Protective helmet with multiple energy management liners
A helmet for rotational energy management can include an outer energy management layer comprising an outer surface and an inner surface opposite the outer surface. The inner surface can comprise a first slidable finish comprising a first glaze comprising a thickness less than or equal to 2 millimeters (mm). An inner energy management layer can be disposed within the outer energy management layer and further comprise an outer surface oriented towards the outer energy management layer and an inner surface opposite the outer surface. The outer surface can comprise a second slidable finish that directly contacts the first slidable finish. The second slidable finish can comprise a second glaze comprising a thickness less than or equal to 2 mm. A space between the first slidable finish and the second slidable finish can be devoid of a lubricant and devoid of any interstitial slip layer.
1. A protective helmet for rotational energy management, comprising:
an outer energy management layer formed of a first material and comprising a first lateral side and a second lateral side, and an outer surface of the outer energy management layer and an inner surface of the outer energy management layer opposite the outer surface of the outer energy management layer, wherein the inner surface of the outer energy management layer comprises an integrally formed first slidable finish, the first slidable finish comprising a first glaze of the first material such that the first slidable finish is part of and not removable from the outer energy management layer; and
an inner energy management layer formed of a second material and disposed within the outer energy management layer and further comprising an outer surface of the inner energy management layer oriented towards the outer energy management layer and an inner surface inner energy management layer opposite the outer surface of the inner energy management layer, wherein the outer surface of the inner energy management layer extends continuously from the first lateral side to the second lateral side of the outer energy management layer, and wherein the outer surface of the inner energy management layer comprises an integrally formed second slidable finish that directly contacts the first slidable finish, the second slidable finish comprising a second glaze of the second material such that the second slidable finish is part of and not removable from the inner energy management layer;
wherein the first slidable finish is configured to directly mate with the second slidable finish to form a low friction interface between the inner surface of the outer energy management layer and the outer surface of the inner energy management layer; and
wherein the first slidable finish and the second slidable finish are configured to move relative to each other along the low friction interface in response to an impact.
2. The protective helmet of claim 1 , wherein:
the first glaze comprises a thickness less than or equal to 1 millimeter (mm); and
the second glaze comprises a thickness less than or equal to 1 mm.
3. The protective helmet of claim 2 , wherein the first slidable finish and the second slidable finish each comprise a surface texture skewness of less than or equal to 1 mm.
4. The protective helmet of claim 3 , wherein:
the outer energy management layer comprises expanded polystyrene (EPS), expanded polypropylene (EPP), expanded polyurethane (EPU), or expanded polyolefin (EPO);
the glaze of the first slidable finish comprises EPS, EPP, EPU, or EPO;
the inner energy management layer comprises EPS, EPP, EPU, or EPO; and
the glaze of the second slidable finish comprises EPS, EPP, EPU, or EPO.
5. The protective helmet of claim 1 , wherein a first surface texture style on the first slidable finish is identical to a second surface texture style on the second slidable finish.
6. The protective helmet of claim 1 , further comprising:
an outer shell; and
the outer energy management layer disposed within the outer shell and the outer surface of the outer energy management layer oriented towards the outer shell.
7. The protective helmet of claim 1 , wherein the first slidable finish is configured to slide a distance past the second slidable finish along the low friction interface in response to a helmet impact to thereby reduce an amount of energy transferred to a head of a user.
8. A protective helmet for rotational energy management, comprising:
an outer energy management layer formed of a first material and comprising a first lateral side and a second lateral side, and an outer surface of the outer energy management layer and an inner surface of the outer energy management layer opposite the outer surface of the outer energy management layer, wherein the inner surface of the outer energy management layer comprises an integrally formed first slidable finish, the first slidable finish being part of and not removable from the outer energy management layer; and
an inner energy management layer formed of a second material and disposed within the outer energy management layer and further comprising an outer surface of the inner energy management layer oriented towards the outer energy management layer and an inner surface of the inner energy management layer opposite the outer surface of the inner energy management layer, wherein the outer surface of the inner energy management layer extends continuously from the first lateral side to the second lateral side of the outer energy management layer, and wherein the outer surface of the of the inner energy management layer comprises an integrally formed second slidable finish that directly contacts the first slidable finish, the second slidable finish being part of and not removable from the inner energy management layer,
wherein the first slidable finish is configured to directly mate with the second slidable finish to form a low friction interface between the inner surface of the outer energy management layer and the outer surface of the inner energy management layer, and
wherein the first slidable finish and the second slidable finish are configured to move relative to each other along the low friction interface in response to an impact.
