【作者】 任志远；

【导师】 刘志芳；

【作者基本信息】 太原理工大学 ， 流体力学， 2012， 硕士

【摘要】 泡沫铝填充薄壁金属管的复合结构广泛地应用于在减轻结构质量的前提下提高结构的抗冲击性能和能量吸收能力。本文以泡沫铝为芯层的单层薄壁金属圆管和双层薄壁金属圆管为研究对象,利用有限元软件ANSYS/LS-DYNA模块进行了数值仿真分析,研究了轴向载荷作用下两种填充结构的变形过程和吸能特性。根据已有的实验资料,建立有限元模型,模拟结果与实验结果吻合,充分验证了模型的正确性。在此基础上,考虑了金属圆管的几何尺寸和芯层材料的密度对填充结构吸能性能的影响,根据各个填充结构的径向位移分布曲线、应力云图和能量吸收曲线,对比分析各种因素对复合填充结构的变形和能量吸收能力的影响。在同等冲击条件下和相同时间内,对相同儿何参数的单层薄壁金属圆管填充结构和双层薄壁金属圆管泡沫铝填充结构进行对比,对比分析两种结构的能量吸收曲线,评价两者在吸能性能方面的优劣性。本文得到的主要结果如下：1、在轴向冲击载荷作用下,泡沫铝复合填充结构的能量吸收量远大于单独的泡沫铝或薄壁金属空管结构的能量吸收量。2、在相同的冲击能量下,填充结构的长度越长,填充泡沫金属的密度越小,薄壁金属管的厚度越薄,两种填充结构被压缩的轴向位移越大。填充结构的长度和填充泡沫金属的密度对两种填充结构的平均应力影响不大,而两种填充结构的平均应力会随着薄壁金属管厚度的增大而增大。填充结构的长度对两种填充结构的吸能性能影响不大,而泡沫金属的密度越大,薄壁金属管的厚度越大,两种填充结构的吸能性能会越强。3、在相同冲击质量和冲击速度下,由于内外薄壁金属圆管与泡沫铝芯层间的相互作用,单层薄壁金属圆管泡沫铝填充结构的最大径向位移要比双层薄壁金属圆管泡沫铝填充结构大,而平均应力要比双层薄壁金属圆管泡沫铝填充结构的小。由于双圆管填充结构中泡沫金属被充分压缩,在相同时间内双层薄壁金属圆管泡沫铝结构比单层薄壁金属圆管泡沫铝结构吸收的能量更多,说明填充结构中泡沫金属的压缩程度对该结构的能量吸收影响较大。更多还原

【Abstract】 Thin-walled metallic circular tubes with aluminum foam filler was widely used in improving structure crashworthiness, energy absorption and reducing structure weight. By using the finite element software ANSYS/LS-DYNA, the single thin-wall metallic circular tube and double thin-wall metallic circular tube with foam aluminum filler under axial impact loading are researched, and the deformation process and energy absorption of two kinds of composite structures are analysised. On the basis of the previous experimental data, the finite element model has been established. The numerical results are good agreement with the experimental results. So the finite element models in this paper are right. According to the radial displacement distribution curve, the von misses stress and the energy absorption curves of each composite structure, the model geometry dimension and the densities of aluminum foam impact upon the energy absorption of the composite structure. Under the same impact conditions, the absorbing energy curves of the single circular tube composite structure and double circular tube composite structure are compared at the same time, and the advantages and disadvantages of two kinds of composite structures are given. The main conclusions in this paper are as follows:1. Under axial impact loading, the amount of absorbing energy of thin-walled metallic circular with aluminum foam filler is greatly bigger than that of aluminum foam or metallic tubes alone.2. The longer the length of the model, the smaller the densities of aluminum foam filler and the thinner the thickness of metallic tube, the bigger the axial displacement of two kinds of structures when they are compressed. The thicker the thin-walled metallic tube, the bigger the von misses stress. But the different length of the composite structure and densities of the aluminum foam have little effect on the mean stress of two kinds of structures. Increasing the thickness of the thin-wall metallic tube or the density of aluminum foam, the ability of absorption energy of the composite structures is improved, but the length of composite structure has little effect on that.3. Under the same impact quality and impact velocity, because of the interaction between double tubes and foam aluminum, the maximum radial displacement of single circular tube composite structure is bigger than that of double circular tube composite structure, but the von misses stress is smaller. Because of aluminum foam between internal and external tube is fully compressed, the amount of absorbing energy of double circular tube composite structure is bigger than single circular tube composite structure in the same time. Numerical result shows that aluminum foam compressed degree in composite structure has big impact on absorbing energy of the composite structure.更多还原