| The frontal pole impact is one of car-to-obstacle crash scenarios, and it is very different from other scenarios of crashes. Although the accident rate of the pole impact is relatively small, it suffered heavy losses. Nowadays, there is a gap of domestic researches in this field. The existing CNCAP and mandatory regulations have not yet established for the frontal pole impact. Therefore, it is necessary to do research on the frontal pole impact, which is of great significance to enhance the crashworthiness of vehicle frontal structure.This paper intends to make an investigation of the vehicle structural crashworthiness and crash characteristics, as well as a parametric study of occupant injuries in frontal pole impact. Furthermore, the approaches were explored to improve vehicle front structural crashworthiness.On the basis of a literature study, three methods were summarized for enhancing of vehicle structural crashworthiness and the small overlap impact regulations were introduced. A finite element model of a commercially available car was developed, and the frontal crash test and the frontal offset crash test data were used for validation of the model. A comparative study of40%offset crash and pole impact was conducted based on the C-NCAP regulations. A pole impact model was then developed with three different impact regions of15%,25%and50%. Furthermore, a comparative analysis was carried out in terms of the crash characteristic of frontal pole impact with different crash regions. Frontal pole impact has the characteristics of bigger peak acceleration, which take place earlier with shorter duration compared with offset crash. The intrusion of firewall and the displacement of the A-pillar have each increased by162mm and140mm, respectively. The50%pole impact has the highest acceleration in three different crash zones, while25%pole impact has the minimum peak acceleration, the rating of structural crashworthiness of the three pole impacts were "POOR","MARGINAL" and "ACCEPTABLE", respectively.In the end, the force transmission paths of three different crash regional pole impacts were analyzed and the three methods to enhance the vehicle structure crashworthiness were explored. The body structure was reasonably improved and optimized based on the characteristics of the frontal pole impact. The rating of structural crashworthiness of the15%,25%and50%pole impacts was upgraded to "MARGINAL’"ACCEPTABLE" and "ACCEPTABLE" for the improved structure. The passenger compartment stiffness and peak acceleration were also increased. The MADYMO program was used to establish a model of the frontal pole impact. Occupant injury protection model and studied the A parametric study of occupant injury was conducted by using the MADYMO model.The results show that the frontal pole impact possesses properties of smaller crash area, bigger and concentrated impact force, causing serious damage to the vehicle structure, greater peak acceleration and more intense curve fluctuations, comparing with the results from the frontal offset impact. The three frontal pole impact with different crash areas of15%,25%and50%, the deformation of15%frontal pole impact on the front-end’s structure is smallest but most serious. For the50%pole impact of front-end, the deformation is bigger than others and the damage to the passenger compartment is less. The acceleration is the greatest. By increasing the thickness of the component, using super steel, adding structural parts to increase the stiffness of passenger compartment. The crashworthiness of frontal pole impact can effectively enhanced by optimizing of the force transmission path, improving the structure of front-end and increasing the energy-absorbing parts. It was noticed that the peak acceleration will be increased in case increased stiffness. Frontal pole impact has small effect on the upper body parts, such as head, chest and neck, however, it is high risk of injury to the legs. |
PDF Full Text Request