VAS SCREEN SYSTEM


The impact energy can be attenuated if the head can keep moving.


It can be roughly divided into three components: scalp, skull, and brain. The function of a motorcycle helmet is to minimize and control the impacts suffered by the brain. Laboratory test standards vary in certain respects, but in general they all define levels of shock absorption. These levels are tested by dropping a helmet, with a steel head inside, from a predetermined height onto a steel anvil. Accelerometers located inside the head measure the forces endured in these drop impacts to verify shock absorption performance. Standards like Snell set criteria for testing at a fairly high level to get certification approval.


Upon impact, the helmet acts as a shock absorber: the outer shell deflects energy and the inner lining absorbs energy as it crushes, slowing down the impact speed. The examination of the results obtained in the control of the impact energy corresponding to the standard shows great differences with respect to that of a real accident, which occurs in a demanding and unpredictable environment.


The kinetic energy of a moving object increases proportionally to the square of the speed. Therefore, an urban motorcyclist moving at the legal speed limit may have a kinetic energy 10 times greater than that corresponding to the speed of a drop test. It is not foreseeable that any helmet, regardless of brand or design, will directly absorb such energies.


Therefore, Arai believes that "diversion" features must be important to divert energy while keeping the head moving. For potential impacts with energies higher than the standards, and even higher than what a helmet can directly withstand, Arai has always, throughout its history, tried to make helmets that are more rounded, smooth and resistant.


However, even on the Arai, there are limitations to how smooth and rounded a helmet can be due to the restrictions of its unique pivot visor mechanism. The geometry of today''''s screen systems require a high pivot position. This elevated pivot point falls within the test area of the norm, crossing the norm limit lines at the left and right temples.


The screen is attached to the helmet by means of a support and pivot mechanism. To preserve a smooth and level transition between screen and shell, the area of the latter where said mechanism is attached must have a sunken area or a hole. Current screen systems, with part of the mechanism inside the test area, prevent maintaining a curved, smooth and continuous surface of the shell.
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