IDENTIFICATION OF HEAD INJURY MECHANISMS ASSOCIATED WITH RECONSTRUCTION OF TRAFFIC ACCIDENTS. 1999-13-0002
Head injuries often occur in frontal accidents, which are the most frequent type of vehicle collision and causes of injuries. Impact of the head with the steering wheel has been identified as the major source of lesions. In order to mitigate this contact, vehicles available on the European market are now equipped with airbags in addition to the safety belt. Although the inflation of airbags reduces the severity of head injuries in moderate to severe frontal crashes, lesions due to a contact with the steering wheel are still observed in collisions with a severity under the deployment threshold. The analyses of real-life accidents involving airbag deployments show that additional injuries occur in accidents of relatively slight severity. Accordingly, several authors have proposed to increase the deployment threshold of the airbag system for belted occupants. The absence of head injury representative biomechanical criteria prevents an assessment of the risks induced by such a modification.
Many studies in the past have demonstrated that the current biomechanical criteria (HIC, SI) are meaningless in real accident situations. Despite the fact that the mechanisms causing head injury were unknown, several injury criteria were proposed which were based on hypothetical theories. To obtain a better understanding of head injury mechanisms and propose new biomechanical criteria in the future, a new research methodology has been developed.
The purpose of this study is to present the accident reconstruction methodology so as to provide an estimate of the head loads which are associated with the injuries sustained by the victim. This is however only the preliminary step in the complete analysis. Simulations of head loads with the conditions extracted from the accident reconstruction are the next stage for the identification of head injury mechanisms.