# A Female Multi-Body Head-and-Neck Model and Validation for Rear Impact Simulations
###### Abstract
This model was improved for frontal and lateral impacts. [PERSON] et al. [15] developed this model further for rear-end impacts. [PERSON] [16] built a computational male dummy for rear impacts; this model was validated against volunteer data and used in the development of the BioRID dummy. Muscle substitutes with tuned elastic stiffness and damping properties provided better responses. [PERSON] [3] designed a biofidelic 50 th percentile male multi-body head-neck model to be used in rear impact simulations, and this model was verified successfully using volunteer data. The head-neck models have been developed mostly for the 50 th percentile male in crash safety studies. Even though women are more vulnerable to soft tissue injuries to the cervical spine, no comparable modeling efforts have been addressed for females until the start of the ADSEAT project [17] about 15 years ago. The injury risk is a serious concern for women. Females are susceptible to higher injury risk and they have higher injury risk in all categories, except mortal injuries [18]. Recent research indicates that females aged between 20 and 30 are more prone to die in comparison to males in the same age range in road traffic accidents [19]. Furthermore, the risk of calamitous injury was found to be 22 percent higher for women, based on the Fatality Analysis Reporting System database [20]. Gender is one of the important risk factors for whiplash-associated disorders. Researchers indicate that females are at a significantly higher risk of sustaining whiplash compared to males, even under similar crash conditions, and these studies also reveal that the risk for females is three times that of males in equivalent conditions [17; 18]. The differences in the morphology of the head-neck complex between females and males could explain the higher risk of whiplash for females. The neck anthropometry is the most significant difference between genders. Studies have shown that females have weaker neck muscles, and the reflexes of the muscles are faster [18]. Furthermore, females generally have smaller necks and vertebral body sizes with respect to their head size in comparison to males. According to the [PERSON] et al. study [21], due to the larger vertebral dimensions, males have better intervertebral coupling stability. Females show a greater range of extension-flexion motion. Also, dynamic tests have revealed a more prominent S-shaped curve in the female neck in comparison to males [17]. A finite element dummy model for an average female (50 th percentile female) was developed 10 years ago for better protection of females in rear impacts [22; 23]. Crash test dummies were designed to set out for the variation in stature and weight of the population. The hybrid III 50 th percentile male, the 95 th percentile male, and the 5 th percentile female are used in frontal impact tests. Based on [PERSON] et al. study [24], the height and mass of the 5 th percentile female are 151.1 cm and 47.3 kg, respectively. This mass and stature are similar to those of a 12-year-old girl in the Swedish population [18]. To address the gender problem, the first rear impact computational dummy for an average female has been developed [22]. [PERSON] et al. [22] developed a finite element model of the 50 th percentile female dummy for rear impacts which is called EvaRID and this is the first female dummy to be used in rear impact simulations. EvaRID is based on literature data and scaled from the average male rear impact dummy, the BioRID II dummy. The physical properties of the female dummy were based on literature data as well. The mass and stature of EvaRID was set as 62.3 kg and 161.8 cm, respectively [22]. The mechanical properties of the neck (i.e., damping and stiffness) were scaled to 70% of those of the BioRID II dummy as an initial estimate. In EvaRID, the masses of the body segments were determined using uniform density approximation. This dummy is valuable, but some updates, such as joint stiffness, were necessary considering its responses in the validation tests. [PERSON] et al.