HELMET DESIGNS UTILIZING AN OUTER SLIP LAYER
Disclosed herein is a helmet structure for reducing kinetic energy transmission. The helmet receives contact of an object that transfers kinetic energy to a first layer having material that displaces in response to applied shearing force. The helmet uses a second layer having material that displaces in response to applied shearing force and uses a third layer having material that does not displace in response to applied shearing force to transfer kinetic energy laterally with respect to the skull. Helmet layers can have material with different mechanical responses, including elastic or rubbery elastic. The outer slip layer may also contain reinforcement particles such as metal, glass and ceramic. In one embodiment, each layer in the structure has a different shear modulus and each layer has a higher shear modulus than the immediately preceding layer. The shear modulus of each layer is modified by adding rigid reinforcement to the layer.
1 . A structure for deflecting and spreading kinetic energy transmission, the structure comprising:
a first layer that makes contact with a source of kinetic energy, the first layer comprising material that displaces in response to an applied shearing force with a first shear modulus;
a second layer adjacent to and in chemical attachment with the first layer, the second layer comprising material that displaces in response to the applied shearing force with a second shear modulus that is higher than the first shear modulus; and
a third layer adjacent to and in chemical attachment with the second layer, comprising material that does not displace in response to the applied shearing force.
2 . The structure of claim 1 , wherein the source of kinetic energy is an object.
3 . The structure of claim 2 , wherein the first layer is the only layer that makes contact with the object.
4 . The structure of claim 1 , wherein the first layer is a rigid material.
5 . The structure of claim 1 , wherein the second layer is a polymer.
6 . The structure of claim 5 , wherein the polymer is one of rubberized and plasticized.
7 . The structure of claim 1 , wherein the first layer has a different shear modulus than the second layer.
8 . The structure of claim 7 , wherein the second layer has a higher shear modulus than the first layer.
9 . The structure of claim 8 , wherein the shear modulus of the first layer and the second layer is modified by adding rigid reinforcement.
10 . The structure of claim 9 , wherein the rigid reinforcement is at least one of metal, ceramic and glass.
11 . The structure of claim 7 , wherein chemical changes of a material modify the shear modulus of the first layer and the second layer.
12 . The structure of claim 1 , wherein the first layer has a different rigid reinforcement than the second layer.
13 . The structure of claim 12 , wherein the first layer has different chemical changes than the second layer.
14 . The structure of claim 1 , wherein displacement of at least one of the first layer and the second layer causes deformation of the layer material.
15 . The structure of claim 14 , wherein the deformation of the layer material is reversible.
16 . The structure of claim 14 , wherein the deformation of the layer material is irreversible.