轴向冲击载荷下梯度薄壁圆管的动力响应

发布时间：2018-03-20 22:21

本文选题：薄壁圆管　切入点：屈曲　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：薄壁圆管作为一种比较常见的能量吸收构件,具有自身结构稳定,在轴向载荷下发生褶皱屈曲变形,屈曲压实过程能量吸收可控的优点,因此被广泛的应用于车辆安全、施工工程等与碰撞安全密切相关的领域。对轴向载荷下薄壁圆管的屈曲变形行为的研究从上个世纪60年代开始陆续出现,但这些文献大多针对均匀壁厚的薄壁圆管的褶皱变形形态开展实验及理论分析研究,而对梯度圆管在动态载荷下的动力响应行为却鲜有报道。近年来关于泡沫材料轴向冲击过程中的冲击波模型研究的大量涌现,为轴向冲击载荷下薄壁圆管动力响应的研究模型的建立提供了新的思路。本文通过对动态载荷下均匀壁厚圆管屈曲变形的研究分析,将冲击波模型应用于圆管在轴向冲击下的变形过程,分析了薄壁圆管轴向冲击下的动力响应特征及吸能缓冲特性。将理论模型与有限元模拟结果对比发现直接使用薄壁圆管初始壁厚并不能很好地预测结构变形过程中配重块的速度变化规律,将模型中使用的圆管壁厚修正为其在屈曲变形过程中实际压实的壁厚,得到修正后的理论模型计算结果与有限元模拟结果吻合较好,证明了修正后的理论模型能够较好地预测轴向动态载荷下薄壁圆管的动力响应。在均匀壁厚圆管的冲击波模型的基础上,本文提出了外径不变,壁厚随圆管轴向变化的梯度圆管。当梯度圆管薄壁侧为冲击端时,冲击过程中的屈曲褶皱会从冲击端产生;而当梯度圆管厚壁侧为冲击端时,圆管两侧都会产生屈曲变形,本文对这两种工况下分别进行理论推导和有限元模拟,并分析了无量纲参数(质量比、厚径比、梯度参数)对结构吸能特性的影响。可以得到的结论包括:使用冲击波模型可以较好地预测轴向冲击载荷下均匀和梯度薄壁圆管的缓冲吸能过程;梯度圆管的缓冲吸能特性优于均匀圆管,且圆管壁厚差越大,缓冲吸能性能越好。
[Abstract]:As a relatively common energy absorption component, thin walled circular pipe has the advantages of stable structure, fold buckling and deformation under axial load, controllable energy absorption during buckling and compaction, so it is widely used in vehicle safety. The research on buckling and deformation behavior of thin-walled circular pipe under axial load has appeared since -40s. However, most of these documents have carried out experimental and theoretical analysis on the shape of fold and deformation of thin-walled circular tubes with uniform wall thickness. However, there are few reports on the dynamic response behavior of gradient circular tubes under dynamic loading. In recent years, a large number of researches on shock wave models during axial impact of foam materials have emerged. This paper provides a new idea for the establishment of dynamic response model of thin-walled circular pipe under axial impact load. In this paper, the buckling deformation of uniform thick circular tube under dynamic load is studied and analyzed. The shock wave model is applied to the deformation process of a circular tube under axial impact. The characteristics of dynamic response and energy absorption and cushioning of thin-walled circular tubes under axial impact are analyzed. Comparing the theoretical model with the results of finite element simulation, it is found that the direct use of initial wall thickness of thin-walled circular pipes can not predict the deformation process of structures well. The law of velocity variation of medium weight distribution block, The wall thickness of the circular pipe used in the model is modified to the actual compacted wall thickness in the process of buckling and deformation. The calculated results of the modified theoretical model are in good agreement with the results of the finite element simulation. It is proved that the modified theoretical model can predict the dynamic response of thin-walled circular tubes under axial dynamic loading. On the basis of the shock wave model of uniform wall thick circular tubes, it is proposed that the external diameter is invariant. When the thin-walled side of the gradient tube is the impact end, the buckling fold will occur from the impact end, and when the thick wall side of the gradient tube is the impact end, the buckling deformation will occur on both sides of the pipe. In this paper, theoretical derivation and finite element simulation are carried out under these two conditions, and dimensionless parameters (mass ratio, thick-diameter ratio, thickness to diameter ratio) are analyzed. The results are as follows: shock wave model can be used to predict the energy absorption process of uniform and gradient thin-walled tubes under axial shock loading; The buffer energy absorption of gradient circular tube is better than that of uniform circular tube, and the bigger the wall thickness difference is, the better the buffer energy absorption performance is.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O347.3

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