基于侧碰的车身梯度性能零部件防撞性能优化

发布时间：2018-03-02 23:36

本文选题：压溃试验　切入点：车身侧碰　出处：《大连理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：随着车身轻量化技术的不断发展,力学性能梯度变化的车身零部件开始得到广泛关注。针对车用钢材,拼焊技术、变厚度轧制技术、模具分区冷却技术等能够实现车身零部件呈梯度性能分布的特点。但怎样的梯度性能能够保证车身零部件具有更优的安全性能,目前还是国内外学者研究的重要内容。汽车主机厂通常从经验和加工的角度来进行梯度性能设计,而科研工作者则主要从优化仿真的角度去找到梯度性能零部件理论的最优情形。上述现象带来了一个主要问题即为理论与实际没有达到较好的结合,因此围绕该问题,结合实际应用背景,本文针对梯度性能零部件的防撞性能开展相应的研究。首先,基于压溃试验平台,开展相关动态大变形试验,验证建模方式与材料参数的可靠性。选取样件与仿真计算结果进行对比,发现两者变形模式、力一位移曲线的变化趋势基本一致。但也存在一定的问题,即在同样的准备条件下,试验的可重复度较低,每一次压溃试验后,样件的变形、破坏形式均不尽相同。其次,针对原始整车侧碰模型开展了简化工作,通过对比验证确定了简化模型的有效性。针对B柱在侧碰过程中的关键作用,确定了其性能的评价指标：最大侵入量Dmax、碰撞吸能EA。依据侵入量与重伤率的关系对B柱进行了合理的分区。对比分析64种不同梯度强度B柱的计算结果发现,B各部分强度变化则对其碰撞结果影响各不相同,其中中部强度对结果影响显著。对比分析27种不同梯度厚度B柱的计算结果发现,B柱中部厚度TMID的改变对计算结果影响显著。最后,基于所得数据拟合数值模型,结合优化算法分别得到两种梯度性能B柱的最优解集并与原始工况进行对比。通过径向基函数(RBF)对两种梯度性能B柱进行了模型拟合,采用非支配排序的带有精英策略的多目标优化算法(NSGAII)对所得数值模型进行优化设计。结果表明：梯度强度B柱的优化结果实际上相当于将3段式B柱简化成了2段式B柱,以上部强下部弱的形式分布,能够有效的提高防侵入性和吸能性,且与实际加工生产的经验吻合较好,具有实际应用价值。厚度梯度B柱的优化结果为中间厚,两端薄,优化结果与基准工况相比能显著提高防侵入性并兼顾吸能。综合两种梯度性能B柱与基准工况对比发现,优化后的梯度性能B柱综合性能均好于基准工况,且梯度厚度B柱的综合性能更为突出,具有更好的防侵入性能和轻量化效果。
[Abstract]:With the continuous development of the lightweight technology of automobile body, the body parts whose mechanical performance gradient changes have been paid more and more attention. For automotive steel, welding technology, variable thickness rolling technology, The die zone cooling technology can realize the gradient performance distribution of the body parts, but what kind of gradient performance can ensure the better safety performance of the body parts. At present, it is also an important research content of scholars at home and abroad. Automobile mainframe factories usually design gradient performance from the perspective of experience and processing. The researchers mainly find the optimal situation of the gradient performance parts theory from the angle of optimization simulation. The above phenomenon brings a major problem, that is, the theory is not well integrated with the practice, so it revolves around this problem. Combined with the practical application background, this paper carries out the corresponding research on the crashworthiness of the gradient performance parts. Firstly, based on the crashing test platform, the related dynamic large deformation test is carried out. The reliability of modeling method and material parameter is verified. Comparing the results of simulation with the sample, it is found that the deformation mode and the change trend of the force-displacement curve are basically the same. However, there are some problems. That is, under the same conditions, the repeatability of the test is low. After each crushing test, the deformation and failure forms of the samples are different. Secondly, the simplified work is carried out for the original side impact model of the whole vehicle. The effectiveness of the simplified model is determined by comparison and verification. In view of the key role of column B in the side impact process, The evaluation indexes of its performance are determined as follows: maximum invasion Dmax, collision energy absorption EA. according to the relation between invasion and serious injury rate, the B column is reasonably partitioned. The results of 64 different gradient strength B columns are compared and analyzed. Some changes in strength have different effects on the impact results. The central strength has a significant effect on the results. By comparing and analyzing the calculation results of 27 B columns with different gradient thickness, it is found that the change of TMID in the middle thickness of B column has a significant effect on the results. Finally, the numerical model is fitted based on the obtained data. In combination with the optimization algorithm, the optimal solution sets of two kinds of gradient B columns are obtained and compared with the original conditions. The two gradient B columns are fitted by the radial basis function (RBF). A multi-objective optimization algorithm with elite strategy (NSGA II) is used to optimize the numerical model. The results show that the optimization result of gradient strength B column is equivalent to that of simplifying 3-segment B-column into 2-segment B-column. The strong and weak distribution of the upper part can effectively improve the invasiveness and energy absorption, and it is in good agreement with the practical production experience, and has practical application value. The optimization result of the thickness gradient B column is middle thick and thin at both ends. Compared with the reference condition, the optimized results can significantly improve the anti-invasion and energy absorption. By comparing the two kinds of gradient performance B column with the reference condition, it is found that the optimized gradient performance B column is better than the reference condition. Moreover, the composite performance of gradient thickness B column is more outstanding, and it has better anti-invasion performance and light weight effect.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U463.82

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