Several mathematical cervical models of the 50th percentile male have been developed and used for impact biomechanics research. However, for the 50th percentile female no similar modelling efforts have been made, despite females being subject to a higher risk of soft tissue neck injuries. This is a limitation for the development of automotive protective systems addressing Whiplash Associated Disorders (WADs), most commonly caused in rear impacts, as the risk for females sustaining WAD symptoms is double that of males. In this study, a finite element head and neck model of a 50th percentile female was validated in rear impacts. A previously validated ligamentous cervical spine model was complemented with a rigid body head, soft tissues and muscles. In both physiological flexion-extension motions and simulated rear impacts, the kinematic response at segment level was comparable to that of human subjects. Evaluation of ligament stress levels in simulations with varied initial cervical curvature revealed that if an individual assumes a more lordotic posture than the neutral, a higher risk of WAD might occur in rear impact. The female head and neck model, together with a kinematical whole body model which is under development, addresses a need for tools for assessment of automotive protection systems for the group which is at the highest risk to sustain WAD.

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Finite-element human body models (FE-HBMs) can be used to evaluate restraint systems by predicting thoracic injury. The biofidelity assessment of an FE-HBM Total HUman Model for Safety (THUMS) 50th percentile male occupant and the characterisation of its rib response to loads from frontal car crashes are the objectives of this study. The rib-cage mesh of THUMS version 3.0 was refined to improve the shoulder-belt interaction, material properties of lungs and skin modified, and the model biofidelity assessed against tests representative of frontal crashes. The modified THUMS response improved with respect to the baseline model. The modified THUMS was used to analyse the rib loading in frontal impacts. The rib response included shear, torsion and bending in belt and airbag-like load cases. This indicates that a criterion based only on rib anteroposterior compression may not be enough to predict fractures and that a criterion should consider compression, torsion and shear.

For the FE-Hybrid III, bar impacts caused higher chest deflection compared to hub impacts, although the contrary results were obtained with the more humanlike THUMS. Correction factors were developed that can be used to correct the Hybrid III chest responses. Higher injury criteria capping limits for steering wheel impacts are acceptable. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.