【作者】 胡靖元；

【导师】 万志敏；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2010， 硕士

【摘要】 空间充气展开结构因为在通信和军事等方面的重要战略地位而备受关注,作为空间充气展开结构主要使用材料的织物复合材料,其研究工作也日益受到人们的重视。本文研究了固化后的空间充气展开结构材料(碳纤维织物和芳纶织物复合材料)的低速冲击破坏模式和损伤机理,考虑不同加载速率、材料自身特性参数(铺层数量和铺层方式)对低速冲击特性的影响,并针对低速冲击作用下的复合材料层合板建立三维有限元模型。研究表明,织物复合材料低速冲击破坏模式与增强纤维的性质有关:碳纤维织物复合材料在宏观上表现为脆性断裂模式,以纤维剪断为主,伴随沿织物方向的基体开裂以及基体与纤维脱粘,正面损伤区域近似圆形;芳纶织物复合材料呈现明显的以应力集中处为中心的十字形破坏区域,基体沿织物方向产生开裂,开裂处大量纤维拉伸断裂及拔出,纤维出现原纤化。失效过程分为四个阶段,但两种材料存在差异:碳纤维织物复合材料依次经历了弯曲变形、大量纤维断裂、穿透和扩孔阶段;而芳纶织物复合材料经历了弯曲变形、大量纤维断裂和拔出、穿透以及裂纹沿织物方向扩展阶段。织物复合材料的能量吸收过程包括初始阶段、线性增加阶段和稳定阶段,能量的吸收途径主要包括层合板的弯曲变形、纤维断裂和拔出、基体开裂、纤维与基体的脱粘以及分层等,纤维断裂是织物复合材料吸收能量的主要方式。织物复合材料的破坏模式和低速冲击响应受加载速率、铺层数量和铺层方式的影响。碳纤维织物复合材料的破坏模式和冲击响应与加载速率相关,表现出了明显的应变率效应,冲击速度的提高使得材料的抗穿透能力增强,芳纶纤维织物复合材料则对应变率不敏感;碳纤维织物和芳纶织物复合材料的抗冲击特性具有明显的厚度效应,随着铺层数量的增加,材料的能量吸收性能和抗冲击能力提高;铺层方式的研究表明,在设计抗冲击层合板时,要尽量避免具有相同方向铺层的铺层组,同时外表面优先选择(±45)铺层结构,并以(0,90)铺层居多为宜。基于显示有限元软件ABAQUS/Explicit和复合材料层合结构的力学模型,建立了冲击作用下的有限元分析模型;通过标准的拉伸试验,确定了碳纤维织物和芳纶织物复合材料的模型参数;结合复合材料Hashin失效准则和刚度退化技术对2.5m/s、3m/s和3.9m/s冲击速度下的碳纤维织物复合材料动态响应进行了有限元分析,所得的计算结果和实验结果吻合较好,证明所建模型的正确性。更多还原

【Abstract】 Inflatable space structures get more and more attention because of its superiority in the side of communications and military affairs. The woven fabric composites on the inflatable space structures are one of the most important materials. In this paper, low velocity impact failure modes and damage mechanism of cured woven fabric composites were studied. These woven fabric composites contain carbon woven fabric composites and aramid woven fabric composites. We focused on the failure modes and impact response characteristics of woven fabric composites as a function of impact velocity, material parameters (thickness and layer). To analyze the response of composite laminated plate under low-velocity impact, a finite element analysis model is established.Investigations show that the failure modes after low velocity impact are related to the nature of fiber. The failure modes of carbon woven fabric composites are brittle fracture which is dominated by fiber fracture following matrix cracking along the direction of fiber and interfacial debonding. The positive damage area is round. Aramid woven fabric composites obviously show a cross damage area which makes stress concentration as a center. This damage area has matrix cracking along the direction of fiber, fiber fracture and, aplit and fiber fibrillation. Faliure progress is divided into four stages. Two types of materials are different with each other. Carbon woven fabric composites experience overall bending, a large number of fiber fracture, penetrating and reaming. But aramid woven fabric composites contain overall bending, fiber fracture and aplit, penetrating and crack extension along the direction of fiber. The process of energy absorption contains three stages which are initial stage, linear stage and stable atege. The means of energy absorption contains overall bending, fiber fracture and aplit, matrix cracking and interfacial debonding, and they are dominated by fiber fracture.The failue modes and impact response are related to velocity, thickness and layer. The response of carbon fiber fabric reinforced epoxy resin composites is related to impact velocity. They have shown the strain rate sensitivity. The anti-penetrate capability of composites increases when the impact speed increases. The ability of energy absorption and impact resistance is increasing with the thickness, so thickness effect is significant. Layer is also one of the most important factors affecting the impact response characteristics. When designing the composite laminates, we should avoid having the same direction of the layer, and the surface must be (±45) layer. Also the proportion of (0,90) layer structure should be increased. The result also showed that internal damage area is larger than the surface after impacting.We establish the finite element model based on explicit finite element software ABAQUS/Explicit and the mechanical model of laminated structure. The material model parameters of carbon fiber fabric and aramid fabric composites are determined. The Hashin failure criteria and stiffness degradation are used to model the failure and response of composite material by comparing the computed results with the test data at the velocity of 2.5m/s, 3.0m/s and 3.9m/s. we can confirm that finite element analysis model is effective to analyze composite laminated plate under low velocity impact.更多还原