| With the surge in vehicle ownership,the safety of pedestrian collisions has become increasingly prominent.In the process of ensuring the safety of pedestrian travel,pedestrian injury research plays an indispensable role.In pedestrian safety field,head injury has always been a hot topic for scholars.Although there have been a lot of studies on pedestrian head injury,this paper finds that there are still some limitations in the current pedestrian regulations and related researches through the studying of pedestrian regulations and related literature.These limitations mainly include:the subsystem tests can't efficiently reflect the real injury risk of the pedestrian's head and the existed pedestrian numerical models can't balance the calculation efficiency and simulation accuracy.In view of these limitations,a new Coupled Pedestrian Computational Biomechanics Model(CPCBM)is established by the coupling technique.The model's reliability was verified via three published cadaver-buck collision tests and a real pedestrian traffic accident.In this study,the kinematic response differences between the CPCBM model and the subjects in the experiment or accident were compared,and the correlation between the simulation and experimental signals were evaluated by a quantitative correlation evaluation method-Correlation and Analysis(CORA).The results show that the CPCBM model and the TNO model(developed by The Netherlands Organization)have similar ability to predict human head motion response during the cadaver tests and accident.Meanwhile,the CPCBM model can predict the brain injury that is not available for the TNO model.Then,the method that prescribed a head model collision boundary conditions(prescribed collision boundaries)and the method that prescribed a head model motion curves(prescribed motion trajectories)are used to reconstruct a pedestrian head injury in a real accident respectively,and the predicting results were compared with the CPCBM model.According to the information recorded in the accident,the head injuries predicted by the CPCBM model are consistent with the pedestrian suffered in the traffic accident.Compared with the CPCBM model,the head injuries predicted by the prescribed collision boundaries method show that the predicted head injury severity is much lower,and this method cannot predict the cumulative injuries caused by the vehicle and ground;the results predicted by the prescribed motion trajectories method are lightly smaller than the CPCBM model,but this method assumes the head model skull rigid,which is not capable of predicting a pedestrian's skull fracture as in the CPCBM model.Finally,after the reliability of the CPCBM model was verified,this paper applied the PCBM model to study the relationship between the windshield angle of small passenger cars and pedestrian brain injury.The results show that the front windshield angle has a significant impact on the head injury during pedestrian collision,and the influence is related to the collision position of pedestrians and vehicles.According the head injury criteria used in this paper,When the windshield inclination angle increment from 24°to 50°,the severity of the head injury will decrease first and then increase;when the pedestrian strikes the front end of the bumper 1/2,the severity of the head injury is generally higher than the collision position at the front end of the bumper 1/3.In summary,the CPCBM model is a pedestrian model that takes both computational efficiency and head biofidelity into consideration,which can be used not only for the study of pedestrian head first collision injuries(head and vehicle),but also provides a new research protocol for the study of head secondary collision(head and ground). |
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