Study On Mechanism And Protection Of Motorcycle Driver's Craniocerebral Injury Based On Typical Traffic Accident Reproduction

With the development of Chinese economy,motorcycle accidents have become an increasingly serious problem on road traffic safety,in which the driver's head usually suffers severe or even fatal injury.As the main protective device,the helmet motorcycle drivers wearing plays a vital role in protecting them from motorcycle accidents.Therefore,it is of great significance to study motorcycle drivers' head injury mechanism and the optimization of motorcycle helmet.Due to the ethical and experimental costs,it's difficult to conduct a specific research on head injury biomechanics.However,with the development of computer manikins,it is possible to study human injury mechanism by combining computer simulation with real traffic accidents.This paper,based on real traffic accidents,effectively improves the accuracy and reliability of research on crush injury by using the multi-rigid body system and finite element analysis method.The specific research methods and results are as follows:Firstly,this paper conducts a in-depth accidents investigation on road traffic in Chongqing,and mainly analyses the environment,vehicles,and the casualties of accidents.Then,based on the former investigation,the paper establishes an accurate vehicle multi-rigid body model,reconstructs the case accidents,and gets the dynamic response of motorcycle drivers by selecting 10 typical cases of motorcycle-car accidents with a video image.After that,the result accuracy of accidents reconstruction is verified through the head injury criterion and video image,at the same time,the correlation analysis of the factors affecting the head injury of the motorcycle driver is carried out.The results show that the speed of head clash is related to the traveling speed of the car in the side collision accidents,while in the oblique collision accidents,the speed of head clash is related to the traveling speed of the motorcycle.Secondly,on the condition of reconstruction result of milti-rigid-body accidents,the process of craniocerebral injury is reconstructed by using the THUMS(Total Human Model for Safety)4.0 cranial finite element model and the windshield finite element model.At the same time,the risk of injury is analyzed by extracting biomechanical damage parameters such as skull equivalent stress,craniotomy equivalent stress,intracranial pressure and maximal principal strain of brain tissue combined with the corresponding human tolerance limit value,which is compared to the brain injury in actual accidents.The results show that the reconstruction results of craniocerebral injuryare consistent with those in the real accidents and that the cranial fractures are likely to occur when the skull equivalent stress is more than 42 MPa,and severe brain damage may occur when the cranioceum equivalent stress is more than 24 kPa or the maximal principal strain of brain tissue is more than 0.1.Finally,the finite element model of helmet is constructed based on the real helmet,the helmet-cranial finite element model is simulated combined the THUMS craniotomy model with the car windshield model,and the helmet protection ability and protection effectiveness is studied by using the head injury parameters as the evaluation index.Then,orthogonal experimental design method is used to optimize the parameters of helmet shell and lining material with the aim of minimizing brain injury parameters.The results show that the optimized helmet significantly reduces the head damage parameters and improves the helmet protection efficiency,which can effectively reduce the risk of motorcycle drivers' head injury.