The NOCSAE headform

The NOCSAE headform is one of the pieces of equipment specified in our standards for headgear and helmet testing. Headforms “wear” helmets during testing. As the helmet (with a headform inside) is impacted by various methods, the headform takes readings about these impacts.

Inside the headform, at its center of gravity, it has a triaxial accelerometer, which is a specialized sensor. The 3 NOCSAE headformsheadform measures accelerations from three different directions and G-force readings are captured 1000 times per second during each impact event of a test. A single helmet test involves 34 separate impacts to 6 established locations on the helmet, as well as impacts to randomly selected locations and impacts at various speeds and temperatures. In NOCSAE testing standards the headform is used in the drop test and the pneumatic ram test methods.

The drop test
The NOCSAE drop test method defines impact limits for linear acceleration. For the drop test, a headform is attached to a twin-wire impactor that drops the headform and helmet onto a steel anvil covered with a ½-inch, hard rubber pad. A single helmet test involves 29 impacts (at specific speeds) onto seven different helmet impact locations, including three random impact locations. There are 4 lower-velocity impacts, and 4 impacts at high temperatures. The helmet must pass each impact event.

The pneumatic ram test
For the pneumatic ram test, the headform is mounted to a linear-motion bearing table, which allows the headform and helmet to slide after an impact. Helmets are struck at 19.6 meters (about 18 yards) per second on six different helmet locations, including one random location. The pneumatic ram impactor can deliver impacts in locations and from directions that are not possible with the drop test system. Helmets must meet the standard at all impacts of the pneumatic ram test.

Watch these short videos of the twin-wire drop and the pneumatic ram.