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Mertz

Overview​

The Mertz scaling method, developed by H.J. Mertz, is used to normalize injury thresholds across different body sizes and populations [1]. These thresholds, derived from cadaver data, are scaled to apply to crash test dummies of various sizes [1]. In the tables below, the Mertz scaling method was applied to generate neck injury criteria (Nij intercept values) for subjects ranging from a 6-month-old infant to a large adult male [2].

Required Signals​

  • Forward/Rear Force of Neck (N) (X)
  • Tension/Compression Force of Neck (N) (Z)
  • Flexion/Extension Moment of Neck (N-m) (Y)

Calculation​

  1. Filter force (CFC = 1000) or moment (CFC = 600)
  2. Computer IARV using comparison curve

Injury Criteria​

Neck Injury Tension Injury Assessment Reference Curve - In-Position​

Neck_Axial_In_Position

Neck_Axial_In_Position

Neck Axial Force Injury Criteria - In Position [2]

Neck Injury Tension Assessment Reference Curve - Out-of-Position​

Neck_Axial_Out_Position

Neck_Axial_Out_Position

Neck Axial Force Injury Criteria - Out of Position [2]

Neck Injury Compression Reference Curve​

Neck_Compression

Neck_Compression

Neck Compression Force Injury Criteria [2]

Neck Injury Shear Reference Curve​

Neck_Shear

Neck_Shear

Neck Shear Force Injury Criteria [2]

Neck Injury Flexion-Extension Reference Table - In-Position​

Neck_Flexion_Extension_In_Position

Neck Flexion and Extension In-Position Injury Criteria [2]

Neck Injury Flexion-Extension Reference Table - Out-of-Position​

Neck_Flexion_Extension_Out_Position

Neck Flexion and Extension Out-of-Position Injury Criteria [2]

In position testing refers to crash testing where the ATD is properly seated and restrained, similar to a typical driving scenario [3]. Out of position testing refers to crash testing where the ATD may be in a non-seated posture or have shifted from their seat [3].

References​

[1] Mertz, H.J., Irwin, A.L., & Prasad, P. (2003). Biomechanical and scaling bases for frontal and side impact injury assessment reference values. Stapp Car Crash Journal, Vol. 47.

[2] Mertz, Harold J. "Anthropomorphic test devices." Accidental injury: Biomechanics and prevention. New York, NY: Springer New York, 1993. 66-84.

[3] "Guidelines for Using the UMTRI ATD Positioning for ATD and Seat Positioning (Version I)". Insurance Institute for Highway Safety, January 2003.