Research On Driver KTH Injury In Frontal Impact Based On Lower Extremity Model With 3D Active Muscles

According to statistics,71%of lower extremity injuries occurred in vehicle frontal crashes,which Knee-Thigh-Hip(KTH)injuries accounted for about half.At present,based on the previous rigid pendulum knee axial impact experimental study,the definition of the femoral axial force 10kN for the national crash safety regulations KTH injure indicators has been widely questioned.In addition,the traffic accident statistics show that the real situation of lower extremity injury and early cadavers test results do not match.Recent studies have proposed two hypotheses as a basis for further exploration:the effect of active muscle force,and the combined effect of axial force and bending moment.The aim of this research was to investigate the effect of active muscle force on the mechanism and tolerance of the lower limb of the driver in frontal impact,and to explore the changes of the indicators value of the femoral/tibial axial force and bending moment under the action of muscle force.Firstly,based on the calf skeleton model and muscle MRI data,a 3D active block muscle lower limb-pelvic finite element model was established based on the muscle simulation method of ID beam element and 3D solid element coupling.Then,through the cadavers experiment to verify the model under the impact load of the passive response.Further,based on the volunteer gait experiment and volunteer emergency braking experiment,the response characteristics of the model under active muscle force were verified.The reliability of the biomechanical response of the fully validated model in the state of without activation and activation of the muscle.After verification,coupled 50%of the Hybrid III dummy upper body model with the lower limb model to establish a hybrid dummy model,combined with the cockpit and constrained system to establish the crash injure analysis of the driver-constraint system model.Finally,considering the characteristics of three typical overlap rates(100%,40%,25%)in frontal impacts,the vehicle acceleration and intrusion curve were extracted respectively,and the real frontal crashes loading environment was established by combining the muscle activation curve of the emergency brake experiment.At the same time,the dynamic response and damage characteristics of the driver without muscle activity were analyzed,compared with the former to explore the axial force,bending moment and other indicators of the difference,the influence of the muscular force on the injury of lower limb was observed by the driver’s evasive maneuvers behaviors.The results showed that the active contraction of the muscles in the lower limbs of the driver would significantly increase the axial force,bending moment and stress value of the femur and tibia,the increase was related to the activation level,and the injury position was consistent with the traffic accident statistics,the total number of fractures is more than that of the no-activation model,and the injure difference of the accident statistics and the cadavers experiment is explained to a certain extent.The femoral injury in KTH is related to the combined effect of axial force and bending,such as femoral fractures under axial force of 5.97kN and bending moment 175.3N·m under active muscle force in 25%bias frontal collisions.In addition,the vehicle crash acceleration allows the driver to produce inertial force on the lower limb injury have a greater effect,a huge amount of interior invasion increased femoral and ankle injury risk.This above results provide a reference for the improvement of vehicle crash safety regulations and the design of automobile safety.