Investigate the Energy Absorption Capacity of EPS with Different Thicknesses in the Motorcycle Helmet

Abstract

This paper is based on the energy absorption of Expanded polystyrene (EPS) into a motorcycle helmet to evaluate the impact resistance on a flat anvil in the shock absorption test of QCVN:2008. The paper is divided into two sections: In the first section, the EPS liner of either helmet is experimentally determined its density and stress-strain curve used in FEA models. The other is tested shock absorption at SMEQ in order to measure the acceleration value at the peak position, 3 ms and 6 ms of acceleration curve which is required in the standard. In the second section, a basic model with three layers (head form, EPS, and shell) is built in Solidworks and simulated in LS-DYNA under experimental conditions. After compared with experimental values, the model is optimized to obtain an error of less than 5%. In order to investigate the behavior of this model with different thicknesses, the EPS layer thickness of the optimized model is modified from 10 to 20 mm. As a result, the acceleration values depend on the EPS layer thickness, the peak acceleration increase rapidly in proportion to the thickness from 10 to 14 mm and then the acceleration decreases to a limit value of 20 mm thickness. The simulation result also shows that the stress of the ABS shell is concentrated in at the impact point which is the center of the circle and slightly decreases from the center. By using simulation technology in the impact tests, the shock absorption of EPS is controlled by its thickness which is 16 mm or more for better protection.