A Numerical Analysis of Pre-Deployment Effect of Side-Impact Airbags in Reducing Occupant Injuries

Abstract

Side impact collisions represent the second greatest cause of fatality in motor vehicle accidents. Side-impact airbags (SABs), though not mandated by NHTSA, have been installed in recent model year vehicle due to its effectiveness in reducing passengers’ injuries and fatality rates. However, the increase in number of frontal and side airbags installed in modern vehicles has concomitantly led to the rise of airbag related injuries. A typical side-impact mechanical or electronic sensor require much higher sensitivity due to the limited crush zones making SABs deployment more lethal to out-of-position passengers and children. Appropriate pre-crash sensing needs to be utilized in order to properly restraint passengers and reduce passengers’ injuries in a vehicle collision. A typical passenger vehicle utilizes sensors to activate airbag deployment when certain crush displacement, velocity and or acceleration threshold are met. In this study, it is assumed that an ideal pre-crash sensing system such as a combination of proximity and velocity and acceleration sensors is used to govern the SAB pre-deployment algorithm. The main focus of this paper is to provide a numerical analysis of the benefit of pre-deploying SAB in lateral crashes in reducing occupant injuries. The effectiveness of SABs at low and high speed side-impact collisions are examined using numerical Anthropomorphic Test Dummy (ATD) model. Finite Element Analysis (FEA) is primarily used to evaluate this concept. Velocities ranging from 33.5mph to 50mph are used in the FEA simulations. The ATD used in this test is the ES-2re 50th percentile side-impact dummy (SID). Crucial injury criteria such as Head Injury Criteria (HIC), Thoracic Trauma Index (TTI), and thorax deflection are computed for the ATD and compared against those from a typical airbag system without pre-crash sensing. It is shown that the pre-deployment of SABs has the potential of reducing airbag parameters such as deployment velocity and rise rate that will directly contribute to reducing airbag related injuries.