# A Female Multi-Body Head-and-Neck Model and Validation for Rear Impact Simulations
###### Abstract
An experimental seat with a head restraint was utilized to compare the responses of BioRID P50F with those of the female volunteers. The spine stiffness of BioRID P50F is roughly 70% of that of the BioRID II dummy, though this scale varies between different parts of the dummy. The validation tests revealed that the BioRID P50F dummy needed more improvements to increase its biofidelity since there were significant differences between the kinematics of the dummy and the volunteers. Lately, the Seat Evaluation Tools (SET) [33] have been developed, which are the physical dummies for an average female and male (SET 50F and SET 50M, respectively) as a continuation of the ViVA and ViVA II projects. These physical dummies are designed to be used for rear impact testing. The design of BioRID II and BioRID P50F dummies are the basis of the average female prototype dummy SET 50F. The neck of SET 50F is composed of three vertebrae, allowing motion in the sagittal plane only, whereas the lumbar and thoracic spine designs allow motion in the lateral direction and in the sagittal plane together with axial rotation. The responses of SET 50F were compared to those of female volunteers by using volunteer data from an earlier study [34]. It was observed that the responses of the SET 50F dummy were out of the volunteer response corridors significantly regarding T1 angular displacement, head relative to T1 angular displacement, T1 x-displacement, and head relative to T1 x-displacement. The simpler neck design with three vertebrae could be improved together with a reassessment of the abdominal design of the dummy in order to achieve better agreement with the volunteer data. In light of the past and recent studies on female human-body and dummy models, it can be concluded that developing a female model requires a very long time (more than 15 years), and it is very hard to match model responses with those of the volunteers. The state-of-the-art female models for rear impact testing represent an average female (50 th percentile) only. Hence, it is required to extend the range of female models to cover other percentiles. Besides, the computational female models are finite element models only. Hence, a multi-body female model would be a good contribution to the literature since such a model would accelerate the development of seat and head restraint systems for the protection of females. Therefore, the main contribution of this research is the development of a computationally efficient 35 th percentile female multi-body head-neck model for the first time in the literature, which can be used as the head-neck section of a 35 th percentile female human-body model in rear impact simulations. The derived mechanical properties of the model obtained through calibration and validation provide a very useful and valuable dataset for the design of future female dummies. The presented literature review indicates that female models with higher biofidelity are required, and the female head-neck model developed in this study provides highly biofidelic responses. The model is validated successfully using the data from the Japan Automobile Research Institute, Tsukuba, Ibaraki, Japan (JARI) volunteer tests [29], which involved 35 th percentile female subjects. The female model presented in this study is thoroughly validated for the first time in the literature by using female volunteer data from rear impact tests with the highest severity (delta velocity of 10 km/h). This study is from the PhD thesis of the first author of this paper.