1. Rationale
The current test procedure allows for the test headform reference plane to be rotated beyond 90 degrees relative to the test anvil surface (i.e. the angle bounded by the reference plane and the flat anvil may be greater than 90 degrees) for certain impact locations (e.g. side impact). Due to the lack of a jaw and chin structure and the physical tapering of the ISO half headform in this lower edge region (i.e., below the basic plane), a wedging or pinching effect occurs to the helmet shell and expanded polystyrene liner during flat anvil impact testing in this region. This results in side impact flat anvil test configurations that are not realistic relative to the human body. If such a head orientation and targeted impact were to occur during a flat (e.g. ground) impact (i.e. extreme lateral flexion), the helmet impact would be preceded by jaw and cheek impact and possibly even shoulder impact. Consequently all the impact forces would not be applied to the lower edge of the helmet but rather they would be shared by the helmet liner as well as other anatomical structures of the body. It should be noted that several manufacturers are reporting test failures of ASTM F1163-04a helmets that have been previously certified by SEI. The manufacturers have confirmed that there have been no design changes and in some cases these helmet models have been in production for over 10 years. Furthermore, these helmets have been well received by the equestrian community and found to be effective at reducing the severity and frequency of head injuries for many years. Side flat anvil impact test failures such as those seen in the laboratory have not been found to occur in real world accidents. It was never the intent of ASTM F1163-04a to induce this type of laboratory test failure as a result of an inadequate description of the impact test procedures.
Keywords
equestrian; horseback riding; horse driving; protective headgear; Equestrian headgear; Horse sports--specifications; Jockey helmets; Protective headgear--specifications; Sports equipment; Sports equipment--specifications;
Citing ASTM Standards
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