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Abstract
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The significance of the "packaging problem" of man in his multitudinous hazardous pursuits grows increasingly apparent. Even a cursory survey of statistical data related to injury and death reveals the importance of protecting man as a "package" from the environment, his fellows and himself. The ability of the human organism to survive even massive trauma, if the head is protected, has been abundantly demonstrated; thus the foremost problem of packaging to be considered relates to head protection.
Widely diverse groups have become interested in protective headgear in recent years, including occupations and activities ranging from the military aviator through firemen, police and baseball players to the traveling salesman on the highway. Some of the groups have specialized requirements but in common there are certain basic considerations.
In order to set to work intelligently, the designer of a protective package must needs have some knowledge of the types and magnitudes of hazards involved under the conditions of usage. Properly, there must also be some understanding of degree to which the packaged article may safely be subjected to these hazards.
The primary problem in protecting the head against impact is that of minimizing kinetic energy transferred to the head. Since the head mass is finite and limited, the energy of transfer is a function of the ratio of the impacting mass to the head mass, and is generated by the relative change in velocity which occurs between the two. It matters not which of the two masses is actually in motion. As the impact occurs, the relative velocity of one mass to the other is reduced to zero, and at this point, reactive forces existing in any part of the mechanical system which has been deformed are at a maximum. |