Structural adaptivity in frontal collisions: implications on crash pulse characteristics

Abstract

Today's passenger cars protect occupants better than ever against most injury types in passenger car frontal collisions. There is, however, one notable exception: neck injuries. Studies have shown that high mean vehicle deceleration is likely to lead to a greater risk of sustaining neck injuries. In order to design future cars that minimize occupant injury risk, it is suggested that the response of the front structure should be adapted to impact severity. A finite element model was used to predict the implications on acceleration time history by yield-strength variation of the longitudinal rails. Results indicate that lower mean deceleration can be attained by lower-yield-stress material, but caution must be taken to avoid stiff engine- firewall contact as this can create high mean decelerations. Furthermore, results indicate that for an adaptable frontal structure to reduce mean acceleration and neck-injury risk, global load paths must be controlled in frontal impacts.