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Mertz Time-Dependent Loading Criteria

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  • Mertz Time-Dependent Loading Criteria

    In analyzing dummy responses, time-dependent loading is an important
    issue because the load that biological tissue can withstand prior to
    failure is time dependent. Mertz provided time-dependent loading curves
    for neck tension, neck compression, neck shear, and femur compression in
    his famous article "Anthropomorphic Test Devices". These curves express
    the relationship between loading and duration in the assessment of
    injury potential. For example, in assessing axial neck tension loading
    on a mid-size dummy (assuming 80 percent muscle tone), the critical
    loading values are 4170 N at 0 ms, 3665 N at 35 ms, 1390 N at 60 ms. The
    method to calculate the time-dependent loading is provided in SAE J1727.
    However, few published sled tests have applied these loading curves in
    the analysis of dummy responses. In fact, they simply ignored the Mertz
    curves and concentrated on Hij and other FVMSS-based criteria, which
    focus on peak axial force, peak shear and peak neck moment. Are there
    any reasons for not using the Mertz curves? Do Mertz curves have major

    Thank you very much.

    Jinhua Guan, PhD

    National Institute for Occupational Safety and Health

    Morgantown, West Virginia