CFRP材料孔隙缺陷特征分布理论与实验研究

发布时间：2018-03-27 04:53

本文选题：CFRP复合材料　切入点：孔隙率　出处：《哈尔滨工业大学》2015年硕士论文

【摘要】：CFRP复合材料由于具有许多非常优异的性能,在大型飞行器设计和制造中受到了广泛的重视,在航空航天飞机及其构件中的应用和所占的比重也相当可观。然而,复合材料构件自身的结构和组织形成原理导致碳纤维增强树脂基复合材料在制造和使用过程中会产生诸如孔隙、分层等缺陷,这些缺陷在承载和服役过程中,随着周围环境的改变也会相应发生扩展和转移。这对于大型飞机的使用和服役过程是一个巨大的安全隐患。高精度和高效率的无损检测与多维准确表征系统便是当务之急。然而,大尺寸复合材料构件制造缺陷和损伤的感知和表征极其困难,也对目前常规的无损检测方法造成了很大的困难。要想准确及高效地检测CFRP复合材料构件中的缺陷和分层,除了研究多尺度缺陷和损伤的高效无损检测原来和表征方法之外,还有一个十分重要的方面便是深入研究分析复合材料中缺陷和损伤的产生机理与扩展行为,并科学评价缺陷和损伤对各项性能的影响。本文利用统计、计算和模拟碳纤维增强树脂基复合材料在固化过程中各个参数变化的质变和量变过程,得到复合材料在制备过程中的固化温度、固化压强、固化率、粘度、表面张力/界面能、饱和溶解度等直接影响固化过程和气孔形成和生长的各个参数随着固化反应进行而产生的质变曲线和量变方程式。得到了固化过程中气泡的临界形核尺寸变化规律:随着溶解度下降和扩散反应加剧,气泡的临界形核尺寸呈上升趋势,气泡的形核最小形核尺寸为8μm;也得到了气泡临界生长尺寸公式,公式中R*与P基本上呈反比关系。气泡通过生长可以达到的最大尺寸为23μm,加压之后气孔半径缩小到4μm左右。固化过程中单个气泡的生长过程为:9 min时气泡开始形核,从10 min开始,气孔以一定速率成长并最终达到稳定。此外,本文通过CT法研究不同尺寸孔隙的数量发现:射线CT法得到的孔隙沿着纤维方向在树脂内部分布,1μm分辨率条件下,材料中碳纤维成分占66.79 vol.%,树脂成分占32.08 vol.%,孔隙成分占1.13 vol.%;7μm分辨率条件下,射线CT法得到数据显示碳纤维成分占67.08 vol.%,树脂成分占32.79vol.%,孔隙成分占0.84 vol.%。与1μm孔隙率1.13 vol.%相比,7μm的孔隙率略小。研究得到不同尺寸孔隙数量呈幂指数规律分布,越小的气孔数量越多。通过本课题的研究,可以为碳纤维增强树脂基复合材料的微观、细观和宏观表征技术提供借鉴,获得复合材料制备过程中造成缺陷和损伤的产生机理和扩展行为数据。这对于以后研究多尺度复合材料典型缺陷损伤,开展大型复合材料制造缺陷和损伤研究,确定缺陷损伤的物理和几何表现形式等具有重要意义。为航空航天飞机中大型复合材料构件缺陷和损伤的高精度高效率无损检测原理和方法的研究奠定了一定的基础。
[Abstract]:Because of its many excellent properties, CFRP composite materials have been paid more and more attention in the design and manufacture of large aircraft, and the application and proportion in the space shuttle and its components are also considerable. The structure and microstructure of composite components lead to defects such as porosity, delamination and so on in the process of manufacture and use of carbon fiber reinforced resin matrix composites, which are in the process of carrying and service. As the surrounding environment changes, it will expand and shift accordingly. This is a huge security hazard for the use and service of large aircraft. The high precision and high efficiency nondestructive testing and multidimensional accurate representation system are. As a matter of urgency... however, It is very difficult to detect and characterize defects and damage in large scale composite components, which also makes it difficult to detect defects and delamination in CFRP composite components accurately and efficiently. In addition to studying the original and characterization methods of high efficient nondestructive testing for defects and damage in multi-scale, it is also very important to deeply study and analyze the mechanism and propagation behavior of defects and damage in composite materials. The effects of defects and damage on the properties were evaluated scientifically. In this paper, the qualitative and quantitative changes of the parameters of carbon fiber reinforced resin matrix composites during curing were calculated and simulated by means of statistics. The curing temperature, curing pressure, curing rate, viscosity, surface tension / interfacial energy of the composite were obtained. Saturation solubility and other parameters directly affecting the curing process and the formation and growth of pores are the qualitative change curves and the quantitative equations resulting from the curing reaction. The critical nucleation size variation gauge of the bubble during the curing process is obtained. Law: as the solubility decreases and the diffusion reaction intensifies, The critical nucleation size of bubbles tends to increase, and the minimum nucleation size of bubbles is 8 渭 m. The maximum size of bubble through growth is 23 渭 m, and the pore radius is reduced to about 4 渭 m after compression. The growth process of a single bubble during solidification is: 9: 9 min, when the bubble begins to nucleate, the maximum size of the bubble is 23 渭 m, and the pore radius is reduced to about 4 渭 m after compression. From 10 min onwards, the pores grew at a certain rate and finally reached stability. In addition, the number of pores of different sizes was studied by CT. The results showed that the pores obtained by X-ray CT were distributed in the resin at a resolution of 1 渭 m along the fiber direction. Carbon fiber is 66.79 vol.%, resin is 32.08 vol., pore is 1.13 vol. at 7 渭 m resolution. The data obtained by X-ray CT showed that carbon fiber composition was 67.08 vol.%, resin composition was 32.79 vol.%, pore composition was 0.84 vol..Compared with 1 渭 m porosity 1.13 vol.%, the porosity of 7 渭 m was slightly smaller. The smaller the number of pores, the more. Through the study of this topic, we can provide a reference for the microscopic, microcosmic and macroscopic characterization of carbon fiber reinforced resin matrix composites. The formation mechanism and spreading behavior data of defects and damage caused by composite materials were obtained, which can be used to study the typical defects of multiscale composite materials and to study the manufacturing defects and damage of large composite materials. It is of great significance to determine the physical and geometric forms of defect damage, which lays a foundation for the study of the principles and methods of high precision and high efficiency nondestructive detection for the defects and damage of large composite components in the space shuttle.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：V250

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