Optimization On The Crashworthiness Of Mini-van's B-pillar For Side Impact

Vehicle collisions are becoming one of the most important topics in the research of modern automobile technology.Among all the types of collisions,the incidence of side impact is pretty high,and the occupant mortality rate is also very high.B-pillar is the first component to be involved in side impact.Its strength and stiffness directly determine the crashworthiness of the vehicle in side impact.In order to optimize crashworthiness of minivan's B-pillar in side impact,this thesis mainly carries out the following research works:(1)Based on HyperMesh and LS-DYNA finite element softwares,the vehicle's side impact model is established.The collision of the side structural parts is analyzed from three aspects,including the vehicle body deformation,force transmission path optimization and energy distribution.It is confirmed that the focus of this study is on the B-pillar.(2)Each component test condition is designed,such as loading distance 150 mm,loading speed 5mm/min(simulation loading speed 2mm/ms),support cylinder and loading cylinder diameter 30 mm,span distance 820 mm,and supporting of both ends are simply supported and the loading position is in the middle of the beam sample.According to the certain moment of inertia of the section,the section of the first bending position of the B-pillar is equivalently reduced to a regular rectangular section,and its length×width sizes are 130mm×85mm.(3)A quasi-static three-point bending test device is designed,it is also confirmed that the evaluation indexes used in this test are average force and peak force.For the three research factors of material,thickness,and aspect ratio,the influence of bending performance is investigated.For the material factor,the higher the yield strength of the material used,the better the bending performance of the thin-walled beam;for the thickness factor,the greater the thickness,the better the bending performance of the thin-walled beam,but it can not always increase.In addition,the thin-walled beam's inner plate plays a minor role in bending resistance,the bending performance of thin-walled beam is mainly reflected by the outer plate;for the aspect ratio of the cross-section,when the perimeter of the section is constant,the aspect ratio is larger,that is,the more flattened shape of the thin-walled beam is,the worse the bending performance will be.(4)The B-pillar structure is guided by the application of the obtained bending performance law,and the B-pillar with optimized cross-section is obtained.Then the orthogonal test design technique is used in the vehicle side impact finite element model.Based on the Kriging approximation model and combined with the NSGA-II optimization algorithm,the minimum mass m of the B-pillar and the minimum amount of abdominal intrusion D are two objective functions.Optimize the five parameters of the outer plate's material and thickness of the B-pillar,the material and thickness of the reinforced plate,and the inner plate's material,and obtain an optimized B-pillar combination scheme with optimal multi-target performance.Through the finite element simulation,the optimization simulation results are compared with the initial simulation results,the mass of the B-pillar under the optimized plan is reduced by 10.77%,and the abdominal intrusion is also reduced by 28.51%,so as to effectively verify the accuracy of the optimization scheme.The results show that the optimization method is reliable.