The performance of high density polyethylene foam in a series of impacts is evaluated. High compressive strains in the range 80–90% cause some permanent buckling of cell walls, but the majority of the deformation recovers within a 24 hour period. A criterion for the performance of the foam in protective helmets is proposed. After one severe impact the performance deteriorates by 30%, but this is much better than for polystyrene foam.
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References
1.
GaleA. and MillsN.J.‘Effect of polystyrene foam liner density on motorcycle helmet shock absorption’, Plat. Rubber. Proc. and Applic. (1985) 5, 101–8.
2.
MillsN.J.‘Back and body protectors for riding’, Equestrian Trade News, Nov. 1985, 21–2.
3.
BenningC.J.‘Plastics Foams’ Vol. 1, p. 315, Wiley Interscience, N.Y., 1969.
4.
British Standards Institution, BS 6658: 1985, ‘Protective Helmets for Vehicle Users’.
5.
MillsN.J., and WhitlockM.D.‘The performance of horse riding helmets in frontal and side impacts’. Injury (1989) 20 to appear.
6.
Gurdjian. ‘Prevention and mitigation of head injury from antiquity to present’. J. Trauma, (1973) 13931–45.
7.
GibsonL.J. and AshbyM.F.‘Cellular Solids’, Pergamon Press, Oxford, 1988, p. 177.
8.
BenningC.J.‘Plastic Foams’ Vol. 2, p. 99, Wiley Interscience, N.Y.1969.
