【作者】 赵媛媛；

【导师】 喻健良；

【作者基本信息】 大连理工大学 ， 化工过程机械， 2012， 硕士

【摘要】 管道被应用于生产和生活的各个方面,在其使用过程中,不可避免的会遭受损伤和破坏。对管道受冲击后的变形和失效的研究对管道的设计有着重要意义,可以为有效地提高管道抗冲击性能提供指导性意见。本文利用ANSYS/LS-DYNA软件建立了受弹体冲击的直管和弯管的有限元模型,建模过程结合自编APDL语言,分析了管道的变形和失效特征。主要的工作和结论如下：(1)对前人的研究成果进行了总结,客观的介绍了下研究所存在的不足,确定论文的研究重点,研究的内容以及技术路线。(2)对ANSYS/LS-DYNA软件、冲击过程有限元基本理论：非线性理论,塑性材料基本理论给出了介绍。建立了弹体冲击管道的有限元模型,并对其做出了验证。探讨了模型单元和材料的选择,并分析了摩擦系数和沙漏对模拟结果的影响。(3)建立了自由圆管和悬臂管受平头弹体冲击的有限元模型。对模型的网格进行了独立性分析,选择单元边长为1进行网格划分。研究了子弹速度V、圆管和弹体直径比Do/dm、圆管径厚比Do/δ对圆管整体弯曲变形的影响。发现V和Do/d对圆管变形挠度ω的影响较大,Do/dm。对其影响较小。两种约束条件下,挠度ω均随V和Do/δ的增大而增大。(4)建立了90°弯管受半球头弹体冲击的有限元模型。网格独立性分析后选择单元边长为1,沙漏系数选择为0.12,模型精确度和沙漏能符合要求。考虑了弯管外径D。和壁厚δ,以及不同弹体直径dm弹体质量m在不同的内压P和冲击角度(即曲率半径r)下对临界破裂动能E.的影响。研究发现,随着δ、dm和m的增加,临界破裂动能Er均随之增加。Do对Er的影响不大。P和r对Er的影响非常明显。(5)建立了加筋管受半球头弹体冲击的有限元模型。对模型进行网格独立性和沙漏能分析,选择单元边长为0.9,沙漏能系数为0.05。对筋的宽度β,厚度h和位置a、管的曲率半径r以及模型的切线模量Etan对加筋管抗冲击性能的影响进行了分析。研究发现,随着a的改变,Er存在先增大后减小的趋势；筋的厚度对E.的影响不大,可以忽略；Er随β先增加,后减小；随着r的增加,Er先增加,后减小,最后趋于平稳。加筋管的破裂模式主要为撕裂型破坏和拉伸型破坏；子弹的动能大部分被加筋管消耗吸收,转化为加筋管的变形能；当子弹速度V<200m/s时,弯管吸收的能量随之增加,当V>200m/s时,弯管吸收能量先减小,最后趋于平稳。更多还原

【Abstract】 Pipes are widely used in the field of production and life. In its use of the process, damage and failure are inevitable. Research on the deformation and failure is of great significance. The software of ANSYS/LS-DYNA and ANSYS parametric design language were used in this paper to build the model of pipes impacted by missiles. Moreover, the deformation and failure of the pipeline were researched. The main work and the conclusions are as follows:(1)Existing research productions were summarized and the shortage of the study was objectively described. The concerned research actuality confirmed the aspects and the emphases of this paper. The research technique route was given meanwhile.(2)The software of ANSYS/LS-DYNA and the basic theory of finite element about impact, including nonlinear theory and the basic theory of plastic materials, were systematically described. The model of the pipe impacted by the missile was builded and its accuracy was verified. The details of the element and material adopted in the model were given. The friction factor and hourglass were also taken into consideration. Two main influence factors of hourglass, grid density and hourglass coefficient, were analysed.(3)Builded the model of the free pipe and the cantilever pipe and maked the grid dependence analysis, then chose1as the element side. Maked a study of the influence of the missile speed, Do/dm and Do/δ on the large deformation of circular pipe. It was found that V and Do/δ had a larger influence on the deformation while Do/dm had little. Under the two kinds of constraint, ω increased with V and Do/δ.(4)Builded the model of elbow bend impacted by the hemisphere missile. Chose1as the element size according to the grid dependence analysis. When hourglass coefficient was0.12, the hourglass energy would meet the demand. The external diameter Do and wall thickness δ of elbow, the diameter dm and quality m of the missile were taken into consideration to study their influence on the critical fracture kinetic energy. The study found that Er increased with the δ、dm and m. Do had little affect on Er. By contrast, the pressture and radius of curvature had obvious influence on it.(5) Builded the model of stiffened elbow bend impacted by the hemisphere missile. Analyzed the grid independence and the rationality of the hourglass energy. Choose0.9as the element size and0.05to be the hourglass coefficient. Studied the influencing factor on the impact resistance, just as the width β, thickness h and position a of the stiffener, the radius of curvature of the elbow bend and the material parameters of the model. The study showed that Er increased first and then decreased with the change of the stiffener’s position and width. The thickness of the stiffener had little influence on Er. Along with the increase of r, Er first increased and then decreased, finally stabilized. The mainly failure mode of the elbow bend included tearing failure and stretching failure. Most of the missile’s kinetic energy changed into the internal energy of the elbow bend. When V≤200m/s, the energy absorption of the elbow bend would increase along with V. When V>200m/s, it would decrease and then barely grew.更多还原