Analysis of head impacts at different helmet locations during a collision with strain gauge signals

Abstract

American football (AF) is characterized as a collision sport and it has been reported that there are a lot of injuries including catastrophic injuries. Many reports state that head injury has occurred in about 10% of the whole, and especially the incidence of a brain concussion is very high. Biomechanics research to analyze a mechanism of the brain concussion by video analysis has been done since the 1960s. Then, several collision experiments to investigate the linear and rotational accelerations acting in the head during a collision in the actual field have been conducted since 2003. However, it is unclear how much the impact force is acting on a head itself by using an acceleration sensor. Thus, we have constructed a digital filter estimating the head action force with a new method using a strain gauge although the digital filter was obtained from only one location of the head. In addition, we should consider the force on an outer shell of the helmet and the force buffered by the inner pads separately because the head action force at the time of collision is attenuated by inner pads inside the helmet. For this reason, when considering the head acting force, it is necessary to consider the force acting on the outer shell of the helmet and the force buffered by the inner pad. The purpose of this study was to verify the measurement method of constructing a digital filter by using strain gauges attached to the front and back surfaces of an acrylic board.