Effect of helmet in preventing human head and brain trauma in traffic accidents

ABSTRACT: To date, there have been number of studies to demonstrate the effectiveness of helmet during head impacts in car or motorcycle accidents, but these studies were focused on frontal impacts to the head only. There is still a need to study more on helmet to make it more effective, especially in lateral impacts. To my knowledge, previous studies did not focus on the effects of helmet during lateral impacts. This study focuses on lateral impacts and how the helmet prevents head injuries during such impacts. In this thesis, 3D models of the human head and helmet were created in order to build a parameterized Finite Element (FE) model of a protected human head. In the FE model, brain is assumed to be hyper-elastic, the helmet is considered as elasto-plastic and the skull is considered as a linear elastic material. Two separate FE analyses were carried out in this study to find out how the helmet prevents lateral impacts to the head. In the first analysis, the head was not protected and it hits the impact object directly. In the second analysis the head model is protected with a one-layered helmet. In each of these simulations normal and Von Mises stresses are calculated and in the end compared with each other in order to understand the influence of helmet in reduction of such stresses on human head. Afterwards the acceleration of center mass of the head during two simulations are calculated and compared to each other. Helmet reduces head acceleration by 83%, which is a very important cause of Traumatic Brain Injury (TBI). It is clear that the helmet can be very crucial in avoiding brain trauma during car accidents under lateral impacts. ………………………………………………………………………………………………………………………… Through applying more sophisticated modeling in the FEA, the stress distribution at each layer of the helmet and at each part of the head could be illustrated. Therefore, this knowledge will provide insight into designing and developing helmet and safety products to reduce head and brain trauma. Keywords: Traumatic Injury, Helmet, Lateral Impacts, Head, Biomechanics.