【作者】 彭峰；

【导师】 胡德安； 陶剑波；

【作者基本信息】 湖南大学 ， 车辆工程（专业学位）， 2018， 硕士

【摘要】 随着航天、汽车等领域的快速发展,结构性能相当于或优于铝合金的先进复合材料开始兴盛,由于复合材料的诸多优异性能,一经问世就显示了巨大的生命力。复合材料连接结构的主要连接形式是机械连接以及胶接连接,其中机械连接是最主要的连接形式。机械连接的质量易于控制、强度分散性小、能传递大载荷、便于装卸、安全可靠,但是由于开孔引起应力集中,削弱复合材料结构的承载能力。同时由于复合材料结构抗冲击能力非常弱,因此在低速冲击载荷作用下,通过数值模拟的方式研究各种关键因素对复合材料机械连接力学性能特性的影响规律很有必要。本文首先介绍了复合材料的本构模型包括二维Hashin失效准则以及复合材料层间损伤模型,在此基础上利用ABAQUS建立了碳纤维复合材料层合板单剪单钉连接模型和碳纤维复合材料层合板低速冲击有限元模型,分别模拟碳纤维复合材料层合板单剪单钉连接在静拉伸载荷作用下的力学响应以及碳纤维复合材料层合板在低速冲击载荷作用下的力学响应,通过试验结果的对比,验证了机械连接模型以及材料参数的有效性。其次利用ABAQUS建立了碳纤维复合材料单剪双钉和单剪四钉连接有限元模型,并分析了在低速冲击载荷作用下单向铺层比例、层合板的板宽、单向铺层夹角对于单剪双钉连接层合板连接性能的影响以及连接区面积、钉的排列方式对单剪四钉连接层合板连接性能的影响,结果表明板宽、单向铺层夹角以及单向铺层比例对碳纤维复合材料层合板单剪双钉连接性能均有显著影响,而菱形的排列方式更有助于提升单剪四钉层合板连接性能。最后分析了不同螺栓-孔配合作用下孔周径向应力的分布情况,进一步分析了在低速冲击载荷作用下干涉配合和螺栓预紧力混合作用以及配合方式对碳纤维复合材料单剪双钉连接性能的影响,结果表明干涉量和预紧力的大小均会影响复合材料结构的连接性能,但是预紧力的影响程度大于干涉量,通过研究间隙配合和干涉配合两种配合方式对碳纤维复合材料层合板单剪双钉连接性能的影响,结果表明配合方式对孔周径向应力的分布有显著影响,同时对连接性能也有影响,但对连接破坏模式没有影响。更多还原

【Abstract】 With the rapid development of aerospace,automobile and other fields,the advanced composite materials have begun to flourish,the structural properties are equivalent or superior to aluminum alloy.Because of the excellent properties of the composites,they have shown great vitality once they come out.The joint of composite material structure mainly includes mechanically fastened joints and adhesively bonded joints.Mechanically fastened joints is one of the most important forms of the composite structure.The mechanically fastened joints quality is easy to control,low intensity dispersion,can transmit more load,for convenient handling,safe and reliable.However,due to the opening of the hole,the fibre would be cut off during production processes,it will bring stress concentration,weaken the bearing capacity of composite material structure.Meanwhile due to the impact resistance of the composite materials is very weak,so under low velocity impact loads,It is necessary to research the effects of mechanical properties of composite structures all the above critical factors by numerical simulation.First of all,introduces the constitutive model of composite material including two dimensional Hashin failure criterion and composite layer damage model.On this basis,the static tensile model of single-lap bolted joint of carbon fiber composite laminates and the low velocity impact loads finite element model of carbon fiber composite laminates are established by using ABAQUS,the mechanical response of the single-lap bolted joint of carbon fiber composite laminates to the static tension load and the mechanical response of the carbon fiber composite laminates under the low velocity impact loads respectively,the simulation results match well with experimental data,which verifys the accuracy of the modeling method and material parameters.Then,the finite element model of single-lap double bolted joints and single-lap four bolted joints of carbon fibre copmosite are established by using ABAQUS,analyse the effects of geometrrical parameters,unidirectional laminate angle,unidirectional plies ratio on joint properties of double bolted joints and a study was carried out to investigate the joint properties effects of joining region and arrange styles of pins about four bolted joints under the low velocity impact loads.The resultsshow that the geometrrical parameters,the unidirectional laminate angle and the unidirectional plies ratio have significant influence on the joint properties of the single-lap double bolted joints of carbon fiber composite laminates,and the arrangement of the rhombus is more helpful to improve the connection performance of the single-lap four bolted joints of carbon fiber composite laminates.Finally,analyse the circumferential radial stress under different bolts-holes fit,research the influence of mechanical joint properties of connection hole interference and bolt pretightening force and two set of composite-to-titanium single-lap bolted joints under the low velocity impact loads.The results show that the size of interference and pretightening force will affect the connection performance of the composite structure,but the influence of pretension is greater than the interference.and the two set of composite-to-titanium single-lap bolted joints have significant effect of the circumferential radial stress and meanwhile have effect of the single-lap double bolted joints of connection properties of carbon fiber composite laminates,but it has no effect of the failure mode.更多还原