Abstract

Regardless of efforts in improving helmet technologies, sport related concussions continue to be a problem. In an effort for advancing helmet liners, this research investigated a design comprised of interconnected fluid-filled cell structures that consist of a primary cell connecting to one or more secondary cells through a channel. When the primary cell undergoes impact, it deforms and pushes the fluid from the primary to secondary cells, which expand accordingly. This fluid motion absorbs the impact and dissipates energy, thereby reducing the force and acceleration transfer to a contacting body. Structures made with two hyper elastic polymers, silicone and polyurethane, were investigated in simulation and experimentation. For both materials, increasing the number of secondary cells in the structure will decrease the amount of force transfer and resulting acceleration. The optimized design, with one primary and two secondary cells, showed reduction of force by 25.2% and resulting acceleration of 80.7 m/s2 when using silicone, while cells made of polyurethane showed a 33.5% reduction of force and resulting acceleration of 72.5 m/s2. In comparison, a commercial liner (Vengeance DCT TPU Lateral Helmet Liner by Schutt® tested using the same test procedures, showed reduction in force by 24.3% and resulting acceleration of 87.0 m/s2.

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