复合材料T型接头界面增强设计方法研究

发布时间：2018-10-31 14:28

【摘要】：T型接头是一种应用于现代飞机结构的整体化复合材料典型结构形式。蒙皮与缘条之间界面的脱胶是T型接头的典型失效模式。通过Z-pin增强技术能够显著提高蒙皮与缘条的界面性能。本文采用商业有限元软件ABAQUS建立Z-pin增强模型,研究Z-pin对复合材料T型接头性能的影响,主要内容如下:1.介绍了基于内聚力模型的粘聚接触模拟方法,分别采用二次的名义应力强度准则来预测接触面脱胶的起始,采用混合型能量释放率准则来预测界面脱胶的扩展。介绍了基于细观力学的Z-pin桥联律计算方法,通过与试验数据的比较,确定该方法计算Z-pin张开型桥联律与剪切型桥联律的准确性。2.建立拉脱载荷下复合材料T型接头的三维有限元模型,通过定义粘聚接触来模拟界面的脱胶,采用与细观力学方法相结合的非线性弹簧元模拟Z-pin的增强效果。分析结果与试验吻合较好,验证了粘聚接触模拟界面破坏及非线性弹簧模拟Z-pin增强机制的可靠性。在此基础上建立了拉脱载荷下复合材料T型接头的二维有限元模型,界面及Z-pin的模拟方法与三维模型相同。二维的分析结果与试验吻合较好,从而为Z-pin增强的参数化分析作准备。3.建立侧弯载荷下复合材料T型接头的三维有限元模型,通过Ufield子程序加入三维Hashin失效判据,建立刚度退化模型。研究了复合材料T型接头在侧弯载荷下受压侧缘条材料的损伤对其承载能力降低的影响,得到缘条区的Z-pin增强较难提高复合材料T型接头侧弯承载能力的结论。4.采用二维模型进行了各Z-pin参数对复合材料T型接头拉脱承载能力影响的参数化分析,深入地研究了各参数及Z-pin布置位置的影响,并提出了设计建议。
[Abstract]:T-joint is a typical integral composite structure used in modern aircraft structures. The degumming of the interface between the skin and the edge strip is the typical failure mode of T-joint. The interfacial properties of skin and fringes can be significantly improved by Z-pin enhancement technique. In this paper, the commercial finite element software ABAQUS is used to establish the Z-pin reinforcement model, and the effect of Z-pin on the properties of T-joints is studied. The main contents are as follows: 1. In this paper, the cohesive contact simulation method based on cohesive force model is introduced. The quadratic nominal stress intensity criterion is used to predict the initial degumming of the contact surface, and the hybrid energy release rate criterion is used to predict the expansion of the interface degumming. The calculation method of Z-pin bridge law based on mesomechanics is introduced. By comparing with the experimental data, the accuracy of this method in calculating Z-pin open bridge law and shear bridge law is determined. 2. A three-dimensional finite element model of T-joints of composite materials under pull-off loading was established. The interface degumming was simulated by defining cohesive contact, and the enhancement effect of Z-pin was simulated by nonlinear spring element combined with meso-mechanical method. The analytical results are in good agreement with the experimental results, which verify the reliability of the cohesive contact simulation interface failure and the nonlinear spring simulation Z-pin reinforcement mechanism. On the basis of this, a two-dimensional finite element model of composite T-joint under tension and detach load is established. The simulation method of interface and Z-pin is the same as that of 3D model. The results of two-dimensional analysis are in good agreement with the experimental results, thus preparing for the parameterized analysis enhanced by Z-pin. 3. Three-dimensional finite element model of composite T-joint under lateral bending load was established. The stiffness degradation model was established by adding three-dimensional Hashin failure criterion into Ufield subroutine. In this paper, the effect of damage on the load carrying capacity of composite T-joints under lateral bending loading is studied. The conclusion that Z-pin strengthening in the edge zone is difficult to improve the lateral bending capacity of T-joints is obtained. 4. The effects of Z-pin parameters on the tensile load capacity of composite T-joints are analyzed by using a two-dimensional model. The effects of each parameter and the location of Z-pin arrangement are studied in depth, and some design suggestions are put forward.
【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】：2015
【分类号】：V214.8

【相似文献】