Abstract: A helmet is formed with a rigid outer shell and three energy-absorbing layers made of two types of CONFOR™ ergonomic, open-celled polyurethane foams. The first layer adjacent the rigid outer shell is a CONFOR™ CF-40 yellow foam and the middle layer is a CF-47 green foam, which is of greater stiffness than the outer layer. The inner-most layer is also a CF-40 yellow foam and, therefore, identical to the outer energy-absorbing layer. The three layers are 0.5″ thick. The helmet body is secured to a user's head with straps, affording a helmet design capable of continuously absorbing energy from multiple impacts while retaining the property of returning completely to its original shape. The multiple layering of materials having different stiffnesses results in the reflection of propagating stress waves through the materials, ultimately absorbing larger amounts of energy than the same materials not layered with alternating stiffnesses could absorb.
Type:
Grant
Filed:
July 30, 1998
Date of Patent:
July 30, 2002
Assignee:
Cerebrix
Inventors:
James Scott Ewing, Maria Maroulis, Andrew F. Conn