Vulnerable Road User head impact evaluation for bus front ends using Finite element model

Abstract

Numerical studies in crashworthiness have played an important role in optimizing vehicle design and making them pedestrian friendly. The developments seen in passenger vehicle exceeds the developments in bus when concerning pedestrian safety. Head injury is one of the most frequently sustained injuries during an impact between a bus and a pedestrian and these typically result in a 20% fatality rate. The impact may produce pure linear acceleration of the head but typically also produce rotation acceleration of the head. The head kinematics are known to highly influence the type of resulting head injuries. In this master’s thesis, head to bus front impacts were simulated and the responses were evaluated to study the effect of head impact location, orientation, and velocity on head kinematics and injury risks. Finite Element (FE) models of a free-motion head form and a Hybrid III 50th percentile male crash test dummy and a of a naked frame of Scania lowentry comfort bus with attached front windscreen and plastic panel were used in this study. The Head Injury Criteria, Rotational Injury Criteria, and the Power Rotational Head Injury Criteria were used to estimate the injury risks. The resulting injury risks based on linear accelerations were similar for the simulated impacts when the human head was represented by the free-motion headform and the human was represented by the Hybrid III model.Since the estimated head injury based on rotational accelerations were rather high the Hybrid III is the recommended tool for bus front head injury risk estimations.