Abstract:

To optimize vehicle design and improve road safety, the effect of the NBLEH on pedestrians head injuries during ground contact was investigated. The impact with the ground AIS 1+ pedestrian landing injury cases was selected, and data analysis along with multicollinearity tests was conducted. The results show that as the NBLEH increases, the severity of pedestrian head injuries exhibits a corresponding upward trend. Through Logistic regression analysis, it is further revealed that for AIS 2+ head injuries in adult pedestrians can be jointly predicted by vehicle speed, age, and NBLEH. Specifically, the risk of injuries is increased with higher values of NBLEH, faster speeds, and older ages. Analysis of real accident videos demonstrates that a smaller NBLEH results in increased full-body rotation angles of pedestrians. However, once NBLEH surpasses 0.9, the rotation angle notably diminishes. The collision force transmission and the pedestrian's landing posture are altered by different values of NBLEH. Additionally, cadaver crash tests were conducted using two types of vehicles with different front-end heights to establish test conditions with different NBLEH values. The results indicate that NBLEH not only influences the timing of head contact with the ground, but also that there is an interaction between head landing posture and collision speed, further complicating head injuries. Parametric simulation studies reinforced that NBLEH significantly influences factors such as posture, angle, timing, and speed during pedestrian head-to-ground contact, thereby increasing the complexity and uncertainty of surrounding injury mechanisms. The simulation results show that both vehicle speed and NBLEH influence the pedestrian flip angle, with NBLEH values less than 1 producing larger pedestrian flip angles than values greater than 1.

Key words: normalized bonnet leading edge height (NBLEH), pedestrian strucks, pedestrian-ground contact injuries, abbreviated injury scale (AIS), road traffic, head injury