Abstract: The crashworthiness of vehicle front side-rails was studied and then improved to reduce occupant leg injuries caused by offset impact. The bending crushing and axial crushing were analyzed with various sections in vehicle front side-rails using a finite element method. Improvement in the front side-rail extension,
filled with high-density structural foam, was verified in an offset impact test. The results indicate that the deforming mode of the front side-rail extension is effectively controlled after filling high-density structural foam with the intrusion into the occupant cabin significantly reduced. The average load, total energy absorption, energy absorption per mass, and the axial force transmission capability are increased by nearly two times with improved front side-rail bending compared with ordinary front side-rail bending. The driver lower right leg tibia index is reduced from 0.97 to 0.38 with the driver lower leg tibia load obviously decreasing.Therefore, this design maintains the occupant cabin integrity and enhances the vehicle crashworthiness.

Key words: automotive safety, offset impact, vehicle front side-rail, crashworthiness, occupant cabin, highdensity structural foam