Helmet & Airbag Interaction – Full Story
AIMSS was recently asked to investigate and provide advice on what effect the use of safety helmets by vehicle occupant/s may have on correct airbag function in passenger vehicles fitted with such.
Some of the questions asked were:
- Has there been any crash testing done to determine the safety outcomes from the interaction of helmets and airbag deployment?
- What are the potential injury risks?
- If the airbag is designed for a predetermined mass contacting it, does the additional weight of the helmet impact on the effectiveness and deployment of the airbag?
- Also in relation to side air bags, if they are designed for a predetermined distance between the head and the side curtain airbags, could the helmet have an influence?
These questions were put to Dr Michael Henderson, AIMSS Director and Chairman of the AIMSS Research Advisory Group (RAG) and Professor Jack McLean also a Director of AIMSS and member of RAG.
Dr Henderson explained that doubts about the possibly deleterious interaction of a full-face helmet and an airbag were first raised when the Sports Car Club of America (SCCA) issued an following advisory note in 2004, recommending that full-face helmets not be used in vehicles with functional airbag systems.
This advisory was later withdrawn, as a result of further research carried out by the FIA Institute in 2005. The Institute retained Hubert Gramling, a former Mercedes-Benz engineer intimately involved in the design and development of airbags for the Mercedes-Benz company. Gramling concluded from his research that the use of both full-face and open-face helmets may be regarded as compatible with airbag deployment.
In understanding the function of the deploying airbag, Dr Henderson said, “the airbag is supposed to fully deploy before the head (helmeted or not) comes into contact with it. The only way that the applied force could possibly be excessive is when the head is contacted by the airbag while it is still expanding, which is recognised as a risk to unrestrained occupants and those who sit too close to the steering wheel. However, Gramling was careful to include ‘out-of-position’ dummies in the crash sled tests he arranged (see attached videos), showing that the helmet-airbag interaction did not give rise to unfavourable results in terms of head accelerations and neck forces. In summary, there’s no reason why restrained drivers should worry about an airbag if they are wearing a helmet.
Professor McLean further explained, “in a side impact situation any earlier contact with the deploying side air bag would be mitigated somewhat by the added mass of the head/helmet, thereby reducing the acceleration of the head. Given the commonly occurring substantial deformation of the side of the car in a side impact I would rather have a helmet”..….
Figure 1 (above)
The data in Figure 1 shows the forces generated to the head and neck of the dummy for each test when impacted by the deploying airbag with and without helmets.
The ‘Threshold’ figures are the forces and accelerations for the head and neck of a human being over which there is a high risk of serious or fatal injury.
These static tests use only the force generated by the deploying airbag and interacting with the dummy’s head. They were also conducted ‘out of position’, whereby the location of the crash dummy is purposely positioned close to the steering wheel. This intentionally exposes the head and neck to potentially hazardous forces.
Figure 2 (above)
The data in Figure 2 shows the forces generated to the head and neck of the dummy for each test when impacted by the deploying airbag with and without helmets.
These dynamic tests were conducted using a 30 mph (48 km/h), standard 27g car crash pulse with the dummy located in the normal and restrained (belted) seating position.
Video 1 – Dynamic Test – Open Face Helmet[raw][/raw]
Video 2 – Dynamic Test – Full Face Helmet[raw][/raw]
Video 3 – Dynamic Test – Airbag No Helmet[raw][/raw]
Video 4 – Dynamic Test – No Airbag Full face Helmet[raw][/raw]
Video 5 – Static Test – Open Face Helmet Lower AirBag Position[raw][/raw]
Video 6 – Static Test – Full Face Helmet Lower AirBag Position[raw][/raw]
Video 7 – Static Test – No Helmet Lower AirBag Position[raw][/raw]