Sport and transport protective helmets are becoming more sophisticated, as cyclists, motorbike riders and sportsmen become increasingly safety-conscious. At this time, amidst innovations and advancements, helmets still rely heavily on plastic foams to absorb energy.
Masuri, the most widely used helmet manufacturer in professional cricket, boasts innovative designs that are subject to stringent testing. In the new Masuri Vision Series, there are three layers of protection. First, there is the polycarbonate inner shell. The shell is covered by an expanded, rigid and tough polystyrene crush zone. Finally, a very thin polypropylene outer shell completes the helmet.
Until recently, neither the British nor Australian/NZ Standards included projectile testing, nor did they include any provision for helmet/faceguard failure due to contact with the face. Impact energy levels and impact areas for the associated testing protocols did not seem to match impact forces and locations that were likely to occur during cricket batting situations.
In contrast, the North American National Operating Committee on Standards for Athletic Equipment (NOCSAE) testing of baseball catchers' helmets appeared to utilise similar types of ball, ball speed and replicated the head area requiring protection in cricket. The NOCSAE specification is updated annually and involves both drop and projectile testing (involving a baseball being fired at the helmet/face guard). Accordingly, the specification for head protectors in cricket was updated and published in December 2013.
Unfortunately it took the tragic death of Australian cricketer Phillip Hughes to focus the world’s attention on sporting headwear safety standards. Masuri found themselves at the centre of a media storm, as they were the brand of helmet Phillip Hughes was wearing when he was hit, albeit an older model. Hughes' brain injury was caused by being hit at the base of the skull where it is very difficult to adequately protect without restricting a batsman’s head movement.
Masuri has since announced their concept-in-development of a protection system for the back of the head that it believes will protect that vulnerable area but still allow movement. The Masuri branded design, StemGuard, combines an impact-modified thermoplastic polyurethane (TPU) honeycomb with military grade crush foam to maximise impact absorption, giving players much more confidence when batting. The StemGuard attaches to the existing Masuri Vision Series helmets with moulded clips.
Maybe soon we can say goodbye to polystyrene foam altogether? In what looks like an ordinary bicycle helmet, Swedish designers have replaced Styrofoam with a new shock-absorbing renewable and biodegradable wood-based material. The helmet is intended to draw attention to the possibilities of using wood cellulose as a sustainable alternative to Styrofoam and other foams from synthetic polymers.
Researcher Lars Wågberg, a professor in Fibre Technology at Stockholm's KTH Royal Institute of Technology, says the wood-based foam material offers comparable properties to Styrofoam. "But even better, it is from a totally renewable resource — something that we can produce from the forest," Wågberg says.
Trademarked under the name, Cellufoam, the helmet is produced by Cellutech, a Stockholm startup that specialises in cutting edge materials made from wood.
Production begins with wood cellulose nanofibres, or fibrils, that are modified and mixed with a foaming agent, water and air. Through the process of Pickering stabilisation, these particles hold the air-bubbles in a way that is much better than by using simple surfactants, he says.
While the Cellufoam is being showcased as a bicycle helmet material, Wågberg says that by using different surface treatments and combining it with other components, it could also be suitable for flame retardant material, water filtration and antibacterial material.
Urethane foams come out top
The latest hockey helmet from Bauer RE-AKT 75 is the best performing helmet on the consumer market, according to the Virginia Tech Helmet Ratings system, called the Hockey Summation of Tests for the Analysis of Risk (STAR) evaluation system. The STAR evaluation system was developed over three years and initially released in April 2015. Virginia Tech researchers rate the Bauer helmet the highest of 38 hockey helmet models that have been tested to date, earning three stars. The RE-AKT 75 helmet uses Poron, a protective foam product manufactured by Rogers Corporation (USA). Made from polyurethane (PU) foam, Poron has the ability to absorb and dissipate a huge amount of energy during impacts.
The helmet also features the so-called Seven Technology Liner System - an impact attenuation system designed to more effectively manage energy transfer from direct high energy impacts. Upon impact, the Seven Technology Liner System compresses to laterally displace energy. Within seconds it completely resets and is ready for the next impact.
“The Bauer RE-AKT 75 did the best job of managing impact energy and lowering head acceleration of all the hockey helmets we’ve tested to date,” said Steve Rowson, director of the Virginia Tech Helmet Laboratory and an assistant professor in the Department of Biomedical Engineering and Mechanics in Virginia Tech's College of Engineering. “While there is still room for improvement, this places the new Bauer hockey helmet at the very top of our hockey helmet ratings.”
A paper published in the Annals of Biomedical Engineering, “Hockey STAR: A Methodology for Assessing the Biomechanical Performance of Hockey Helmets,” details the approach that Rowson and his colleagues take to test the protective capabilities of the helmets.
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