A Study Of Collision Response And Injury Mechanism Of Lower Extremity Of 6-Year-Old Child

There is a "cause-and-effect" relationship between the science of vehicle safety development and human body injury biomechanics. Vehicle safety is one of the most important factors to be considered first in vehicle product development process. The safety performance of a vehicle, not only does it need to meet or exceed the requirements of government vehicle safety regulations, but also need to satisfy costumer’s wants and expectations. In recent years, the wide range uses of seat belt and airbag have changed the distribution and spectrum of occupant injuries during vehicle crashes. Head and chest injuries have been better protected, but lower extremity injuries still tended to be increased instead of reduced. Currently, there is a lack of research in lower extremity impact injury for child occupants. Accordingly, based on previous studies, the current research applies finite element method to develop a high biofideltic lower extremity model of a six-year old occupant and uses this model to simulate impact injuries.The geometric data of the model was based a standing position. These data were reconfigured to a seating position by referring to the test procedures specified in FMVSS213, ECE R44 and C-NCAP, as well as current standard of car seat for a six-year old child. The adjusted angles were ensured to follow the anatomical and physiological changes of a six-year old from a standing to a seating position. Muscles and ligaments interfering due to the configuration changes were also readjusted. Finite element meshes were created from the reconfigured geometric data. The model included long bones, knee joint, muscles, ligaments and skin. It possesses high biofideltic geometry and can be used to study injury mechanisms of lower extremity of a six-year child during vehicle crashes.The model was used to study injury mechanisms under various lower extremity impact conditions of the six-year old. There are some differences of the long bones and the knee joints between an adult and a six-year old because the six-year old is not yet completely ossified. Different material properties were assigned to the patella and ligaments surrounding the knee to reflect these differences. The effects due to these differences on impact injury responses were studied. The model was also used to simulate the influences on injury response when the six-year old sitting in the front seat and rear seat. Simulation results showed that injury risk was higher when the child is sitting in the front seat.The lower extremity model developed in this study provides a new tool for further investigation of injury mechanisms for a six-year child occupant. It could help to design better countermeasures to protect the lower extremity of a six-year from crash injury.