Method and apparatus for testing football helmets

• US 20040074283A1
• Filed: 06/13/2003
• Published: 04/22/2004
• Est. Priority Date: 06/14/2002
• Status: Active Grant

• Current Assignee: Riddell Incorporated (BRG Sports, Inc.)
• Original Assignee: Riddell Incorporated (BRG Sports, Inc.)
• Inventors: Withnall, Christopher R.P., Bayne, Timothy D.
• Granted Patent: US 6,871,525 B2
• Time in Patent Office: Days
• US Class Current: 73/12.12
• CPC Class Codes: G01M 7/08 Shock-testing
• CPC Class Codes: G01N 2203/0016 Tensile or compressive
• CPC Class Codes: G01N 2203/0676 Force, weight, load, energy, speed or acceleration
• CPC Class Codes: G01N 3/32 by applying repeated or pulsating forces

Abstract

A method and apparatus for testing a football helmet utilizes a weighted pendulum arm to impart an impact force upon the helmet. Linear head acceleration and rotational head acceleration caused by the impact force is measured and a Head Impact Power Index is computed and used as a standard to judge the ability and effectiveness of the football helmet in preventing injury to a football player.

Claims

1. A method for testing a football helmet, having an outer surface and an upper portion comprising the steps of:

striking the football helmet to impart an impact force, and

measuring linear head acceleration and rotational head acceleration caused by the impact force.

2. The method of claim 1, including the step of utilizing a helmet which is placed upon a headform.

3. The method of claim 2, including the step of utilizing a neck with the headform to provide a headform-neck assembly.

4. The method of claim 3 wherein the headform-neck assembly is disposed upon a base.

5. The method claim 1, wherein the helmet is struck by a weight suspended from a pendulum arm.

6. The method of claim 5, wherein the weight is a on impact head.

7. The method of claim 6, wherein the impact head has a domed spherical outer surface which strikes the football helmet.

8. The method of claim 5, wherein the pendulum arm rotates about a point disposed above the helmet.

9. The method of claim 1, including the step of striking the helmet at a plurality of locations on the outer surface of the helmet.

10. The method of claim 7, including the step of providing the domed spherical outer surface with a radius of curvature which generally corresponds to the radius of curvature of the upper portion of the football helmet.

11. The method of claim 7, including the step of providing a layer of plastic material upon the domed spherical outer surface, the plastic material generally corresponding to the same material of which the football helmet is made.

12. The method of claim 2, including the step of utilizing a plurality of accelerometers within the headform to measure the linear head acceleration and rotational head acceleration.

13. The method of claim 12, including the step of utilizing nine accelerometers.

14. The method of claim 1, including the step of computing a maximum Head Impact Power Index (HIPmax) for the football helmet, wherein

Power=P=Σ

m{overscore (a)}·

{overscore (v)}+Σ

I{overscore (α

)}·

{overscore (ω

)}

where;

{overscore (a)}=linear acceleration (m/s²)

v=linear velocity (m/s)

I=mass moment of inertia (Nms²)

m=mass (kg)

$\begin{array}{c}\mathrm{HIP}=<br><br>4.50<br><br>a_x<br><br>\int <br><br>a_x<br><br><br><br>t+4.50<br><br>a_y<br><br>\int <br><br>a_y<br><br><br><br>t+4.50<br><br>a_z<br><br>\int <br><br>a_z<br><br><br><br>t+\\ <br><br>0.016<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\alpha <br><br>}}_x<br><br>\int <br><br>{\mathrm{\alpha <br><br>}}_x<br><br><br><br>t+0.024<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\alpha <br><br>}}_y<br><br>\int <br><br>{\mathrm{\alpha <br><br>}}_y<br><br><br><br>t+0.022<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\alpha <br><br>}}_z<br><br>\int <br><br>{\mathrm{\alpha <br><br>}}_z<br><br><br><br>t\end{array}$

15. The method of claim 14, including the step of approving a football helmet which has an HIPmax of less than approximately 12.8 kw.

16. The method of claim 1, wherein the football helmet is struck with a weight that is moving at a speed of approximately 5.4 m/s.

17. An apparatus for testing a football helmet, having an outer surface and an upper portion, comprising:

a pendulum arm having first and second ends;

the first end of the pendulum arm being mounted for rotational movement;

a weight disposed on the second end of the pendulum arm; and

a headform disposed upon a base, the headform including a plurality of accelerometers, adapted to measure linear head acceleration and rotational head acceleration caused by an impact force upon the headform, whereby the football helmet may be tested after the football helmet is placed on the headform and struck with the weight.

18. The apparatus of claim 17, including a neck associated with the headform to provide a headform-neck assembly, the headform-neck assembly being disposed upon the base.

19. The apparatus of claim 17, wherein the weight is an impact head.

20. The apparatus of claim 19, wherein the impact head has a domed spherical outer surface which is adapted to strike the football helmet.

21. The apparatus of claim 20, wherein the domed spherical outer surface has a radius of curvature which generally corresponds to the radius of curvature of the upper portion of the football helmet.

22. The apparatus of claim 20, wherein a layer of plastic material is disposed upon the domed spherical outer surface, the plastic material generally corresponding to the same material of which the football helmet is made.

23. The apparatus of claim 17, wherein the first end of the pendulum arm is disposed above the football helmet to be tested.

24. The apparatus of claim 17, wherein the pendulum has a minimum length of approximately 200 cm.

25. The apparatus of claim 17, wherein the headform is adjustably mounted with respect to the base, so that when a helmet to be tested is placed on the headform to be struck by the weight, the helmet may be struck at any desired location upon the outer surface of the football helmet.

26. The apparatus of claim 17, wherein the headform is adjustably mounted with respect to the base to permit movement of the headform with respect to the base in a plurality of directions.