自冲铆接头动力学数值模拟与疲劳分析

发布时间：2018-12-19 10:52

【摘要】：自冲铆接是一种很有潜力的连接工艺,尤其对于轻型材料(轻合金、复合材料等)的连接。自冲铆接采用冲头将一个半空心的铆钉压入板材,铆钉管腿端部在嵌入板材的过程中喇叭状张开变形,在两层板或多层板中形成机械内锁,从而将上板和下板牢固地连接在一起。尽管自冲铆技术是一种新型的薄板连接技术,但它的机械性能比传统的点焊好。自冲铆技术被誉为下一代连接技术,是汽车轻量化过程中的一项关键技术,已在汽车行业得到广泛的应用。本论文利用数值模拟方法及实验方法研究了自冲铆接成型过程。用有限元软件LS-DYNA基于Cowper-Symonds材料模型建立了2D模型,用Lagrange方法及r-自适应网格划分技术模拟了整个铆接成型过程。结合铆接实体实验的载荷-位移曲线及接头剖面图验证了数值模拟的合理性。分析了凹模凸台尺寸、铆钉尺寸、动静摩擦系数、塑性应变比等参数对成型的影响,从而可以更好的对铆接过程的参数进行优化设计。利用有限元软件ANSYS对自冲铆接头进行静力学分析、动力学分析及疲劳分析。通过静力学分析得出最大应力主要分布在上下两板相互接触靠近铆钉孔的位置及上板与铆钉头部相接触的位置。对模态振型的研究提取了前25阶振型,分析得到横向振动的偶数振型关于两板搭接位置对称,搭接位置处在振型的峰值处。说明两板搭接位置对白冲铆接的机械性能有较大的影响,是疲劳分析的关键位置。对自冲铆接试件进行了拉伸剪切实验。通过对4组数据的研究对比发现,2系列铝合金自冲铆接-粘接试件的静态拉伸强度大于2系列铝合金自冲铆接试件。2系列铝合金自冲铆接试件的静态拉伸强度大于2系列铝合金压印连接试件。5系列铝合金自冲铆接试件的静态拉伸强度超过了5000N。为下阶段自冲铆接头的疲劳分析提供了应力信息。利用ANYSY/FE-SAFE有限元软件对5052铝合金自冲铆接头进行了疲劳分析。研究显示：疲劳破坏常常在上下两板相互接触靠近铆钉孔的位置,以及上板与铆钉头部接触并靠近铆钉孔的位置。通过ANSYS/LS-DYNA软件模拟了铆接接头裂纹扩展的整个过程。本文主要目的是实现自冲铆接头动力学数值模拟及疲劳分析,为更深一步的研究提供基础。
[Abstract]:Self-impact riveting is a potential bonding process, especially for lightweight materials (light alloys, composites, etc.). The self-punching riveting uses the punch head to press the semi-hollow rivet into the plate, and the end of the rivet tube leg opens and deforms in the process of embedding the plate, forming a mechanical internal lock in the two or multilayer plates. Thus, the upper and lower plates are firmly connected together. Although self-punching riveting technology is a new type of thin plate bonding technology, its mechanical properties are better than that of traditional spot welding. Self-punching riveting technology, known as the next-generation connection technology, is a key technology in the process of automotive lightweight, and has been widely used in the automotive industry. In this paper, the process of self-punching riveting is studied by numerical simulation and experiment. 2D model based on Cowper-Symonds material model is established by finite element software LS-DYNA. The whole riveting process is simulated by Lagrange method and r-adaptive mesh generation technique. The rationality of the numerical simulation is verified by combining the load-displacement curve of riveted solid experiment with the joint profile. The influence of die punch size, rivet size, static and static friction coefficient and plastic strain ratio on the forming process is analyzed, so the parameters of riveting process can be optimized. The static analysis, dynamic analysis and fatigue analysis of self-impact riveting head are carried out by using finite element software ANSYS. Through statics analysis, the maximum stress is mainly distributed in the position where the upper and lower plates are in contact with each other near the rivet hole and where the upper plate is in contact with the head of the rivet. The first 25 modes are extracted from the study of modal modes. The analysis shows that the even vibration modes of transverse vibration are symmetrical for the lap position of the two plates, and the lap position is at the peak value of the vibration mode. The results show that the lap position of two plates has great influence on the mechanical properties of white impact riveting and is the key position of fatigue analysis. Tensile shear experiments were carried out on self-impact riveted specimens. Through the study of four groups of data, we found that, The static tensile strength of 2 series aluminum alloy self-impact riveting specimens is greater than that of 2 series aluminium alloy self-impact riveting specimens. The static tensile strength of 2 series aluminium alloy self-impact riveting specimens is greater than 2 series aluminium alloy imprint joint specimens The static tensile strength of 5 series aluminum alloy self-punching riveted specimens exceeds 5 000 N. It provides the stress information for the fatigue analysis of the self-impact riveting head in the next stage. Fatigue analysis of 5052 aluminum alloy self-impact riveting head was carried out by using ANYSY/FE-SAFE finite element software. The results show that the fatigue failure is usually in the position where the upper and lower plates contact each other near the rivet hole and the upper plate and the head of the rivet and close to the rivet hole. The whole process of riveted joint crack growth is simulated by ANSYS/LS-DYNA software. The main purpose of this paper is to realize the dynamic numerical simulation and fatigue analysis of the self-punching riveting head, and to provide the foundation for further research.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH131.1

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