机翼上表面处机身附属装置
目录
摘要III
Abstract IV
第一章绪论1
1.1研究背景1
1.2MED剩余强度分析国内外现状2
1.3本文主要内容3
第二章MED剩余强度分析理论1
2.1广布疲劳损伤敏感结构1
2.2应力强度因子3
2.2.1裂纹模型4
2.2.2计算应力强度因子的几种基本方法4
2.3相互影响因子7
2.4剩余强度理论8
2.4.1平均应力准则9
2.4.2净截面屈服准则10
2.4.3塑性区连通准则11
2.4.4断裂力学准则13
2.5本章小结13
第三章有限元建模14
3.1ABAQUS软件介绍14
3.2ABAQUS验证14
3.2.1验证模型14
3.2.2输出值比较15
3.3建模过程16
3.3.1模型尺寸以及材料参数17
3.3.2abaqus仿真建模18
3.4有限元计算和结果分析27
3.4.1桁架应力和位移的云图27
3.4.2应力强度因子结果曲线图30
3.4.3相互影响因子分析33
3.4.4剩余强度分析35
3.5本章小节40
第四章结束语41
4.1本文的主要贡献41
4.2需要进一步研究的问题41
参考文献42
致谢44
MED剩余强度分析
摘要
结构疲劳损失形式WFD(广布疲劳损失)是在Aloha事件之后，开始广泛出现在人们的视野中。目前实验已表明飞机在长期的飞行过程中，由于疲劳载荷等内部与外部原因会在结构上产生多部位损伤（MSD）与多元件损伤（MED）,这两种损伤会导致飞机结构的剩余强度迅速降低，严重情况下会在飞行过程中产生严重的事故。本文主要针对飞机结构进行多元件损伤的研究与分析，重点对裂纹尖端应力强度因子，相互影响因子、以及剩余强度等方面进行了研究。
本文给出了获得多元件裂纹尖端应力强度因子的有限元分析计算过程，对典型的飞机蒙皮与桁架连接处铆钉孔的裂纹进行模拟计算，获得了裂纹开裂状态下裂纹尖端处多元件相互影响因子的数值拟合结果。在此基础，通过进一步计算分析，利用净截面屈服准则，塑形区连通准则等判据得出含多元件损伤结构的剩余强度，最终结果表明多元件损伤对结构剩余强度有显着的影响。因此在结构损伤容限评定中，对多裂纹损伤结构应当予以重视，从而为飞机结构的安全提供保障。
关键词：广布疲劳损伤;多元件损伤;多元件相互影响因子;剩余强度;应力强度因子
The analysis of residual strength of MED
Abstract
After the Aloha incident, a new form of structural fatigue damage (WFD) appeared in people's field of vision. During long-term flight, the aircraft will suffer multiple structural damages due to internal and external causes such as multiple site damage (MSD) and multiple element damage (MED), which can lead to a rapid decrease in the remaining strength of the aircraft structure,which may also cause serious accidents during the flight. It is very important to predict and study multiple site damage and multiple element damage. This paper mainly focuses on the research and analysis of multiple element damage of aircraft structure, focusing on two aspects of the influence factors of crack tip and residual intensity.
In this paper, the finite element calculation process for obtaining multiple element influencing factors is presented. The cracks in the rivet holes at the junction of a typical aircraft skin and truss are simulated and calculated. Through this way, the numerical simulation of multiple element interaction factors at the crack tip in crack cracking state is obtained. On this basis, through further calculations and analysis, the residual intensity of multiple element crack structures is obtained, by using criteria such as the net section yield criterion and the shaping zone connectivity criterion. The results show that the mutual influence between multiple element damages is significant for the residual intensity of the structure. In the evaluation of structural damage tolerance, more attention should be paid to the damage of multiple cracks, so as to guarantee the safety of the aircraft structure.
Key words: widespread fatigue damage; multiple element damage; multiple element interaction factor ; residual strength ; stress intensity facto
设计所包含文件
字数统计
尾部气密框处的蒙皮拼接
腹板或蒙皮厚度突变—气密或非气密结构
机身舷窗周围结构
