Volume 6, Issue 4 (April 2009)
Impact Attenuation Characteristics of Thin Walled Collapsible Air Chambers for Use in Protective Helmets
For the past 40 years, helmets have primarily used expanded polystyrene, vinyl nitrile, and expanded polypropylene foams for impact attenuation. Even though the packaging industry has investigated a variety of structures for impact management, the helmet industry has been slow to adopt these types of innovations. More recently, engineered structures have been developed and introduced for use in the helmet industry. This study was intended to describe the impact characteristics of a thin walled collapsible air chambers designed to be used in sport helmets. This study investigated three structures: rigid walls, a chamber with rigid walls and a vent, and a chamber with rigid walls and no vent. Each structure was impacted with a 5 kg weight at three velocities: 1.9, 2.8, and 3.4 m/s. The three structures were also made using two materials of different stiffnesses. Analysis of the results revealed that the effect of the walls, vent, and material stiffness interacted to produce effective energy management. The results demonstrated that by changing the material stiffness, wall thickness, and vent diameter the performance of the chambers can be engineered to effectively manage different levels of energy.