Who would think that the humble car seat belt mechanism could be improved upon? Well, designers at Honeywell for starters. They are claiming that seatbelt systems designed using the company’s new Securus ‘smart response’ synthetic fibre copolymer can replace load-limiting mechanical devices which perform a similar function.
Better yet, they say that car makers can continue receiving Five Star US government safety ratings while actually providing better safety for car occupants. That’s because current seatbelt systems are designed for the 50th percentile average occupant, a 79-kg (175-lb) male. Seatbelts with Honeywell’s Securus fibre work for a broad range of body types – children and smaller women, as well as those of use who enjoy eating voluminous amounts of junk food.
Honeywell’s ‘smart response’ fibres are formulated to elongate a specific amount within a pre-defined load range. Used in webbing for seatbelt systems, the fibres provide a load-limiting capability that mimics the three-step action of the mechanical load limiters used in constant force retractors (CFRs).
During a collision, seatbelts made with Securus fibres first hold the occupant in position, then elongate just enough to absorb the energy of the body’s forward motion, and finally stop elongating to prevent an occupant from hitting the steering wheel, dashboard, or windshield.