A Comparison Analysis Of The Simulation And Protection Effect Of The Driver's Knee And Pelvic Airbags In A Frontal Collision

The frequent occurrence of vehicle traffic accidents makes it a major social responsibility to improve vehicle safety performance.In all kinds of collision accidents,the ratio of frontal collision is 62%,which is the focus of automobile safety.However,in the past years of frontal collision,the main driver's head and chest,which are two important protective parts,have been deducted,especially the chest.It is indicated that there is still a great risk of injury to the dummy's head and chest under the protection of the driver airbag(DAB).The safety of the driving side restraint system needs to be further improved.At present,in the related research,it is found that in the frontal collision,the knee airbag(KAB)and the hip airbag(HAB)have positive effect on the improvement of the driver's upper body protection,but the driver's chest score still has a significant space for increase.The reduction of chest compression is a major problem in the improvement of the protection effect of the driver's side restraint system.Therefore,this paper uses the combination of simulation and test to combine the KAB with the HAB to carry out the comparative study on the protective effect of the chest and other parts.Firstly,in this paper,the finite element theory,the multi-rigid-body theory,the theory of gas thermodynamic and the inflation and contact algorithm of the air bag are described.Based on the MADYMO software,the inflatable expansion model of the air bag is established by the uniform pressure method.The air bag is folded and provided with various parameters such as fabric material,generator gas component,mass flow and temperature flow.In order to ensure the reliability of the model,the static expansion test and the linear impact test are made to obtain video and stiffness curve of the air bag,so we can verify the characteristics of the air bag unfolding package type and the internal pressure.Then,the model of the main driving front restraint system is established,which comprises a vehicle body finite element model and a multi-rigid body model,and the finite element model acts as a localizer for multi-rigid body model.After this,the acceleration waveform of the real vehicle collision test is input into the constraint system model,and the collision simulation is carried out to obtain the dummy movement posture and response curves of each part,and the reliability of the constraint system model is verified by using the test data as the standard.At the same time,as the basic data of the restraint system protection effect under the condition of not installing KAB and HAB,it is found that only under the effect of DAB,the head HIC36 is 649 and has a risk of point deduction.At the same time,chest compression is reached to 33.7 mm,the chest score is 2.39 and the total score of the restriction system is 12.91.Finally,KAB and HAB are replaced into the positive restraint system,and the 100%rigid barrier collision is simulated.Contrast the dummy movement posture,and according to the injury index and scoring standard of C-NCAP,the comparative study of KAB and HAB in single action and joint action is developed from three aspects of response curve,damage value and final specific score of each part of the dummy,especially on the improvement of chest protection effect,which is expected to solve the problem of reducing chest compression and provide another possibility to improve the protection effect of driving restraint system.Next,other injuries of driver and the whole safety performance of driver side restraint system are analyzed comprehensively,which provides a data basis for further research work.It is found that the combined use of KAB and HAB could greatly reduce chest compression to 28.2mm,decreased by 16.32%,which makes the chest score close to 5 points.At the same time,head HIC36 is reduced to a minimum of 623,decreased by 4%and the constraint system gets the highest score of 13.71 to achieve the best protection effect.However,because of the limitation of vehicle space,the damage value of the right leg of the dummy is always greater than left leg,and it is easy to produce shear,which leads to the increase of knee slip,and the protective effect of the lower limbs of the dummy has not been improved.Later,we can adjust the height of KAB and perform the parameter optimization of KAB and HAB,so that the lower limb protection effect will be further improved,and the restraint system will have better protection effect.