FE-Modelling and Material Characterization of Ice-Hockey Helmet

Abstract: The aim of this research was to produce a reliable finite element model of a helmet, that could be used to simulate approval tests as well as impacts to investigate the safety offered. A 2D and 3D mesh was generated from the CAD file of an Easton Synergy 380 with HyperWorks, and then checked referring to standard parameter values. A few specimens cut from the liner were tested with the Instron Electropuls E3000 (Instron, High Wycombe, Great Britain) machine to determine Young’s modulus, Poisson’s ratio and the density of the EPP. The numerical model was characterised with appropriate materials with Ls-PrePost, such as ABS for the shell, EPP for the liner and steel for the impact anvil. The foam was implemented both with the '063_CRUSHABLE_FOAM and the '126_MODIFIED_HONEYCOMB card, in two different configurations. The helmet model was coupled with a finite element model of a HIII head form and three impact scenarios were set up. Backward, lateral and pitched impact were simulated and results were compared with those obtained from the experimental tests carried on at the MIPS. The two configurations were tested in all the three scenarios. The correlation between numerical and experimental results was evaluated by analysing the linear and rotational acceleration, and the rotational velocity, recorded by the accelerometer positioned inside the HIII headform. The parameters used were the Pearson correlation coefficient, the peak linear acceleration score, the shape of the curves, the time occurrence of peaks and the percentage of the difference between them. The first configuration showed good correlation scores (>85%) for the backward and lateral impact, for the rotational velocity and acceleration, while lower values were recorded for the pitched impact simulation. Lower values (70.88% and 77.76%) were obtained for the peak linear acceleration score, which stress the need for modifications of the contact definition in Ls-PrePost or a more detailed material testing. Worse results were recorded for the second configuration, but the smaller computational time required suggests that more attempts should be done in this direction.