本文選題：壓潰試驗　切入點：車身側碰　出處：《大連理工大學》2016年碩士論文　論文類型：學位論文

【摘要】：隨著車身輕量化技術的不斷發(fā)展,力學性能梯度變化的車身零部件開始得到廣泛關注。針對車用鋼材,拼焊技術、變厚度軋制技術、模具分區(qū)冷卻技術等能夠?qū)崿F(xiàn)車身零部件呈梯度性能分布的特點。但怎樣的梯度性能能夠保證車身零部件具有更優(yōu)的安全性能,目前還是國內(nèi)外學者研究的重要內(nèi)容。汽車主機廠通常從經(jīng)驗和加工的角度來進行梯度性能設計,而科研工作者則主要從優(yōu)化仿真的角度去找到梯度性能零部件理論的最優(yōu)情形。上述現(xiàn)象帶來了一個主要問題即為理論與實際沒有達到較好的結合,因此圍繞該問題,結合實際應用背景,本文針對梯度性能零部件的防撞性能開展相應的研究。首先,基于壓潰試驗平臺,開展相關動態(tài)大變形試驗,驗證建模方式與材料參數(shù)的可靠性。選取樣件與仿真計算結果進行對比,發(fā)現(xiàn)兩者變形模式、力一位移曲線的變化趨勢基本一致。但也存在一定的問題,即在同樣的準備條件下,試驗的可重復度較低,每一次壓潰試驗后,樣件的變形、破壞形式均不盡相同。其次,針對原始整車側碰模型開展了簡化工作,通過對比驗證確定了簡化模型的有效性。針對B柱在側碰過程中的關鍵作用,確定了其性能的評價指標：最大侵入量Dmax、碰撞吸能EA。依據(jù)侵入量與重傷率的關系對B柱進行了合理的分區(qū)。對比分析64種不同梯度強度B柱的計算結果發(fā)現(xiàn),B各部分強度變化則對其碰撞結果影響各不相同,其中中部強度對結果影響顯著。對比分析27種不同梯度厚度B柱的計算結果發(fā)現(xiàn),B柱中部厚度TMID的改變對計算結果影響顯著。最后,基于所得數(shù)據(jù)擬合數(shù)值模型,結合優(yōu)化算法分別得到兩種梯度性能B柱的最優(yōu)解集并與原始工況進行對比。通過徑向基函數(shù)(RBF)對兩種梯度性能B柱進行了模型擬合,采用非支配排序的帶有精英策略的多目標優(yōu)化算法(NSGAII)對所得數(shù)值模型進行優(yōu)化設計。結果表明：梯度強度B柱的優(yōu)化結果實際上相當于將3段式B柱簡化成了2段式B柱,以上部強下部弱的形式分布,能夠有效的提高防侵入性和吸能性,且與實際加工生產(chǎn)的經(jīng)驗吻合較好,具有實際應用價值。厚度梯度B柱的優(yōu)化結果為中間厚,兩端薄,優(yōu)化結果與基準工況相比能顯著提高防侵入性并兼顧吸能。綜合兩種梯度性能B柱與基準工況對比發(fā)現(xiàn),優(yōu)化后的梯度性能B柱綜合性能均好于基準工況,且梯度厚度B柱的綜合性能更為突出,具有更好的防侵入性能和輕量化效果。
[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.
【學位授予單位】：大連理工大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：U463.82

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