Research On Head Response And Injury Protection Of Cyclists Based On An Efficient And Stable Human Body Finite Element Model

At present,helmet is considered to be the most effective means to protect cyclists from head injury,but the high risk of head injury under helmet protection in real accidents indicates that the existing helmet design still needs to be further improved.At the same time,human body numerical model has become an important tool for the research of cyclists’ injury and protection in vehicle collision.However,the existing human body finite element model is difficult to have both computational timeliness,simulation stability and biological fidelity,which restricts the further development of cyclists’ head injury and protection research.Therefore,based on the establishment of a human body finite element model with computational timeliness,simulation stability and biological fidelity,this paper deeply studies the head response characteristics of two wheeled cyclists in vehicle collision,and then puts forward a new helmet design to meet the requirements of protection performance and lightweight,so as to provide theoretical basis and technical support for the safety protection of two wheeled cyclists.The first step is to establish and verify an efficient and stable finite element model of human body.Firstly,the feasibility of using hollow structure to simulate the impact mechanical properties of human solid tissue is proposed and proved.Then,this modeling method is used to simplify the refined THUMS model,establish the whole person finite element model with hollowed out skin tissue(named THUMS-HS model),and verify the biological fidelity of thums-hs model through the cadaver experimental data in the literature and real accident human injury.Finally,compared with the original THUMS model,it is proved that the THUMS-HS model has high computational timeliness and simulation stability.The results show that the dynamic responses of parts and whole body of the THUMS-HS model are close to the experimental data of cadavers,which can accurately predict the risk of human injury in real vehicle collision accidents.The computational timeliness is nearly 2/3higher than that of the original THUMS model,and has high simulation stability in highenergy collisions.The second step is to study the head response of cyclists in vehicle collision.Firstly,the finite element models of two wheeled vehicle and EPS helmet are established.Based on the above-mentioned high-efficiency and high stability human body finite element model,the vehicle two wheeled vehicle cyclist collision simulation analysis with or without helmet protection is carried out.This paper studies the overall kinematic response,head dynamic response and biomechanical response characteristics of two wheeled cyclists in vehicle collision,and analyzes the potential injury factors of cyclists’ head under vehicle collision load and the protective performance of traditional EPS helmets.The results show that the collision between cyclist head and vehicle can cause high strain and pressure in brain tissue,wearing traditional EPS helmet can reduce the maximum strain of brain tissue,but it may increase cyclist head collision speed and increase intracranial pressure in head.The third step is to study the design and protection performance of airbag helmets.Firstly,the design method of airbag helmets is proposed,the finite element model of airbag helmets is established,and the airbag pressure is determined based on the compression deformation of helmet lining.Then,combined with the regulatory drop impact test conditions and vehicle rider collision conditions,the head injury dynamics and biomechanical evaluation indexes are used to evaluate the protective performance of airbag helmets,and the protective performance differences between airbag helmets and traditional EPS helmets are compared and analyzed to reveal the protective mechanism of airbag helmets.The results show that the airbag helmet designed in this paper can reduce the mass by about 30% compared with the original EPS helmet,and has good protective performance.The risk of skull fracture and moderate brain injury of cyclists are controlled below 25% and 35% respectively.