Pyrotechnic pretensioners are widely used components in today's state-of-the- art occupant restraint systems. Their objective is to pull in belt in a crash situation and thus tighten the occupant to the seat in an early crash phase. One characteristic physical behaviour of pyrotechnic pretensioners is the load case dependent performance. That is, the belt pull in is in general a function of belt load. Classical modelling of pretensioners apply a force versus displacement characteristic. This approach is valid within given boundary conditions. In order to account for transferability to other loadcases, extended modelling techniques are investigated. Based on the existing thermodynamic approaches of airbag modelling, the paper presents an investigation to model pyrotechnic pretensioners, both in detailed component simulations as well as in occupant restraint simulations. Application examples in analysis of structural integrity as well as in occupant restraint simulations are shown. The presented approach shows potential of improvement in the modelling of pyrotechnic pretensioners. Especially the transferability between various loadcases can be modelled in a more promising way. Open points for further investigations are: 1. Validation: The modelling approach needs to be validated in various loadcases, both in structural analysis and occupant restraint simulation. Measures of belt forces and pressure curves need to be compared with measurements of corresponding tests. 2. Coupling of ballistic behaviour: Up to now the presented approach does not take into account potential influence of pressure to the burning behaviour of the propellant. As well the energy losses due to heat transfer to structural parts is not taken into account yet. Coupling of ballistic codes to the existing FE or MBS codes needs to be incorporated to the simulation models in order to overcome those mentioned shortages. First models using coupled ballistic codes are currently running at TRW.


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    Title :

    Modelling of pyrotechnic pretensioners


    Additional title:

    Modellierung pyrotechnischer Vorspanneinrichtungen


    Contributors:
    Elsäßer, K. (author) / Kotzschmar, R. (author) / Zecha, H. (author)


    Publication date :

    2006


    Size :

    8 Seiten, 8 Bilder, 2 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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