Optimization Analysis Of Lower Leg Pedestrian Protection Based On A Car Model

During the collision with a car,the lower leg of pedestrian is one of the most vulnerable parts which would cause serious injury.Some of these injuries might be irreversible and will accompany the pedestrian a whole life.Therefore,abounded attention focused on the protection of the pedestrian lower leg in recent years.Automotive companies also take the problem of pedestrian lower leg protection seriously.Appropriate design of the vehicle front structure plays a vital role in protecting the pedestrian lower leg.In the design and development process of a new type of car,the rationality of the design of the front impact energy absorbing structure is an important factor for the evaluation of pedestrian lower leg protection.In this paper,the development and regulation of pedestrian collision protection were seriously investigated.The basic principle of vehicle collision is described based on the related finite element theories.The problem of vehicle and pedestrian collision is also studied in the preliminary development and design of a new type of Brilliance car.The finite element model of vehicle pedestrian collision was established.The process of CAD model geometric cleaning,and geometry simplification,and the choice of CAE elements were discussed in detail.The process of material constitutive model selection,and model simplification,and initial conditions and simplification of the boundary conditions were also described.Based on the domestic regulation GB/T 24550-2009,the boundary conditions were set and solved by using LS-DYNA.Based on the numerical results,this paper analyzed the deformation damage value of the leg by means of the maximum dynamic knee bending angle,the maximum dynamic knee shearing displacement,maximum tibial acceleration,and deformation of the leg.This paper made a detailed analysis of the items that do not meet the requirements of GB/T 24550-2009,and the optimization scheme was given.By increasing the width of the vehicle front bumper,and increasing the width of the energy absorbing foam,and weakening the bracket in the structure,and adding the lower leg support structure,the leg bending deformation was much more reasonable and the damage from the car was reduced.The similar analysis was carried using the optimized model.The bending angle of the knee,the knee shear displacement,tibia acceleration has improved significantly.The numerical results meet the requirements of the domestic regulations.The real vehicle crash test was carried out.The results of the structural deformation and the deformation of the leg were compared with those of the previous numerical simulation.The results show that the numerical results were agreed well with the experimental results.The variation trend,the peak value and the time of the simulation curve were smaller than the experimental curve.The numerical analysis and experiments carried out in this investigation improved the modeling method of pedestrian protection of the existed model of Brilliance auto.The calculation precision of the model was also improved.At the same time,this paper puts forward the design method of vehicle front end structure,as well as the focus of attention from the perspective of Pedestrian Leg protection.The investigation of this paper could help the designer to avoid extra optimization works and shorten the project development cycle.The results of this paper can be used as reference for the development of pedestrian leg protection.