Research On Development And Injury Mechanism Of A Detailed FE Model Based On Occupant Damage Analysis

Brain injury is the leading cause of morbidity and mortality in road accidents, and brings alot of social and economic problems. According to statistics, about3,000people die in trafficaccidents every day, and spend a lot of treatment costs. In recent years, with the rapiddevelopment of the domestic economy, traffic fatalities have ranked first in the world. In2010, the number of deaths caused by traffic accidents was up to65,225, which resulted inthe direct economic losses of90billion yuan. Although safety systems such as airbag, seatbelts are widely applied in vehicles to protect occupants, severe traumatic brain injuries (TBI)still exist in vehicle crashes. Traumatic brain injury could cause more harms to human healthand a burden to a family, even brought caused a great loss to the society and economy. Thus,head injury has become a serious problem. There are many forms of fractures and braininjuries in real traffic accidents, however, it is so difficult to research and observe braininjury with crash dummies. Therefore, it is very important to carry collision biomechanicsfor traumatic brain injury study, which also provides a theoretical support to the optimizationof safety system.In this paper, two two-dimensional head finite element models with and without gyri andsulci have been developed using adult male head CT and MRI scan data, and materialproperties were assigned to both models. The models include brain, cerebellum, corpuscallosum, brainstem, cerebrospinal fluid and skull structures, and separate between whitematter and gray matter. The results show little effect of gyri and sulci on the brain relativedisplacement. However, two-dimensional model owns high material parameters, in order tobetter illustrate the influence of gyri and sulci on the brain response, two two-dimensionalhead finite element slice models with and without gyri and sulci have been developed basedon the two-dimensional models. According to simulation comparison studies, the resultsshow that there is no evident difference in terms of intracranial pressure between the models with and without gyri and sulci under simulated conditions. However, stress and straindistributions were changed due to the existence of gyri and sulci, which suggests thenecessity to include gyri and sulci in the finite element head modeling.Based on the same head CT and MRI scan data, a three-dimensional head finite elementmodel have been also developed by extracting geometry, smoothing geometry surface andmeshing. The model includes human head necessary anatomical structures, especially gyriand sulci. The three-dimensional head finite element model contains695,947solid elementsand128,043shell elements with the total mass of about4.6kg. According to the relevantliteratures, material properties are defined.The loading conditions of Nahum’s experiment, Trosseille’s test and Hardy’s brainmotion experiment reported in the literatures were used as input to the finite element model.The results were compared with experimental data.Meanwhile, the model was validatedunder side impact condition comparing to Yoganandan’s experimental data. The results showthat the three-dimensional head finite element model has a good stability and can be used tosimulate the research of brain response.Effects of different drop heights and different types of ground materials on brain responseunder drop impact conditions are compared on the base of intracranial coup and contrecouppressures and maximum von Mises stress. Moreover, comparison of brain response inducedby dropping the head model from height of63cm onto ground as foam between foreheaddrop impact location and temporal lobe drop impact location is made. The simulation resultshave shown that intracranial coup and contrecoup pressures and maximum von Mises stresskeep increasing with the increase in drop height with ground being the same type of material(foam or wood). But with ground material changed from wood to foam, the above values ofbrain response decrease at the same drop impact height. The temporal lobe drop impactexperiences a higher intracranial contrecoup pressure, a higher maximum von Mises stressand a higher maximum principle strain as compared to those induced by forehead dropimpact with the same drop height and ground material.In summary, although the two-dimensional finite element model of the head can be used as a way to study the response of the brain, the higher material parameters leads tolimitations of its application. The slice model in this paper can overcome this problem, and itis possible to better observe partial brain damage. Three-dimensional finite element model ofthe head in the paper includes complex gyri and sulci structure, and reproduces the humanhead structure, which provides a reference to study brain injury.In summary, although a two-dimensional finite element model of the head can be used as away to study the response of the brain, but the higher material parameters lead to thelimitation of its application. In this paper the slicing model overcomes this problem, and it ispossible to better observe local brain injury. Three-dimensional finite element model of thehead include complex brain structure with gyri and sulci, and reproduce the human headstructure, which provides a reference on traumatic brain injury.