Design, optimisation and analysis of a helmet made with graded honeycomb structure under impact load

Abstract

Due to increased attention to safety requirements, energy absorbents such as honeycomb structures have gained increased importance. This study proposes a design for a graded honeycomb structure to use as energy absorbent in helmets in order to reduce impact load during traffic accidents. The honeycomb structure was designed with thickness of 5.9 mm form polypropylene and is covered with a ABS layer. European and UK standards were used for impact test of helmets. Impact test simulation was carried out in ABAQUS software. In order to evaluate the simulation method, numerical results were compared with experimental ones. Based on the results of tests using both standards, designed structure can absorb the applied kinetic energy. Also the measured reaction force, acceleration and HIC are lower than standard thresholds. The behaviour of the proposed honeycomb structure was also compared with a helmet which was made of EPS foam. The impact absorbent structure of helmets was optimised using genetic algorithm; then graded honeycomb structure was compared with foam and foam-filled structures. Based on the results of simulation, honeycomb structure absorbs energy for a longer duration and transfers impact force to the user with lower acceleration compared to EPS.