Research On The Front Structure Of An SUV Based On Frontal 25% Offset Collision

In the urban traffic environment,the probability of small offset collision accidents is high,and the energy-absorbing components in the small offset collision cannot give full play to the energy absorption effect.This leads to serious deformation of the passenger compartment structure in the collision,the safety of the occupants will be greatly threatened,and with the improvement of people’s demand for travel comfort,SUV models have become one of the mainstream models in the city.So this thesis studies the front-end structure of an SUV body in a frontal 25% offset collision.The main research contents of this thesis are as follows:Firstly,the finite element model of the whole vehicle is established by Hyper Mesh software,and the parameters are calculated according to the C-IASI frontal 25% offset crash test protocol.The k file is submitted to LS-DYNA software for calculation,and the simulation results show that the energy conversion during the collision process is good,the proportion of hourglass energy in the total energy of the system after the collision is about 2.58%,the ratio of the increased mass to the total mass of the vehicle model is 0.738%,the mass increase percentage is far less than 5%of the total mass of the vehicle model,and the hourglass energy and mass increase meet the reliability requirements,proving that the established model is accurate and reliable.Secondly,the key parameters in the collision process are analyzed,such as: vehicle displacement deformation,door frame deformation,A-pillar bending deformation,B-pillar acceleration,front apron intrusion,etc.Through the analysis,it is found that the body will be deflected at a certain angle around the barrier during the collision,the acceleration of the B-pillar is too large,the occupant’s head may be greatly injured,the upper and lower hinges of the Apillar and the threshold beam are seriously deformed,resulting in a large number of occupant safety space is compressed,according to the C-IASI regulations to rate the crashworthiness of the body structure,the rating result is "poor".Based on the above analysis,the problems of the body structure are summarized.Then,through the analysis of the collision force transmission path and the collapse area of the front compartment of the engine,corresponding improvement schemes are proposed for different energy-absorbing components at the front end of the body: appropriately extend the anticollision beam,add a force transmission structure between the anti-collision beam and the front side beam,open a collapse guide groove on the upper side beam of the engine compartment,add a reinforcement plate in the bending area of the A-pillar and the threshold beam,and increase the thickness of the upper side beam of the engine compartment,the inner and outer plates of the Apillar,and the front enclosure plate to increase the thickness and replace the material to improve its strength.The improved vehicle model was submitted for calculation again,and the key parameters were analyzed,the energy absorption of the front side beam structure was increased to 28 k J,the peak acceleration of the B-pillar X direction was reduced by 53.4%,the peak acceleration of the B-pillar Y direction was reduced by 43.7%,the intrusion position of the front fence was shifted from the lower left area to the steering column area,the intrusion amount was reduced by 89.5mm,the deformation of the door frame was greatly improved,and the crashworthiness of the body structure was improved from "poor" to "excellent".Finally,through comparative analysis,it is proved that the crashworthiness of the improved body under the collision condition of 100% rigid barrier on the front has also been improved,indicating that the analysis and improvement in this thesis have certain universality.