Restraint systems for front seats have experienced continual improvement in recent years, in particular through the introduction of airbags. The standard for rear seats, however, is still the conventional three-point belt on outer seats and the lap belt for the middle seat position. As using airbags in rear seats is very problematic, the feasibility and protective effect will be examined of a belt system equipped with a belt pretensioner and a load limiter. To do so, first the marginal conditions constituted by legislation, findings from accident investigations, and seat position and belt geometry in rear seats are discussed in detail. Results from sled testing and MADYMO simulations allow the following to be said: Optimized belt systems very much reduce thorax loading, the largest effect for chest deflection coming from the load limiter, but for V*C, on the other hand, from the pretensioner. It emerges that a vehicle crash pulse that is 30% harder with an optimized belt system produces lower thorax loading values for rear seat occupants than a corresponding "softer" pulse with a conventional three-point belt.
Abstract