碳纤维复合材料机械连接载荷分配均匀化研究

发布时间：2018-02-14 09:09

本文关键词： 复合材料机械连接载荷分配影响因素均匀化　出处：《上海交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：航空复合材料结构中存在着大量机械连接结构,机械连接对飞机结构的效率和安全至关重要。在复合材料多钉螺栓连接中,由于复合材料本身没有塑性区会造成载荷分配的严重不均。研究复合材料机械连接载荷分配不均分析其均匀化策略与策略,可以提高复合材料机械连接的整体强度,提高连接效率。本文采用三维有限元数值仿真和实验研究的方式来开展碳纤维复合材料螺栓连接载荷分配的均匀化研究。首先查阅资料设计了复合材料机械连接的几何参数,并使用ABAQUS有限元分析元件建立了复合材料多钉连接的三维有限元模型,通过单钉和多钉连接证实了多钉连接载荷分配存在的不均现象。之后,使用表面应变计电测法对复合材料机械连接的载荷分配问题开展了实验研究,将实验与有限元结果对比分析,验证了有限元模型的有效性。提出了针对多钉螺栓连接的载荷不均匀度的概念,配合三维有限元模型进行了载荷分配的参数化研究,探究了预紧力、间隙、干涉、板间摩擦力,几何参数等因素对复合材料螺栓连接载荷分配的影响,发现间隙和干涉都会强烈影响载荷分配比例,而板间摩擦力、预紧力、几何参数对载荷分配的影响较小。间隙和干涉对载荷比例的影响都是通过改变初始承载比例实现的,且承载比与间隙量的大小呈近似负线性相关;在孔径的0.75%以下时,承载比与干涉量呈负相关关系;干涉量超过孔径的0.75%后对承载比不再有影响。之后进行了影响因素的多因素研究,发现干涉与间隙同时作用能以更小的间隙(干涉)量使载荷均匀化。在此基础上总结了载荷均匀化策略,最实用的策略为综合使用干涉与间隙配合,在大载荷处使用适量的间隙配合,在小载荷出使用少量的干涉配合,切间隙量和干涉量都不宜过大,干涉量/孔径在0.5%~0.75%之间,间隙量/孔径在0.5%左右为宜。
[Abstract]:There are a large number of mechanical connections in aeronautical composite structures, which are of great importance to the efficiency and safety of aircraft structures. Due to the fact that there is no plastic zone in the composite material itself, the load distribution will be seriously uneven. The study on the uniform strategy and strategy of mechanical joint load distribution can improve the overall strength of the mechanical joint of composite material. In this paper, three-dimensional finite element numerical simulation and experimental study are used to study the load distribution of carbon fiber composite bolt connection. Firstly, the geometric parameters of mechanical connection of carbon fiber composite are designed with reference to the data. The three-dimensional finite element model of composite multinail connection is established by using ABAQUS finite element analysis element. The uneven distribution of load in multinail connection is proved by single nail and multi-nail connection. The load distribution of mechanical joints of composite materials is studied experimentally by using the electrical measurement method of surface strain gauges. The results of the experiments are compared with those of the finite element method. The validity of the finite element model is verified. The concept of load unevenness of multi-nail bolt connection is proposed, and the parameterized study of load distribution is carried out in conjunction with the three-dimensional finite element model, and the pretightening force, clearance, interference and friction between plates are explored. The effect of geometric parameters on load distribution of composite bolt joint shows that clearance and interference will strongly affect the load distribution ratio, while the friction and preload between plates, The influence of geometric parameters on load distribution is small. The effect of clearance and interference on load ratio is achieved by changing the initial load ratio, and the bearing ratio is approximately negative linear correlation with the magnitude of clearance, and when the aperture is below 0.75%, The bearing ratio is negatively related to the interference, and the interference is no longer affected by the aperture of 0.75%, and then the multi-factor study of the influencing factors is carried out. It is found that the interaction between interference and clearance can homogenize the load with smaller clearance (interference). Based on this, the strategy of load homogenization is summarized. The most practical strategy is the comprehensive use of interference and clearance coordination. When the appropriate amount of clearance fit is used at large load and a small amount of interference fit is used at small load, the amount of cutting gap and interference amount should not be too large, the interference amount / aperture is between 0.75% and 0.5% or so.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：V258.3

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