to determine the natural frequencies of the gravid human uterus. The Kelvin-Voigt’s and Maxwell’s spring-damper models were used to represent the amniotic fluid and ligaments of the uterus respectively. Finite element modal analysis was performed in ANSYS workbench (version 15.0) and the 3-dimensional model realized 300 modes at frequencies below 7.30 Hz. It is found that the gravid human uterus has a first principal resonance of 1.03 Hz and the second and third principal resonance occurred at 2.68 Hz and 3.99 Hz respectively. Interestingly, the foetus has a singleton principal resonance frequency of 1.03 Hz whilst the uterus wall has two principal frequencies of 3.05 Hz and 4.62 Hz. It is recommended that assessment of stresses and deformation on the gravid human uterus under ramp-induced vibration is crucial for future female reproductive health studies.