Head and Neck Support Systems (HANS)

Abstract

Only recently has the racing industry acknowledged that the number one cause of racing-related fatalities is basilar skull fractures from excessive head motions and neck loading. Racing legend Dale Earnhardt's death proved to the racing world and the general public that what appears to be a low impact crash can be fatal. Under development and extensively tested for over a decade, there is a device that can reduce the risk of serious injury or even death to the driver in such a crash. It is the Head And Neck Support (HANS) device.

The HANS, head and neck support was invented by Dr. Robert Hubbard, a biomechanical engineering Professor at Michigan State University. Many debilitating or fatal head and neck injuries could be prevented using this system. In 2000, compact versions of HANS (Figure 2) were developed for CART, IRL, F1, NASCAR, NHRA, ASA, Sports cars, Power Boating and many other racing series.
Extensive testing has proven that HANS consistently reduces the injury potential from head motions and neck loads.
The latest example of the engineers' efforts to make Grand Prix racing as safe as possible is the new Head And Neck Support (HANS). The system is easy to use and extremely effective. It prevents over-extension of the driver's neck region in the event of extreme deceleration. It is designed to 'complete' driver head protection, covering the one aspect to be still exposed.
Forward movement of the head and neck has, until now, been the only unrestrained area in driver impact safety. Extensive research and testing has resulted in what experts now believe to be a practical solution to the issue.
HANS features a carbon fibre collar connected securely to the upper body, with straps attaching it to the helmet. The four main parts of the system are:
1. Support brace- rests on shoulders.
2. Padding- is 'fine tuned' for both comfort and fit.
3. Tethers-high strength Nomex tethers secure helmet to support brace.
4. Anchoring- complete system is secured by standard 75mm shoulder straps.
The fundamental purpose of the system is to effectively form a single 'body' of the head and torso.
By purposely directing the loads experienced following impact, the driver's helmet is able to assist in dissipating the loads. HANS is intended to prevent driver's head from being thrown forward in an accident, a common 'whiplash' situation which could lead to an over extension of the spinal column.
HANS features a carbon fibre collar connected securely to the upper body, with straps attaching it to the helmet. The four main parts of the system are:
1. Support brace- rests on shoulders.

2. Padding- is ‘fine tuned’ for both comfort and fit.
3. Tethers-high strength Nomex tethers secure helmet to support brace.
4. Anchoring- complete system is secured by standard 75mm shoulder straps

The fundamental purpose of the system is to effectively form a single ‘body’ of the head and torso. By purposely directing the loads experienced following impact, the driver’s helmet is able to assist in dissipating the loads. HANS is intended to prevent driver’s head from being thrown forward in an accident, a common ‘whiplash’ situation which could lead to an over extension of the spinal column.
Drivers face theoretical deceleration stresses of up to 80 times the force of gravity in an accident. In such a situation, the weight of the head and helmet increases quickly from 7kg to as much as 560kg. HANS would help to absorb this strain, as well as prevent the driver’s head from hitting the steering wheel or front edge of the cockpit.

Basic Concept

In a crash without HANS, the shoulder harness and seat restrain the driver’s torso, but only the neck restrains the head and helmet. The HANS device keeps the driver’s head from being pulled away from his upper body. With HANS, forces stretching the neck are reduced to less than one-fifth in a frontal collision as slow as 41 mph. The HANS works in a simple and elegant manner.
A CFRP yoke is worn by the driver fitted around his neck and under the shoulder belts. His helmet is loosely connected to this yoke by tethers ensuring free movement of the head. In a frontal crash, these tethers restrain the head with forces that directly counteract the head’s forward movements while the torso and HANS are restrained by the shoulder harness. By restraining the head to move with the torso in a crash, the head motions and forces in the neck are dramatically reduced. The helmet loading is also transferred from the base of the skull to the forehead- which is far better suited in taking the force.

Recent HANS Testing and Development

In 1997, DaimlerChrysler, Hubbard, and Downing started a cooperation to develop and evaluate HANS prototypes suitable for the FIA Formula 1 environment.
A progression of HANS prototypes were made and evaluated in many impact sled tests to develop a HANS (Figure 2) that is much smaller than the original device (Figure 1). This smaller HANS fits reclined driving positions, as is the norm in F1, CART, and IRL. Also, the smaller HANS devices have worked spectacularly well for drivers in upright seating positions such as NASCAR, ASA, TransAm, and the German Touring Car Series.
The results shown in Table 1 are from testing by DaimlerChrysler, and provide a summary of HANS’s performance in frontal crashes. These tests were run with a dummy to simulate a reclined driver with a crash sled acceleration of 45 G’s.
The results of the baseline test without HANS are shown in Table 1 relative to published injury thresholds used for passenger cars. Without HANS , the dummy’s head swung forward, hitting the steering wheel. The resultant load in the neck (the combination of the tension and shear loading of the neck) exceeded the injury threshold. Neck loading of this magnitude leads to fractures of the base of the skull (basilar skull fractures) that are the most common cause of death in racing drivers.
The HANS provided a dramatic reduction in injury potential. With HANS, the head was less likely to strike surfaces of the cockpit. The Head Injury Criterion (HIC) was used to assess the severity of direct head impacts. In most cases with HANS, the HIC were not applicable. Even so, HIC was reduced with HANS. Without HANS the head swung forward and, as will be discussed below with Figure 6, head accelerations due to head swinging without HANS were higher than with HANS where head swinging was restrained.
With HANS, the forward motions and rebound of the head were reduced. Also, the neck loads were dramatically reduced, decreasing the potential for basilar skull fractures. Chest deflections were also reduced. As the dummy was pushed against the shoulder belts, the HANS device distributed some of the force to the shoulders and away from the chest.