泡沫铝夹层板的局部压缩性能与能量吸收性能研究

发布时间：2018-12-07 12:15

【摘要】：由于泡沫铝芯中含有大量的胞孔,泡沫铝夹层板在承受较大的撞击破坏时,可以产生较大的塑性变形,从而在变形过程中可以吸收大量的能量。然而,在实际应用中,泡沫铝夹层板与其它板材连接使用时有许多缺陷,连接处受力不均,连接不稳固,都会给局部甚至整体结构性能带来严重的影响,因此,泡沫铝夹层板与致密板材的连接问题以及对其连接部位强度的合理加强也是今后研究的一个重要话题。在与其他板材进行连接之前,首先得对泡沫铝夹层板进行前期的薄化处理,将泡沫铝夹层板连接的一端进行局部压实,以便满足连接要求。基于上述原因,对泡沫铝夹层板的局部压缩性能开展了研究,具体研究的内容和成果如下:首先,对发泡过程进行理想假设的基础上,建立了三种二维随机模型和一种三维随机球模型,通过调节模型生成界面,控制模型的长度、宽度和孔隙率等参数,可以很方便的生成所需模型。其次,选用泡沫铝夹层板二维随机圆模型,通过有限元分析软件ANSYS/LS-DYNA,对泡沫铝夹层板在不同加载速率下的压缩行为进行了仿真研究。在准静态压缩的过程中,泡沫铝夹层板的塑性变形首先发生在孔壁薄弱处,而在高加载速率下,泡沫铝夹层板首先在压缩面附近发生变形,产生局部密实。在动态加载速率下,泡沫铝夹层板底部面板的应力应变曲线出现一定的延迟,且随着加载速率的增加,延迟的时间也会随着增加。另外,基于泡沫铝夹层板的二维随机圆模型,通过使用正交模拟实验、极差分析和方差分析,研究了孔隙度、孔径、加载速率和泡沫铝芯厚度对泡沫铝夹层板的能量吸收性能的影响。研究结果表明此四种变量对泡沫铝夹层板的能量吸收性能的影响程度依次如下:孔隙度P胞孔半径R加载速率V泡沫铝芯厚度H。此外,随着孔隙度、孔径的增加,泡沫铝夹层板吸收的能量逐渐地减小,而随着加载速率的增加,泡沫铝夹层板吸收的能量逐渐地增加,泡沫铝芯的厚度对泡沫铝夹层板的能量吸收性能影响很小。最后,在电子万能试验机上,分别对不同孔径、孔隙度的泡沫铝夹层板进行了准静态局部压缩性能研究。泡沫铝夹层板的承载能力与孔径大小和孔隙度大小呈反比例关系,随着孔径和孔隙度地增加,其承载能力逐渐地减小。由于泡沫铝夹层板基质材料是铝硅基体,应力应变曲线有明显地抖动。通过仿真和实验对比,发现两者应力应变曲线的变化趋势基本一致,数值相差较小,通过理论分析阐述了曲线变化的机理,进一步验证了实验结果的正确性以及数值模拟的可行性。
[Abstract]:Because there are a large number of cellular holes in the aluminum foam core, the foam aluminum sandwich plate can produce large plastic deformation when it is subjected to large impact damage, thus absorbing a large amount of energy in the process of deformation. However, in practical application, there are many defects in the connection of foam aluminum sandwich plate with other plates. The joint is not uniform in force, and the connection is unstable, which will bring serious influence to the local and even the whole structure performance. It is also an important topic to study the connection between foam aluminum sandwich plate and compact plate and the reasonable strengthening of the strength of the joint part in the future. Before connecting with other plates, the foam aluminum sandwich plate should be thinned in the early stage, and the one end of the foam aluminum sandwich plate should be partially compacted in order to meet the connection requirements. Based on the above reasons, the local compression performance of aluminum foam sandwich plate is studied. The specific research contents and results are as follows: first, on the basis of the ideal assumption of foaming process, Three two-dimensional stochastic models and a three-dimensional random sphere model are established. By adjusting the interface of the model and controlling the parameters of the model, such as length, width and porosity, the required model can be generated conveniently. Secondly, the compression behavior of aluminum foam sandwich plate under different loading rates is simulated by finite element analysis software ANSYS/LS-DYNA, which is based on the two-dimensional random circle model of aluminum foam sandwich plate. In the process of quasi-static compression, the plastic deformation of the aluminum foam sandwich plate first occurs in the weak part of the hole wall, while at high loading rate, the plastic deformation of the foam aluminum sandwich plate first occurs near the compression surface, resulting in local compaction. At the dynamic loading rate, the stress-strain curve of the bottom panel of the aluminum foam sandwich plate has a certain delay, and with the increase of the loading rate, the delay time will also increase. In addition, based on the two-dimensional random circle model of aluminum foam sandwich plate, the porosity and pore size are studied by means of orthogonal simulation experiment, range analysis and variance analysis. The effect of loading rate and thickness of aluminum foam core on the energy absorption of aluminum foam sandwich plate. The results show that the influence of these four variables on the energy absorption performance of aluminum foam sandwich plate is as follows: porosity P cell radius R loading rate V foam aluminum core thickness H. In addition, with the increase of porosity and pore size, the energy absorbed by the foam aluminum sandwich plate decreases gradually, while with the increase of loading rate, the energy absorbed by the foam aluminum sandwich plate increases gradually. The thickness of aluminum foam core has little effect on the energy absorption of aluminum foam sandwich plate. Finally, the quasi-static local compression properties of aluminum foam sandwich plates with different pore sizes and porosity were studied on an electronic universal testing machine. The bearing capacity of aluminum foam sandwich plate is inversely proportional to the pore size and porosity, and decreases gradually with the increase of pore size and porosity. Because the matrix material of aluminum foam sandwich plate is aluminum-silicon matrix, the stress-strain curve jitter obviously. Through the comparison of simulation and experiment, it is found that the variation trend of stress-strain curve is basically the same, and the difference of numerical value is small. The mechanism of curve variation is explained through theoretical analysis. The correctness of the experimental results and the feasibility of numerical simulation are further verified.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.21;TB383.4

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