Protective helmet for mitigation of linear and rotational acceleration

Abstract

Embodiments provide protective helmets configured to protect the head from linear and rotational acceleration in an impact. In various embodiments, the helmets may include an outer layer, an inner layer, and at least one intermediate layer coupled to the outer and inner layers by alternate fixation sites, thereby providing a suspension between the outer and inner layers. In various embodiments, the intermediate layer may be made from a honeycomb material, such as an aluminum honeycomb. In use, in-plane deformation of the honeycomb may allow for translation of the outer layer in a substantially tangential direction relative to the inner layer, thereby mitigating rotational acceleration imparted by the tangential impact component. Additionally, crumpling of the honeycomb in a substantially non-elastic manner may deplete impact energy to minimize the elastic rebound that can contribute to linear and rotational head acceleration, thereby mitigating linear acceleration imparted by the perpendicular impact component.

What is claimed is:  
     
         1 . A helmet for protecting a head during an impact, comprising:
 an outer layer;   an inner layer; and   at least one deformable intermediate layer, wherein the intermediate layer has substantially no elastic rebound, and wherein the intermediate layer is coupled to both the outer and inner layers at alternate fixation sites.   
     
     
         2 . The helmet of  claim 1 , wherein the intermediate layer is configured to provide a suspension between the outer and inner layers. 
     
     
         3 . The helmet of  claim 1 , wherein the outer layer is configured to translate in a substantially tangential direction relative to the inner layer via in-plane deformation of at least a portion of the intermediate layer. 
     
     
         4 . The helmet of  claim 3 , wherein the intermediate layer is configured to absorb impact energy by deformation in directions both perpendicular and tangential to the outer layer. 
     
     
         5 . The helmet of  claim 3 , wherein the outer layer is further configured to translate in a direction substantially perpendicular to the inner layer. 
     
     
         6 . The helmet of  claim 1 , wherein the helmet further comprises a glidable interface layer disposed between the intermediate layer and the inner and/or outer layer, wherein the glidable interface layer is configured to facilitate sliding between the intermediate layer and the inner and/or outer layer. 
     
     
         7 . The helmet of  claim 1 , wherein the inner, outer, and/or intermediate layer comprises a colorimetric indicator configured to indicate the severity of an impact sustained by the helmet. 
     
     
         8 . The helmet of  claim 1 , wherein an alternate fixation site between the intermediate layer and the inner or outer layer comprises a unidirectional coupling, and wherein the unidirectional coupling permits tangential translation at the unidirectional coupling site between the intermediate layer and in the inner or outer layer in only one direction. 
     
     
         9 . The helmet of  claim 8 , wherein the unidirectional coupling is configured such that a tangential impact deforms the intermediate layer only in compression, and not in tension. 
     
     
         10 . The helmet of  claim 8 , wherein the unidirectional coupling comprises an edge or hook on the inner and/or outer layer that overlaps at least a portion of the intermediate layer. 
     
     
         11 . The helmet of  claim 1 , wherein the outer and/or inner layer is perforated with a plurality of holes having an average diameter of from about 1 mm to about 3 cm. 
     
     
         12 . The helmet of  claim 1 , wherein the alternate fixation sites comprise removable couplings. 
     
     
         13 . The helmet of  claim 1 , wherein the alternate fixation sites comprise elastic couplings, and wherein the elastic couplings are configured to allow relative displacement between the inner layer and outer layer in an impact. 
     
     
         14 . A helmet for protecting a head during an impact, comprising:
 an outer layer;   an inner layer; and   at least one deformable intermediate layer, wherein the intermediate layer comprises a honeycomb, and wherein the helmet is configured to permit relative tangential displacement of the inner and/or outer layers with respect to one another.   
     
     
         15 . The helmet of  claim 14 , wherein the honeycomb is an aluminum honeycomb. 
     
     
         16 . The helmet of  claim 14 , wherein the honeycomb comprises a plurality of honeycomb elements configured to retain a substantially symmetric shape and/or resist buckling when the intermediate layer adopts a curved or substantially spherical shape. 
     
     
         17 . The helmet of  claim 14 , wherein the honeycomb is configured to crumple and absorb an impact force component actin substantially perpendicular to the outer layer. 
     
     
         18 . The helmet of  claim 17 , wherein the honeycomb provides a substantially linear crush response. 
     
     
         19 . The helmet of  claim 17 , wherein the honeycomb is pre-crushed by 1-20% of its thickness. 
     
     
         20 . The helmet of  claim 14 , wherein the intermediate layer comprises at least two layers of honeycomb, wherein each layer of honeycomb has a different crush resistance. 
     
     
         21 . The helmet of  claim 14 , wherein the honeycomb cells are at least partially filled with an additional energy-absorbing material. 
     
     
         22 . The helmet of  claim 21 , wherein the additional energy-absorbing material comprises an expanded foam. 
     
     
         23 . The helmet of  claim 21 , wherein the additional energy-absorbing material has a non-uniform thickness, and wherein the additional energy-absorbing material is configured such that the intermediate layer becomes progressively more crush-resistant as it is crushed in a direction tangential to the outer layer and/or in a direction perpendicular to the outer layer. 
     
     
         24 . The helmet of  claim 14 , wherein the outer layer and/or inner layer is permeable to air and configured to allow for ventilation through the honeycomb. 
     
     
         25 . A method for making a helmet that mitigates linear and rotational acceleration of a head during impact, the method comprising:
 suspending an intermediate layer between an outer layer and an inner layer, wherein suspending the intermediate layer comprises coupling the intermediate layer to the inner layer and the outer layer at alternate fixation sites, wherein the intermediate layer is configured to absorb impact energy by deformation in a direction perpendicular to the outer layer and in a direction tangential to the outer layer.