This study addresses the biodynamic response mitigation of an impact of a helicopter with the ground at a specified sink rate, in which a vertically stroking crew seat with an adaptive magnetorheological energy absorber (MREA), which has a controllable load-stroke profile, is employed to protect the occupant from injury. Under consideration is a multiple degree-offreedom biodynamic lumped parameter model (BLPM) of a seat/occupant falling at a prescribed initial sink rate. The BLPM is comprised of four human body parts: pelvis, upper torso, viscera and head. The governing equations of the MREA seat suspension were derived using key parameters such as available energy absorber stroke and magnetorheological yield force. The MREA was modeled using nonlinear Bingham-plastic model incorporating quadratic viscous loss terms associated with high Reynolds number flow. The MREA model was then integrated with the BLPM and seat suspension model. The optimal control objective was to ensure that the suspension system came to rest with no end-stop impact after utilizing the available stroke, that is, a soft landing criterion. The simulated responses under optimal control were analyzed for optimal MREA loads for a 90th percentile male occupant at sink rates ranging from 5-10 m/s. As assessment of the pelvic injury criteria demonstrated that the MREA-based seat suspension system was able to maintain a desired level of occupant protection over the simulated sink rate range, unlike a fixed load-stroke energy absorber which can be optimally tuned for only a single sink rate. In addition, because the MREA was able to adapt the stroking load for different sink rates, injury criteria associated with upper torso, viscera and head were not violated even for minor injury levels for the stated sink rate range of 510 m/s.


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    Title :

    Biodynamic response mitigation for seat suspension with adaptive energy absorbers


    Additional title:

    Biodynamische Reaktionsabschwächung für Sitzaufhängungen mit adaptiven Energieabsorbern


    Contributors:


    Publication date :

    2011


    Size :

    13 Seiten, 10 Bilder, 4 Tabellen, 31 Quellen



    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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    Singh, H. / Wereley, N. / AHS International | British Library Conference Proceedings | 2011


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    Choi, Y.-T. / Wereley, N. M. / American Helicopter Society | British Library Conference Proceedings | 2003




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