A Method to Evaluate the Energy Capability of Seat Belt Pretensioners

Current performance specifications of seat belt pretensioners include web retraction and belt load. These criteria may adequately represent the performance requirements of a pretensioner in a restraint system. However, by themselves, they are inadequate to evaluate potential design modifications to improve efficiency levels and thus increase energy output of the pretensioner.

This paper demonstrates a non-linear phenomenon associated with web retraction and the belt load during pretensioning. It is this non-linear behavior that promotes the insensitivity for use of web retraction in predicting the energy output of a pretensioner with design modifications. This paper proposes an energy measuring method that can be used to more accurately measure the energy output of a pretensioner and then be used to evaluate the effects on output of a pretensioner due to design modifications.