EvaRID: A 50th Percentile Female Rear Impact Dummy FE Model

Journal article, 2011

Introduction: Vehicle crashes causing ‘whiplash injuries’, is of great concern worldwide. These injuries occur at relatively low velocity changes (Δv), typically < 25 km/h, and in impacts from all directions. Rear impacts are, however, associated with the highest risk and the highest frequency. A number of studies have shown that the whiplash injury risk is higher for females than for males, even in similar crash conditions. Yet, there is only one size of rear impact crash test dummy available – the 50th percentile male (BioRID or RID3D). It does not represent females in terms of mass distribution and dynamic response, and the size corresponds to a ~90th–95th percentile female. Consequently, the existing whiplash protection concepts are more effective for males than females, with 60% risk reduction of permanent medical impairment for males compared to 45% for females. The objective of this study was to start addressing this shortcoming by developing a finite element model of a 50th percentile female rear impact crash dummy, ‘EvaRID’. Materials and Methods: To establish anthropometric specifications of the 50th percentile female, several sources were assessed, such as anthropometric data from different countries and review of previous publications from the development of the other dummy sizes. The EvaRID V1.0 model was obtained by scaling an existing BioRID II LS-DYNA model. Mass and geometrical dimensions were scaled to obtain values representative of the 50th percentile female. Width and depth dimensions were then established based on scaling of each body segment. Stiffness and damping properties of materials and discrete elements were kept in accordance with the BioRID II model. The EvaRID V1.0 model was evaluated with regard to rear impact tests with female volunteers at Δv 7 km/h, Carlsson et al. (1). The volunteers were selected based on their stature and mass being close to the 50th percentile female. Parts of this work have been published in more detail, Chang et al. (2). Results and Conclusions: Until ~250 ms, good correlations were found between the EvaRID V1.0 model and the volunteer tests for head and T1 accelerations and x-displacements, and head angular displacements. The EvaRID model showed markedly less angular motion of the upper thoracic spine in extension compared to the female volunteers. To improve this it will be necessary to adjust the stiffness of the spinal joints. In the future, the EvaRID dummy model has the potential to become a valuable tool when evaluating seats and whiplash protection systems. It may potentially be used as a template for the development of a physical female size dummy. Acknowledgements: This study is part of the ADSEAT project, European Commission, ID 233904. Additional funding was received from the Swedish Transport Agency. References 1. Carlsson A, Linder A, Svensson MY, Davidsson J, Schick S, Horion S, Hell W. Female volunteer motion in rear impact sled tests in comparison to results from earlier male volunteer tests. (2008): Publ ID 88835, http:// publications.lib.chalmers.se/cpl/ 2. Chang F, CarlssonA, Lemmen P, Svensson MY, Davidsson J, Schmitt K-U, et al. EvaRID: a dummy model representing females in rear end impacts. (2010): Publ ID 128706, http://publications.lib.chalmers.se/cpl/