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1、湖南大学 博士学位论文 汽车前碰撞吸能方法及其关键技术研究 姓名：白中浩 申请学位级别：博士 专业：车辆工程 指导教师：曹立波 20060918 博士学位论文 II 摘 要 汽车前碰撞在所有碰撞事故中占有最大的比例，碰撞事故发生后，往往导致严重的 后果。因此，汽车前碰撞安全性研究一直是汽车安全性研究领域中的重要研究主题。中 国作为发展中国家，对于经济型车的需求远大于欧、美、日等发达国家。尤其是微型客 车，约占全年各种汽车产销量的 20。为了满足正面碰撞法规要求，大多数微型客车由 原来的平头结构改成短头结构或在车前加装吸能结构，使其造型受到很大影响，长度空 间也受到限制。同时，增加的吸能结构对车
2、外行人造成更大的威胁。研究能够适合广大 微型客车使用的汽车前碰撞吸能方法及关键技术，尽量缩短吸能长度，在有限的车长内 尽量增加车内空间，不仅可以增加载客载货量及乘坐舒适性，而且可以使其造型得到更 大的自由度，对微型客车及经济型轿车具有重大的理论意义和现实意义。此外，利用主 被动结合技术研究开发一种新型的汽车前碰撞吸能装置， 使其能够在不可避免的碰撞事 故中降低乘员与车辆的损伤，并结合前保险杠安全气囊等部件，进一步改善车辆行人 碰撞事故中对行人的保护效果，也将具有重大的实用价值。 在此背景下，开展了本论文的研究工作，取得了以下几项主要研究成果： 1、创新性地提出了一种新型的基于反推设计原理的汽车
3、前碰撞逐级吸能方法。该 方法是根据汽车前部造型及碰撞安全性要求，反推汽车结构吸能长度，从而计算出理想 的碰撞加速度值范围；采用方形吸能梁结构并适当控制吸能梁的壁厚，在方形吸能梁内 部不同长度的合适位置上设置相应的加强板，逐级参与碰撞吸能，使碰撞加速度曲线达 到较理想的要求。采用该方法可以在尽量短的吸能长度内达到好的吸能效果，同时，便 于控制整车质量。同时，制造成本比较低，易于推广应用。 2、建立了 XXX 车型的有限元仿真模型，通过对增加诱导槽、内置方形梁、内置逐 级吸能加强板以及多种吸能结构的综合使用等多种设计方案的有限元数值仿真对比分 析，验证了本文提出的逐级吸能结构配合诱导槽的设计方案具
4、有更好的吸能效果。进而 以 XXX 车参数为例，并对内置逐渐吸能加强板结构和内置方形梁两种结构进行了整车 仿真分析对比，仿真结果表明逐级吸能方法具有更好的吸能能力。为了进一步提高微型 车前碰撞安全性，创新性地提出了一种非常实用的前碰撞传递式吸能结构，并对其进行 了仿真分析研究。 3、应用多刚体理论对逐级吸能结构在汽车前碰撞过程中对乘员损伤参数的影响进 行了深入分析。通过计算机仿真研究，提出了以纵梁内置逐级吸能加强板结构的目标碰 撞加速度曲线。同时，对 XXX 车型进行了乘员约束系统参数优化。 4、结合某公司 XXX 车的开发，在湖南大学汽车碰撞实验室开展了一系列的部件前 碰撞吸能台车试验和实车
5、碰撞试验。 结合仿真结果对台车碰撞试验和实车试验结果进行 博士学位论文 III 了深入分析。研究表明，逐级吸能结构能够在前碰撞发生时有效防护乘员，提高车辆的 安全性。 5、采用主被动结合技术提出了一种新型汽车前碰撞吸能装置，设计了其机电一体 化结构。通过 MADYMO 软件进行仿真，表明该装置在发生不可避免的碰撞事故中可以 有效的保护车辆，在车辆行人碰撞中，可以有效的对行人进行保护。结合主动安全技 术设计了该装置的触发算法并进行了实车验证， 根据该算法开发了该装置的测量与控制 系统硬件及软件，并对该装置进行了台车和实车试验研究。目前，该装置已经获得了国 家发明专利。 关键字：汽车前碰撞；吸能方
6、法；吸能装置；有限元仿真；乘员损伤；碰撞试验 博士学位论文 IV Abstract A passenger car frontal impact is one of the most frequent vehicle crash accidents. Serious consequences are often caused from this type of crash. It is therefore that a high priority was given to the protection of car occupants from frontal crashes in the v
7、ehicle safety field. There are larger demands of the economic cars in developing countries like China than that of the developed countries and areas, such as America, Japan and Europe. Especially, the minibuses accounted for twenty percent of various cars in Chinese passenger car market annually. To
8、 meet the requirement of car safety standard in a frontal crash, most of the minibuses have changed the front-end structures with an extended length to add an energy absorbing structure. This change has a considerable influence to the stylling, therefore a limited space in length can be used for the
9、 energy absorbing structure. At the same time the energy absorbing structure may have potential problem with pedestrian protection from crashes. It is significant and valuable to improve minibus front-end structures by developing of new method and key technologies for an energy absorbing structure.
10、For this purpose, the researches were carried out on shortening the energy absorption room to increase the space of the cars, which will not only increase the number of passengers or the quantity of cargo and comfort, but also get more degree of freedom on styling. In addition, a new type of energy
11、absorption device was developed in combination of active safety with passive safety counter-measures to mitigate the risks of passenger injuries and vehicle damages. A front bumper airbag was designed for pedestrian protection from car impacts This thesis has a contribution to development of a safer
12、 minibus and obtained following achievements: First, an innovatory method of energy absorption step by step was developed based on on the theory of reverse design. The length of energy absorption structure was derived by using reversing theory according to the demands of styling and crash law. In or
13、der to receive a collision acceleration pulse required in regulation test a front longitudinal beam was designed with a rectangular section and suitable thickness. Some reinforced brackets were added to the beam, which take part in the crash step by step at the different positions in the beam. This
14、method can lead to a good result in a minimal length of front beam. The quality of the minibus can be improved with low costs, and the method can be applied in development of other new minibus. Second, a finite element model of XXX vehicle was developed. The finite element was 博士学位论文 V used to simul
15、ate frontal impact with the detailed structures, such as adding grooves or rectangular beams or brackets or combination of those structures. Then, the case of XXX in frontal impact was taken for a comparing analysis based on results from the simulations of brackets and rectangular beams. The analysi
16、s indicated that the step by step energy absorption method with bracket is better than the method with rectangular beam. In order to improve the crash safety two new types of energy absorption structures for frontal crash are suggested innovatory, which are closed-loop energy absorption structure and closed-loop cavity energy absorption structure. A simulation study of these two structures is made. Third, the multi-rigid theory and MADYMO program was used to calculate the effect of the new
