Human Body Model and Passive Safety of Vehicles: Analysis of biomechanical results and study of injuries on abdominal organs

Every day people have a car accident and safety in the car becomes more and more an important requirement. Crash safety tests are still used today to understand how safe the vehicle is for the occupants, and which improvements can be made. Furthermore, they are very expensive and limited in predict injuries, so companies have begun to aim for another approach, the Finite Element Method (FEM). Total Human Model for Safety (THUMS) was introduced in computer analysis of vehicle collision. It is a human body computational model, which allows simulating the behaviour of the human body during impacts, giving a more accurate injuries prediction than rigid dummies tests. THUMS is still an imperfect instrument, the aim of this thesis is trying to make changes to render the model more realistic, basing on human body properties. It is then validated comparing it to cadavers’ behaviour. THUMS investigation presented in this study has focused on thoracic and abdomen organs, especially costal cartilage, thoracic fat, liver, and spleen. Material’s changes, based on literature, were preferred than geometric aspects to improve the model. A better definition of costal cartilage is proposed, an analysis of thoracic fat’s properties is conducted, and the liver and spleen’s materials are completely modified. THUMS is validated after each change. In the validation phase, biomechanical results are analyzed and compared with corridors obtained with cadaver tests to understand if the modifications influence the THUMS’ behaviour.   Once the validation of the modified THUMS is achieved, a real accident is reproduced using the sled mode. The intention is to apply an original energy-based injury criterion, the Peak Virtual Power method (PVP), for the liver and spleen, with which obtain the Abbreviated Injury Scale (AIS) levels using the AIS corridors. Finally, these AIS levels are compared with the real AIS scores, obtained from injuries to the organs of the occupant in the car crash, understanding the accuracy of the PVP method.