复合材料销钉连接的研究

发布时间：2019-01-30 21:22

【摘要】：随着复合材料应用的扩大,复合材料整体成型已经不能满足实际情况的需要,因此往往需要局部成型,并采用胶接或机械连接来组装。对于大型的受力构件,往往采用机械连接,需对复合材料制品进行打孔处理,由于复合材料是由两种不同性质的材料树脂基体与玻纤增强材料组成的,打孔处理会切断纤维,造成应力集中,并且在制孔过程中,树脂和纤维会发生分层现象,经研究发现复合材料的破坏主要发生在连接部位,因此研究复合材料的连接具有重要的意义。许多学者对复合材料机械连接的影响因素做了大量的工作,包括开孔尺寸,试样厚度,纤维铺层顺序,夹持力,装配间隙等。但是对于复合材料开孔方式的影响及表征的研究还比较少；另外复合材料开孔处往往需要补强,研究补强对其连接性能的影响具有重要的意义；不同制备工艺下,材料的性能也会不同,研究制备工艺对复合材料机械连接性能的影响,对于连接件的制备也具有重要的意义。本文研究了不同铺层顺序对销钉连接强度的影响。另外本文通过制备复合材料层间剪切试样,并采用两种制孔工艺对复合材料进行开孔处理,研究其对试样层间剪切强度的影响,进而研究不同开孔工艺对复合材料销钉连接强度的影响；本文还研究了在一定厚度下,补强面积对销钉连接强度的影响。此外,通过改变复合材料成型工艺,还研究了真空灌注工艺与手糊工艺对复合材料连接强度的影响。结果显示不同的铺层试样其破坏形式有所不同,在发生挤压形式破坏的同时,复合材料还伴随着其他形式的破坏,这是由于角度铺层的不同而引起的差异,45°层置于外层有助于复合材料销钉连接强度的提高。机械铣孔试样的层间剪切强度高于机械钻孔试样的层间剪切强度14%,表明机械钻孔对复合材料的损伤程度较大；采用扫描电镜对孔壁进行扫描,比较两种制孔工艺下孔壁的分层现象,观察发现,机械钻孔的孔壁能观察到明显的分层现象,而机械铣孔的孔壁的分层现象不明显,进一步证明了其销钉连接强度低于机械铣孔的复合材料连接强度,两者相差13%。研究还发现对复合材料开孔处进行补强增厚明显有助于复合材料连接强度的提高,能提高20%-50%,但开孔处补强面积并不是越大越好,对复合材料应力集中区域进行补强,确保破坏发生在补强区域内,而在试样破坏区域外增加补强面积,试样承载强度变化不大。在相同铺层层数的条件下手糊工艺制备的复合材料销钉连接强度却比真空灌注工艺制备的试样强度要高2.6%。
[Abstract]:With the expansion of the application of composite materials, the integral molding of composite materials can no longer meet the needs of the actual situation, so it is often necessary to form locally and assemble by glue or mechanical joints. For large mechanical members, mechanical connection is often used, and the composite products need to be perforated. Because the composite is composed of two different properties of the resin matrix and glass fiber reinforced material, the perforation treatment will cut off the fiber. The stress concentration and delamination of resin and fiber will occur in the process of making holes. It is found that the damage of composite mainly occurs in the joint position, so it is of great significance to study the bonding of composite materials. Many scholars have done a lot of work on the influencing factors of mechanical bonding of composite materials, including the size of opening, sample thickness, fiber layer sequence, clamping force, assembly clearance and so on. However, there are few studies on the influence and characterization of the opening mode of composite materials, in addition, the opening of composite materials often need to be reinforced, so it is of great significance to study the effect of reinforcement on the bonding properties of composites. The properties of the composites will be different under different preparation processes. It is also of great significance to study the effects of the preparation process on the mechanical bonding properties of the composites. In this paper, the influence of different layering order on pin joint strength is studied. In addition, through the preparation of interlaminar shear specimens of composite materials, two kinds of pore making processes were used to treat the composites, and the effect of the interlaminar shear strength on the interlaminar shear strength of the composites was studied. Furthermore, the influence of different hole opening processes on the bonding strength of composite pin is studied. The effect of reinforcement area on pin joint strength is also studied. In addition, the influence of vacuum casting and hand paste on the bonding strength of composites was studied by changing the molding process. The results show that the failure forms of different laminated specimens are different. While the extrusion failure occurs, the composites are accompanied by other forms of failure, which is caused by the difference of the angle layer. The 45 掳layer placed in the outer layer helps to improve the bonding strength of the composite pin. The interlaminar shear strength of machine-milling hole specimen is higher than that of mechanical borehole specimen, which indicates that the damage degree of mechanical borehole to composite material is great. Scanning electron microscope (SEM) was used to scan the hole wall and compare the delamination phenomenon of the hole wall under the two kinds of hole making technology. It was found that the hole wall of the mechanical drilling hole could be obviously stratified, but the stratification phenomenon of the hole wall of the machine milling hole was not obvious. It is further proved that the bonding strength of the pin is lower than that of the composite material with mechanical milling holes, and the difference between the two is 13%. It is also found that the reinforcement and thickening of the open hole of the composite can obviously contribute to the improvement of the joint strength of the composite, and can increase the strength of the composite by 20% -50, but the area of reinforcement at the opening is not the greater the better, and the stress concentration area of the composite is strengthened. It is ensured that the failure occurs in the reinforcement area, but the bearing strength of the specimen does not change much when the reinforcement area is increased outside the failure area of the specimen. The pin bonding strength of the composite prepared by the same layer-laying process is 2.6 higher than that of the sample prepared by the vacuum pouring process.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH131.6

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