Abdominal Impact And Injury Mechanism Analysis Of A Six-Year-Old Occupant Based On Finite Element Methods

Motor vehicle crashes are the leading cause of death and injury for children in our world. The abdomen is the third most commonly injured body region after the head and thorax in young children with the use of a child restraint or belt-positioning boost seat. Children of 4-8 years of age are at the highest risk of abdominal injury among the young age group. They are 24.5 and 2.6 times more likely to sustain an AIS2+ abdominal injury compared with children 0-3 and 9-15 years of age, respectively. Because of this, it is important and necessary to understand the abdominal injury mechanisms and tolerance for the 4-8 year old in child safety protection. Literature review of children’s biomechanical study of abdominal injury has shown that investigations of injury mechanisms and tolerance of children abdomen by cadaveric experiments are difficult, and the extrapolations of testing results to real world injuries are limited by laboratory settings. Therefore, it is desirable to develop a high biofidelity abdominal finite element (FE) model of children that includes detailed internal organs and can simulate the impact and injury of children occupants during vehicle accidents.In this study, a six-year old child occupant abdominal FE model was developed to simulate children abdominal injury in various impact conditions. The geometric data of the model were extracted from medical CT scan images of a living six-year old child*. Since the original geometric data were based on a supine position, they needed to be reconfigured in a seating position to represent a child occupant. To ensure the model can be used in a real world crash simulation, the process of data reconfiguration was done by referring to test procedure specified in FMVSS213, EDE R44 and C-NCAP, as well as current standard of car seat for a six-year old child. The adjusted body angles included angle of the pelvis, angle between the pelvis and the femur, angle between the pelvis and the spine. The changes of these angles were decided based on a smooth and natural anatomical and physiological transition from a standing position to a seating position. The positions of the internal organs were also reconfigured accordingly. Geometric data adjustment was performed by using GeomagicTM software and model mesh generation was using HyperMeshTM software. The six-year old abdominal FE model includes a detailed representation of the liver, spleen, kidneys, spine, stomach, muscles, skin, skeleton, ligaments and major blood vessels. LS-DYNATM software was used for model analysis.Model validations were carried out by comparing simulation results with impact responses in oblique cadaveric abdominal impacts. Model responses were found following the trends of cadaveric impacts, indicating that this model can be used to simulate children abdominal impact injury. Simulation results also indicated that the ultimate compressive strain can be proposed as an injury criterion for solid abdominal organs.This study provides a baseline understanding of children abdominal injury patterns, which can be served as a foundation for further biomechanical research for injury mechanisms of children abdominal impacts. In the long term, this six-year old finite element abdominal model can be used for accident reconstruction and to optimize designs for child restraint systems in vehicle development.