Scaling head-neck response data and derivation of 5th percentile female side-impact dummy head-neck response requirements in NBDL test conditions

Abstract

The head-neck biofidelity of side-impact dummies can be assessed according to the response requirements for the head-neck system based on mid-size male human subjects as published in ISO TR9790. These criteria are largely based on volunteer tests performed at the Naval Biodynamics Laboratory (NBDL) in New Orleans. The first objective of this study is to provide a judgement on the validity of applying the scaling method developed by Irwin, Mertz, Ali, Elhagediab and Moss [Guidelines for assessing the biofidelity of side impact dummies of various sizes and ages. Stapp Car Crash J. 46 (2002)] to the head-neck system. The second objective is to develop additional scaling rules to supplement the rules developed by Irwin et al. (2002), in case the existing scaling method is not valid. In order to come to a judgement on the validity of applying Irwin et al.'s scaling method to the head-neck kinematics and dynamics, first a review was performed on Irwin's scaling method, gender related differences, and the head-neck anthropometry versus responses of the NBDL volunteers. On the basis of the review an analysis was performed to find scaling rules for the head-neck kinematics and dynamics that are most plausible. From this study it was concluded that the scaling method developed by Irwin et al. to scale the mid-size male response requirements for the NBDL test condition (ISO TR9790 Neck Test 1) to a small female is only valid for the T1 lateral displacement, but not for the other response requirements. The scale factors that were found to be invalid were updated using relationships found in literature on head-neck biomechanics, and relationships found in the NBDL volunteer analysis.

Keywords:

• response scaling
• head-neck biomechanics
• 5th percentile female
• side impact
• side-impact dummy
• head-neck response requirements

Notes

∗Occiput-C7 spinous process;

∗∗Height was defined as the length of chord of cervical lordosis;

∗∗∗Length was defined as the length of arc of cervical lordosis arc.

∗ Note that the scale factor for the total body mass is similar to that of the torso mass, see Table 1.