被动柔性防护网中环形网片的力学性能及耗能研究

发布时间：2018-04-29 15:31

本文选题：被动柔性防护网结构 + 环形网片　；参考：《西南交通大学》2017年硕士论文

【摘要】：我国地势西高东低,地质构造多样,随着近些年的气候变化,地质灾害多发,其中崩塌落石因其发生突然、发生频率高、高冲击动能等,对山区交通干线、城镇等构成了严重的威胁。广大技术人员根据现场实际的崩塌落石发育特点以及地形地质条件积累了大量的实际应用经验,其中被动柔性防护网结构以其施工方便、干扰小、标准化生产、造价低、实用性强等众多特点在实际工程中被广泛应用。环形网片是被动柔性防护网结构的重要组成部分之一,而在实际工程应用中经常出现环形网片被击穿的破坏现象。本文以环形网片构件为研究对象,通过理论推导、数值模拟和试验数据对比分析等手段对环形网片进行了基础性的研究,本文主要完成了以下工作。(1)以材料与结构的能量吸收方面的相关理论为基础,理论推导了单个圆环在二力、四力和六力作用下的理论耗能公式,并与现有的文献结果进行了对比分析,证明了本文理论推导的正确性,为环形网片的耗能研究提供了一定的理论基础。(2)通过ANSYS/LS-DYNA软件建立与文献中同等尺寸、同等边界条件、同等冲击过程的环形网片,分别进行24kJ和45kJ作用下的落石冲击分析,将得到的数据与文献中的试验结果进行对比,证明了文中数值仿真建模的正确性,为数值分析环形网片的动力响应和耗能情况提供了一套合理的建模方法。(3)通过利用试验数据验证过的建模方法建立3.3m×6.6m的环形网片。首先,进行三种边界约束形式下的数值分析,对比落石冲击环形网片的动力响应和各种约束形式下的最大耗能;然后,分析是否考虑落石重力对环形网片耗能性能的影响,分为三种情况对其进行研究;最后,分析环形网片在落石不同冲击角度下的动力响应和耗能情况,根据冲击角度的不同,分为五种情况进行研究。(4)通过改变横、纵向的圆环数目建立不同尺寸的环形网片,分析落石垂直冲击中间位置时的受荷区域分布规律,定量的给出环形网片的理论耗能计算公式,为基于能量的整体防护结构体系设计提供一定的理论基础。
[Abstract]:With the climate change in recent years, geological disasters occur frequently in China, in which the collapse and falling stone occur suddenly, high frequency, high impact kinetic energy, etc., on the main traffic lines in mountainous areas. Towns and cities pose a serious threat. The vast number of technicians have accumulated a great deal of practical application experience according to the development characteristics of collapsing and falling rocks and the topographic and geological conditions. Among them, the passive flexible protective net structure has the advantages of convenient construction, small interference, standardized production and low cost. Many characteristics, such as strong practicability, are widely used in practical engineering. Annular mesh is one of the important parts of passive flexible protective net structure, and the breakdown of annular mesh is often occurred in practical engineering application. In this paper, the annular mesh component is taken as the research object, and the basic research is carried out by means of theoretical derivation, numerical simulation and comparative analysis of experimental data. Based on the theory of energy absorption of materials and structures, the theoretical energy dissipation formulas of a single ring under the action of two, four and six forces are derived. By comparing the results with the existing literatures, it is proved that the theoretical derivation of this paper is correct, which provides a theoretical basis for the study of energy dissipation in annular mesh. (2) the same size and boundary conditions as in the literature are established by using ANSYS/LS-DYNA software. Under the action of 24kJ and 45kJ, the annular mesh of the same impact process is analyzed respectively. The results obtained are compared with the experimental results in the literature, which proves the correctness of the numerical simulation modeling in this paper. A set of reasonable modeling method is provided for the numerical analysis of the dynamic response and energy dissipation of annular mesh. The annular mesh with 3.3m 脳 6.6m is established by using the modeling method verified by the experimental data. Firstly, the numerical analysis of three kinds of boundary constraint forms is carried out to compare the dynamic response and the maximum energy consumption under various constraint forms of the annular mesh, and then, whether to consider the influence of the falling gravity on the energy dissipation performance of the annular mesh is analyzed. Finally, the dynamic response and energy dissipation of annular mesh at different impact angles are analyzed. According to the impact angle, it is divided into five situations. The number of rings in longitudinal direction is used to establish annular mesh with different sizes, and the distribution law of the loading area at the middle position of vertical impact is analyzed, and the theoretical energy consumption formula of the annular mesh is given quantitatively. It provides a theoretical basis for the design of the whole protection structure based on energy.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U417.1

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