Mazda have developed an impact absorbing structure for use in car bonnets. The structure is called “shock cone aluminium hood”. The new structure was designed to minimise head injuries sustained by pedestrians when they were struck by cars. Data indicates that 30% of traffic related deaths are pedestrians, with 60% of these being attributed to fatal head injuries.
The shock cone design differs from standard automotive bonnets in that it has an inner panel with uniquely shaped craters, similar to cones. These structures are called shock cones and effectively absorb impact loads across the whole surface of the bonnet. They effectively reduce the extent of head injuries sustained by pedestrians in traffic accidents. Results from European NCAP testing indicate that injuries may be reduced by as much as 50% compared to conventional aluminium bonnets.
Standard bonnets consist of an outer skin reinforced by a metallic skeleton. This structure, while controlling crumpling to some degree, has hard points and is not as effective at absorbing impacts.
The improved impact absorbing properties of the shock cone aluminium hood has enabled designers to reduce the clearance required between the engine and bonnet by about one-third or approximately 30mm. When combined with the low profile Mazda rotary engine, designers were able to give the RX-8 a more aggressive stance than would be possible using a more conventional bonnet design.
The new design also offers improved rigidity. This has resulted in a bonnet that is lighter.
The shock cone aluminium hood will be first used in the Mazda RX-8, due out in spring (northern hemisphere), but will be gradually incorporated into all Mazda models.