| 1.BackgroundThe structure of B-pillar is one of complex components and there are many parts which are need to fixed on it, just like front door lock striker, rear door hinge, some rids and there are many accessories, just like front seat safe belt and sometimes, various wiring harnesses need to be located through B- pillar. Besides, there is other most important function that it is relative with the life safe of occupant, is side impact bend crashworthiness. With regard to bend crashworthiness, B-pillar is not only received impact force directly, but also support roof panel and share the force with the front and rear door with inner board for them are supported on B-pillar in each one side. For having the ability to translate the force, most structures of B-pillars have convex radius too. So we know the importance of B-pillar and the target of this article is the research of the bend crashworthiness of B-pillar.2. Research wayIt is introduce the function complex of B-pillar on above and it lead to the structure complex of B-pillar from up to down. There are many changes, just like the changes of B-pillar thickness, the changes of width, the changes of convex radius, the changes of cross section, the changes of B-pillar lean degree and so on. So the research of single B-pillar is familiar, the research of different B-pillar is rare and especially, the most difficult is the compare of these pillars for they have different rules among them. It is important to have bend crashworthiness of these pillars to be compared.Firstly, article should simplify the complex structure of B-pillar. According to board bend worthiness research experience of Thinness Close-Hat Section Member, acquire the main structure parameter on B-pillar through simplifying the structure of B-pillar.Secondly, acquiring main structure parameters and using these parameters simplify structure of B-pillar and get six parameters to be researched and it is the width, thickness, flange width, lean degree and cross section angle of structure.3. Evaluation methodBecause there is not evaluation system about bend crashworthiness. Article need to custom relative methods to evaluate the quality of different B-pillar structure. Based on a lot of the domestic and alien papers, searching out the evaluation methods which were used in those articles for evaluate the bend crashworthiness usually. And furthermore, refer to regulation, which define evaluation method to occupant's hurt of different part of body and of different hurt degree, relative European and American side impact regulation. Finally, it isdetermined in this article that to choose max displacement and velocity of B-pillar, which is the base of European side impact regulation, to be the evaluation parameters for bend crashworthiness.4. Software used in ResearchThe content of this article belong to many nonlinear properties problem, for example material nonlinear, geometry nonlinear and so on. So complete this work by the mean of the FEM method which has the ability of calculating large deformation problems.Firstly, by means of CATIA software, design the geometry model base on structure parameters and dimension determined in last point. And in total there are twenty-two models have been constructed in this article.Secondly, by means of Hyper-mesh software, draw the elements grid of these models.Thirdly, import to Pam-crash, which belongs to ESI corp. is pre-progress software, to define different conditions for material and simulation parameters. Lastly, export and compute in Pam-safe and do post-progress work to get result.5. Confirmation and simulationThe beginning simulation is perfected and confirmed by the test of simplified B-pillar bend crashworthiness. And the test is finished in dynamic test-bed in Institute of Mechanical Science and Engineering of JiLin University. It is proved that the simulation is effective for the result of the test accorded with result of simulation.On the base of effctivity mentioned above, it is done some improvement to restriction ways of B-pillars for there is always one bad point in the test that the two extremes of B-pillars would raise after crash. It is very different with real B-pillar in side crash and replaces the structure of two spheres support in two extremes with one sphere support in one extreme and the other is displacement restriction.6. ConclusionIt is researched about six parameters, which constructing B-pillar structure, different bend crashworthiness level, and draw a lot of tables and pictures to compare these difference effect levels. Finally draw a conclusion and conclude some viewpoints in B-pillar design progress. |
