PROTECTION OF THE SIDE OF THE HEAD

The side of the head is a frequent impact site for pedal cyclists, mot orcyclists, and industrial workers. It is vulnerable to impact, yet ma ny helmet standards do not have impact tests at the side of the helmet . Laboratory impact tests should reproduce the phenomena in real impac ts, but usually they do not allow the headform to rotate, or ignore th e effect of the neck on the motion of the head. The authors designed a linkage, simulating the flexibility of the neck, for use with anthrop omorphic dummies in helmet testing. Impacts at the side of the helmet, normal to the helmet surface, were made with flat and hemispherical s trikers. Head rotation during impacts caused the impact site to move, in some cases to below the level protected by the helmet. The peak ang ular head acceleration correlated with the peak linear accelerations. Neck flexibility means that helmets can protect the head from higher k inetic energy impacts than those specified in standards using immovabl e headforms or impact anvils. The load spreading efficiency of polypro pylene foam, used in soft shell bicycle helmets, is better than that o f polystyrene foam. The authors conclude that the side of the head can be protected by a suitable helmet design. Copyright (C) 1996 Elsevier Science Ltd.