接触联接结构的故障预测和动力学特性分析

发布时间：2018-01-27 13:48

本文关键词： 接触有限元疲劳裂纹萌生寿命疲劳裂纹扩展寿命剩余寿命动力学特性　出处：《南京航空航天大学》2012年硕士论文　论文类型：学位论文

【摘要】：接触联接结构广泛用于各类机械结构中，例如螺栓联接结构、铆钉联接结构、销钉联接结构等。由于联接部位有接触的存在，并且这些联接结构通常处于恶劣的工作环境，经常会出现疲劳失效问题；近年来由于复杂结构的大型化和柔性化，使联接部动力学特性对整机性能的影响显得更加重要。本文通过有限元仿真对吊耳螺栓联接结构的失效故障预报和飞机蒙皮与长桁铆接结构的动力学特性进行了研究，探讨了在复合载荷作用下并考虑零件表面之间的接触现象时，结构件的疲劳裂纹产生以及扩展过程和速度，从而提高了结构的失效故障预报的可靠性，比较了传统不考虑接触现象时的结果，发现接触现象对裂纹扩展速度以及模态参数都有不可忽视的影响，并采用灰色模型对考虑接触时结构的剩余寿命进行了预测。建立了吊耳螺栓联接结构有限元模型，通过应力分析预报出故障危险点，并分析了预紧力和剪力对危险点应力的影响，最后计算了考虑接触和不考虑接触的疲劳裂纹萌生寿命，发现接触对疲劳裂纹萌生寿命有一定影响。建立了含裂纹的吊耳螺栓联接结构有限元模型，分析了接触、裂纹深度以及椭圆裂纹长短半轴之比对应力强度因子的影响，，分析了接触对裂纹扩展速率的影响，并计算了考虑接触和不考虑接触的疲劳裂纹扩展寿命，发现接触对裂纹扩展速率和疲劳裂纹扩展寿命有一定影响。提出了吊耳螺栓联接结构的剩余寿命预测流程，利用新陈代谢灰色预测模型预测了应力强度因子随裂纹深度变化值，进一步计算了裂纹扩展速率随裂纹深度变化值，最后计算了吊耳螺栓联接结构的疲劳剩余寿命。建立了飞机蒙皮与长桁铆接联接有限元模型，对系统进行模态分析，然后在不同工况下对系统进行瞬态动力学分析，研究了接触和预紧力对系统固有频率等动态特性的影响，发现实际的接触情况对整个系统的动力学特性影响显著。
[Abstract]:Contact connection structure is widely used in various mechanical structures, such as bolt connection structure, rivet connection structure, pin connection structure, etc. And these connection structures are usually in a bad working environment, often appear fatigue failure problem; In recent years, due to the large-scale and flexible of complex structures. In this paper, the finite element simulation is used to predict the failure of hoisting bolt connection structure and the dynamic characteristics of aircraft skin and long truss riveting structure. Research. In this paper, the fatigue crack generation, propagation process and speed of structural parts under the action of composite load and considering the contact phenomenon between parts surfaces are discussed, thus improving the reliability of structural failure prediction. It is found that the contact phenomenon has an important effect on the crack growth speed and modal parameters. The residual life of the structure considering contact is predicted by grey model. The finite element model of bolt connection structure is established, and the fault danger point is predicted by stress analysis, and the influence of preload force and shear force on the stress of dangerous point is analyzed. Finally, the fatigue crack initiation life with and without contact is calculated, and it is found that contact has some influence on the fatigue crack initiation life. The finite element model of the bolt connection structure with cracks is established, and the effects of contact, crack depth and the ratio of elliptical crack length and half axis on the stress intensity factor are analyzed. The influence of contact on crack growth rate is analyzed, and the fatigue crack growth life with and without contact is calculated. It is found that contact has some influence on crack growth rate and fatigue crack growth life. The residual life prediction process of the bolt connection structure is presented and the stress intensity factor with crack depth is predicted by the metabolic grey prediction model. The variation of crack growth rate with crack depth is further calculated. Finally, the fatigue residual life of suspension bolt connection structure is calculated. The finite element model of aircraft skin and long truss riveting connection is established. The modal analysis of the system is carried out, and the transient dynamics of the system is analyzed under different working conditions. The effects of contact and preloading forces on the dynamic characteristics of the system such as natural frequency are studied. It is found that the actual contact conditions have a significant effect on the dynamic characteristics of the whole system.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH131

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