*As Featured on NI.com
Original Authors: Jim Barnes, Snell Memorial Foundation, Inc.
Edited by Cyth Systems
Designing a portable impact test application for the certification of safety helmets.
Using NI CompactDAQ to develop a high accuracy measurement system for the certification testing of sports/racing helmets.
For the past 50 years, the Snell Memorial Foundation has been a leader in helmet safety in the United States and around the world. Founded in 1957 to honor the memory of race car driver Pete Snell, who died in what should have been a survivable slow rollover crash in 1956, we are dedicated to the research, education, testing, and development of helmet safety standards. Pete’s helmet, state of the art in 1956, was not much more than a pressboard baseball cap.
There are strict certification tests that helmets, ranging from motorcross to Nascar must pass in order to be certified. Once in the certification program, the helmets are subjected to ongoing random sample tests (RSTs). The manufacturers do not know when or where we buy their helmets. By setting tough standards, tough certification testing, and follow-up RSTs, we keep only the safest equipment in our certification program.
Left: Graph of force data from helmet impact during drop testing. Right: NI cDAQ-9178 for impact test data-acquisition.
CompactDAQ is used to control the height from which the helmet under test is dropped, as well as acquiring data related to what a person's head would be subjected to upon impact.
We strive to set the toughest helmet safety standards in the world, and we are in the unique position of not only writing safety standards but also enforcing them. We do this through exhaustive, independent testing. The most critical test we perform is the helmet impact test in which we mount a helmet onto a headform equipped with an accelerometer. The helmet is elevated and then dropped onto one of several steel anvils designed to simulate various surfaces. There are roughly 36 impacts performed in a certification test series. If at any time during testing the helmet experiences more than 300 peak Gs (290 Gs in certification testing), the helmet fails the test.
We use the digital I/O capabilities of NI CompactDAQ to raise the elevator to a height that provides the proper impact energy and also to initiate the drop sequence. As the helmet is falling, a sensor passes through a velocity gate, and we use the counter/timer function to measure the helmet velocity just prior to impact. This triggers the data acquisition system, which measures the acceleration that the head feels during impact.
Snell Memorial Foundation is a nonprofit organization, and cost-effectiveness is a primary concern for our work. A system upgrade such as the one we required is a major budget consideration, and for this reason we were very deliberate in our search for a new hardware package.
Jim Barnes, Snell Memorial Foundation, Inc.
Edited by Cyth Systems