Material property influences on the modelling of child brain injuries

Finite element simulations of a human head are often used to enhance our knowledge of injury mechanisms, assist in injury prediction and to develop preventative devices such as helmets and seatbelts. While many adult models have been developed and validated, few child models have been developed due to a lack of material data and experimental studies of which to validate the model. Therefore, many child head injuries are investigated via dimensionally scaled adult head models without the replacement of the adult material properties by the child material properties. This study aims to evaluate whether applying the child material properties to a dimensionally scaled adult head significantly influences the predicted risk of brain injury of a child head due to impact accidents. The adult model of Horgan & Gilchrist (2003) was scaled to the size of a 6-month old child's head and then this model was compared to the one with child material properties appended. Frontal, lateral and occipital impacts were simulated, and the use of the child material properties was found to decrease the peak von Mises stress in the brain by up to 58.2%. Applying this result to the University Louis Pasteur criterion (Marjoux et al, 2008) yielded a maximum decrease of 90% in the relative risks of severe brain injury. Therefore, when analysing child brain injuries with a scaled adult model, the child material properties should be applied in order to more accurately predict the extent of brain injury. Our further numerical study explored the sensitivity of the skull and brain material properties on head injuries. The results showed that the impact force is mainly affected by the skull material properties and the brain material properties have negligible influence on the impact force. However, the maximum von Mises stress in the brain is mainly affected by the brain material properties.