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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
drawbacks?
Thank you very much.
Jinhua Guan, PhD
National Institute for Occupational Safety and Health
Morgantown, West Virginia
U.S.A.
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
drawbacks?
Thank you very much.
Jinhua Guan, PhD
National Institute for Occupational Safety and Health
Morgantown, West Virginia
U.S.A.