Neck Moment Characterization of Restrained Child Occupant at Realistic Nontest Standard Higher Impact Speed of 32.2？km/h

The effects of bullet vehicle crash impact angle, child restraint system design, and restraint harness slack at side impact speed of 32.2？km/h (20？mph) on moments sustained at the neck by a three-year-old child are investigated. Mathematical models are built using the response surface method based on simulation results whereby good fitness is achieved. The singular and cross interactive effect of each predictor on the neck moment are analyzed. The number of significant parameters affecting the neck moment is shown to be the largest for wide impact angles and the impact angle parameter is largely revealed to be the most sensitive. An ideal safe range for low neck moment has been established to be within angles 45° and 65°. It is further shown that the nature of all parameters effect on the neck moment is highly dependent on the impact angle range. 1. Introduction It has been shown over the last two decades that vehicle crashes have become the leading cause of death for children in many developed countries [1–4]. The side impact crash mode especially is shown to be a particularly harmful mode [5, 6]. Many factors contribute to this scenario, one of which is the presence of shoulder harness slack [3, 6, 7]. Another is due to the kinematics of side impact crash which depends upon both the magnitude of the impulse from the bullet vehicle and its principle direction of force (PDOF) impacting angle [8]. In addition, it has been shown that the head contact with intruding door due to the bullet vehicle plays a pivotal role and has to be considered in addressing any mitigation efforts [9, 10]. Although head injuries are largely reported to be prime cause of fatalities in child restraint system (CRS) restrained toddlers involved in side impact crash [3, 4, 10, 11], there is sufficient cause for concern where the fatality may also be related to high neck loading [12]. Investigation of neck moments pertaining to CRS design, misuse, and crash parameters is yet unexplored due to insufficient accident data and costly full vehicle analysis simulations. Thus, the effects and relationships between the singular and cross interactive parameters, especially for oblique side impact involving intrusion, are not studied [10]. Insights obtained from such a work would serve to promote better understanding of the side impact crash event in order to achieve greater injury mitigation. In this work, a study is undertaken to characterize the neck moment (NM) of a CRS restrained 3-year-old child occupant involved in lateral and oblique side impact, with respect to identified relevant