Sport helmet certification standards solely prescribe the use of vertical drop towers in their protocols; a mechanism which mimics the head impacting the ground. Athletes are more commonly injured via collisions with other players; however, and the current certification standards do not incorporate this mechanism of injury in their test methodologies. At the most basic level, these two injury mechanisms can be differentiated by impact mass. The purpose of this study was to determine the effect of impact mass on the dynamic response of a Hybrid III head form. This was carried out by impacting the front location of the un-helmeted head form over a range of inbound velocities (2.0 m/s, 3.0 m/s and 4.0 m/s) and system compliances (rigid neck, compliant neck and unrestrained head and neck) on two different test systems represented by impact mass (monorail vertical drop tower and horizontal linear impactor) to more completely characterize the relationship. Significant main effects and interactions were observed for impact mass, inbound velocity and system compliance on peak resultant translational acceleration and peak resultant rotational acceleration (p<0.05). Impacts on the monorail vertical drop tower (greater impact mass), resulted in higher acceleration values than the same impacts on the horizontal linear impactor, implying that the monorail generates more severe impacts. The greatest accelerations were also seen at the higher velocities, indicating that athletes impacted at higher velocities are at greater risk of suffering mild traumatic brain injury (mTBI). The relationship was non-linear for system compliance: the least compliant system generated the lowest translational accelerations, followed by the most compliant system, and ending with the intermediate level of system compliance. Rotational acceleration increased with increasing system compliance.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/28886 |
| Date | January 2011 |
| Creators | Coulson, Natalie R |
| Contributors | Hoshizaki, Thomas Blaine, |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 103 p. |
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