9. The protective helmet of claim 8 , wherein:
the first slidable finish comprises a first glaze comprising a thickness less than or equal to 2 mm; and
the second slidable finish comprises a second glaze comprising a thickness less than or equal to 2 mm.
10. The protective helmet of claim 9 , wherein the first slidable finish and the second slidable finish each comprise a surface texture skewness of less than or equal to 1 mm.
11. The protective helmet of claim 10 , wherein:
the outer energy management layer comprises expanded polystyrene (EPS), expanded polypropylene (EPP), expanded polyurethane (EPU), or expanded polyolefin (EPO);
the glaze of the first slidable finish comprises EPS, EPP, EPU, or EPO;
the inner energy management layer comprises EPS, EPP, EPU, or EPO; and
the glaze of the second slidable finish comprises EPS, EPP, EPU, or EPO.
12. The protective helmet of claim 8 , further comprising:
an outer shell; and
the outer energy management layer disposed within the outer shell and the outer surface of the outer energy management layer oriented towards the outer shell.
13. The protective helmet of claim 8 , wherein the first slidable finish is configured to slide a distance past the second slidable finish along the low friction interface in response to a helmet impact to thereby reduce an amount of energy transferred to a head of a user.
14. A protective helmet for rotational energy management, comprising:
an outer energy management layer formed of a first material and comprising a first lateral side and a second lateral side, and an outer surface of the outer energy management layer and an inner surface of the outer energy management layer opposite the outer surface of the outer energy management layer, wherein the inner surface of the outer energy management layer comprises an integrally formed first slidable finish, the first slidable finish being part of and not removable from the outer energy management layer; and
an inner energy management layer formed of a second material and disposed within the outer energy management layer and further comprising an outer surface of the inner energy management layer oriented towards the outer energy management layer and an inner surface of the inner energy management layer opposite the outer surface of the inner energy management layer, wherein the outer surface of the inner energy management layer extends continuously from the first lateral side to the second lateral side of the outer energy management layer, and wherein the outer surface of the inner energy management layer comprises an integrally formed second slidable finish that directly contacts the first slidable finish to form a low friction interface between the inner surface of the outer energy management layer and the outer surface of the inner energy management layer, the second slidable finish being part of and not removable from the inner energy management layer.
15. The protective helmet of claim 14 , wherein:
the first slidable finish comprises a first glaze comprising a thickness less than or equal to 2 mm; and
the second slidable finish comprises a second glaze comprising a thickness less than or equal to 2 mm.
16. The protective helmet of claim 15 , wherein the first slidable finish and the second slidable finish each comprise a surface texture skewness of less than or equal to 1 mm.
17. The protective helmet of claim 16 , wherein:
the outer energy management layer comprises expanded polystyrene (EPS), expanded polypropylene (EPP), expanded polyurethane (EPU), or expanded polyolefin (EPO);
the glaze of the first slidable finish comprises EPS, EPP, EPU, or EPO;
the inner energy management layer comprises EPS, EPP, EPU, or EPO; and
the glaze of the second slidable finish comprises EPS, EPP, EPU, or EPO.
18. The protective helmet of claim 16 , wherein a space between the first slidable finish and the second slidable finish is devoid of a lubricant and devoid of any interstitial slip layer to facilitate relative movement between the first slidable finish and the second slidable finish at a time of impact.
19. The protective helmet of claim 14 , further comprising:
an outer shell; and
the outer energy management layer disposed within the outer shell and the outer surface of the outer energy management layer oriented towards the outer shell.
20. The protective helmet of claim 14 , wherein the first slidable finish is configured to slide a distance past the second slidable finish along the low friction interface in response to a helmet impact to thereby reduce an amount of energy transferred to a head of a user.