Hybrid III Neck for Crash Dummies – Full Story
The FIA Institute and its partners have developed a new neck for crash-test dummies, that better examines the extreme forces experienced by racing drivers.
More than in any other sport, the neck is a crucial competitive component in motor racing because its muscular strength and stamina are pushed to the limit by the rigours of a 70-lap race. Weight training for the neck is, therefore, vital for drivers.
The g-forces experienced by Formula One drivers for instance, can multiply the weight of their heads by a factor of five. That’s the equivalent of strapping on a large bucket of sand to your head for 90 minutes while driving a very fast car around a complicated track and dicing with rival drivers – often in extreme heat.
All of which means the FIA Institute has to use specially adapted crash test dummies to accurately measure the extraordinary forces in play on a racing drivers body. This isn’t so much to reflect the increased strength of a driver’s well-exercised neck, but rather to ensure the safety devices protecting it, such as frontal head restraints and racing nets, remain as effective once the neck has been stretched by such unnatural loads.
And that’s why the Institute and its partners have adapted the latest Hydrid lll neck – usually used on dummies design for road car crash tests – to better represent the types of injuries suffered by racing drivers.
Already the Hybrid lll is a highly developed piece of kit: its construction uses segmented aluminium and vulcanised rubber to accurately simulate the human dynamic movement/rotation flexion and extension response. The Institute and its partners have adapted this further, specifically for motor sport testing. The main change has been to remove its fixed interior cable and add an elongated version made from high-tensile, which allows the neck to stretch.
Institute Technical Advisor Andy Mellor explains: ”It is fully understood in the bio-mechanical worlds that a human neck can stretch considerably before a neck or basal skull injury is suffered. But normal dummy necks generally allow for almost zero stretch at the point where you’d be measuring fatal loads”
If the injury itself related to measurements of forces, which they typically do in most road accidents, then using this standard neck isn’t a problem. An issue arise, though, if the actual position of the head relative to the car environment or safety equipment is important – then the ability of the neck to stretch is an essential factor.
So – to take a system like the frontal head restraint – if the position of the head can change as the neck stretches, the whole geometry of the way the frontal heads restraint works also changes. The response of a driver can be quite different from the response of the dummy in a test.
“It isn’t something we’re concerned about with the current FIA-approved frontal head restraint,” says Mellor, “but it becomes a real factor for alternative restraint systems and you need to know how the position of the head is changing to understand whether or not that product is providing the right levels of safety.”
The new dummy neck is also important for testing racing nets and side supports on seats in closed cars. When you install a net it needs to be at the correct height to offer the driver protection because, if the neck stretches in a crash, then the head can easily go up and over the side of the net, which could make a significant difference to its effectiveness.
It is hoped the neck will be extremely valuable for testing neck braces in karting and motor cycling, where the dummy neck measurements must be realistic, of course, and provide the correct bio-fidelity.
Having established the need for this new neck, the Institute had two tasks. First, to define the way a human neck behaves in any given incident; then work with a company that could develop a physical mechanical neck producing those characteristics.
The Institute found the perfect partner in the US Universities Duke and Wayne State, with production capability from Denton ATD: “This team had access to information to establish the human response and are also involved in neck production for some of the dummies. They were then able to do those modification for us.”
The threshold for injury is around four kilo-newtons, at which point a human neck will stretch by about 30mm. The new design allows the motor sport neck to do this but once it get beyond the point where a human neck would break, the cable engages to stop the equipment itself from becoming damaged.
Denton ATD will provide a kit to modify the standard Hybrid lll on the latest-spec dummies. The Institute plans to use the new neck for all relevant motor sport testing involving test dummies in the future.
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