Strategy to increase the speed of a small car impact to a semi-rigid barrier designed for high impact severity

Abstract

ABSTRACTFor a safety barrier to accommodate both small and large vehicle impacts, it should be designed structurally strong to contain large vehicles and flexible to ensure small vehicles’ occupant safety. A semi-rigid barrier was first designed to resist a high impact severity of 272 kJ (13-ton bus – 90 km/h – 15°) and then was modified to ensure the occupant safety of a small car impact of 0.9 tons – 120 km/h – 20° by performing extensive finite element analyses (FEAs). The vehicle relative velocity–time history gradients should have a bi-linear pattern to meet the occupant safety requirements of a strength-designed semi-rigid barrier, other than geometric considerations used to avoid possible snagging. The lateral velocity gradient should increase steeply at the initial stage of impact and decrease moderately around the time when a flying occupant's head is supposed to hit the imaginary frontal or side wall (time of theoretical head impact velocity). The final design was verified through full-scale vehicle crash tests. Furthermore, FEA and a full-scale vehicle crash test revealed that the designed semi-rigid barrier should ensure the occupant's safety at a 0.9 tons – 130 km/h – 20° impact.