【作者】 曹海建；

【导师】 魏取福； 钱坤；

【作者基本信息】 江南大学 ， 纺织工程， 2010， 博士

【摘要】 三维机织整体中空复合材料是一种新型夹芯结构材料,国外称之为三明治结构。该材料主要由100%的E-Glass纤维织造而成,其三明治结构通过Z向纤维整体连接织物的上、下2个层面,其典型空间特征是芯部沿经向呈现出“8”字形,沿纬向呈现出“I”字形。三维机织整体中空复合材料具有优异的整体性能,克服了传统蜂窝、泡沫等夹芯复合材料易分层、耐冲击性能差的缺点,目前已广泛应用于大面积船身、机翼、油罐的夹层、各种地板、隔墙等。迄今为止对三维机织整体中空复合材料的研究主要集中在基本力学性能、低速冲击等实验研究上,而对整体中空织物的制备、结构参数对材料力学性能与低速冲击的影响、低速冲击后材料剩余强度,以及材料的结构理论等方面研究甚少。本课题在成功制备三维机织整体中空复合材料的基础上,对材料的力学性能、低速冲击性能、结构理论研究等方面作了较为详细的研究。论文主要工作包括：(1)三维机织整体中空复合材料的制备。第一步,设计不同类型的整体中空织物,包括“8”字形、“88”字形、2.5维整体中空织物等。第二步,整体中空织物的织造,包括工艺调整、织造生产等。第三步,树脂基体的制备。选取树脂(环氧618)、固化剂(聚酰胺651)、稀释剂(环氧丙烷丁基醚660)等组成树脂基体,配比为100：50：30。第四步,整体中空织物的复合成型。采用手糊成型、真空辅助成型等方式制备三维机织整体中空复合材料。(2)三维机织整体中空复合材料的力学性能研究。研究整体中空复合材料在平压、侧拉、侧压、剪切、弯曲等载荷作用下的力学特性,重点分析芯材高度、芯材密度等结构参数对材料力学性能的影响。结果表明：三维机织整体中空复合材料的平压、剪切等性能随着芯材高度的增加而减小；侧拉、侧压、弯曲等性能随着芯材高度的增加而增加；整体中空复合材料的平压、侧拉、侧压、剪切、弯曲等性能随着芯材密度的增加而增加。(3)三维机织整体中空复合材料的低速冲击性能研究。第一步,选取芯材高度为5mm的材料,分别进行1～10 J能量的低速冲击,研究材料的低速冲击特性；第二步,选取芯材高度分别为5、6、7mm的材料,进行8J能量的低速冲击,研究芯材高度对低速冲击性能的影响；第三步,选取芯材高度为7mm、铝蒙皮厚度为0.3 mm的材料,进行8 J能量的低速冲击,并将实验结果与未蒙皮的材料进行比较,研究蒙皮对低速冲击性能的影响。(4)三维机织整体中空复合材料低速冲击后剩余强度研究。第一步,选取芯材高度分别为5、6、7 mm的材料,进行8 J能量低速冲击,研究材料低速冲击后的剩余强度特性；第二步,选取芯材高度为7mm的材料,分别进行6、8、10J的能量冲击,研究冲击能量对低速冲击后剩余强度的影响；第三步,选取芯材高度为7mm、铝蒙皮厚度为0.3 mm的材料,进行8 J能量的低速冲击,测试材料的剩余压缩强度,并将实验结果与未蒙皮的材料进行比较,研究蒙皮对低速冲击后剩余强度的影响。(5)三维机织整体中空复合材料结构理论研究。利用有限元软件ANSYS,建立整体中空复合材料的结构模型,进行压缩力学特性分析。利用该模型,研究芯材高度、芯材密度、弹性模量、泊松比等结构参数对材料压缩性能的影响。结果表明：三维机织整体中空复合材料在受压状态下,芯材与上下面板相接处应力最大,最容易发生压缩破坏；材料的压缩强度随着芯材高度的增加而下降,随着芯材密度、泊松比的增加而增加；弹性模量对材料压缩性能的影响不大。更多还原

【Abstract】 The 3D woven integrated sandwich composites are new types of sandwich structure materials, which are also called sandwich structures in overseas. The 3D composites are mainly made of 100 percent of E-Glass fibers, and the sandwich structures are formed by the Z-direction fibers connecting the down and upper face-sheet of the fabrics. The typical spatial characteristics of the composites are that the piles show "8"-shape in warp direction, and " I "-shape in weft direction. The 3D composites have excellent integrated performance, which overcomes the weakness of easy delamination and poor impact resistance of the traditional sandwich structures, such as honeycomb and foam ones. Nowadays the 3D composites have been widely used in large areas of boats, aircraft wings, sandwich of oil tanks, various floors, and partition walls.So far the studies on the 3D composites have mainly focused on the experimental tests, such as the basic mechanical performance, low-velocity impact and other properties. However, the other studies on the 3D composites, such as the preparation of the 3D integrated sandwich fabrics, the effect of the structure parameters on the mechanical performance and low-velocity impact, the residual strength of the composites after low-velocity impact, and the structural theory of the composites, have not been properly studied.In the paper, the studies of the 3D composites on the mechanical performance, low-velocity impact, and structural theory were carried out in detail. The main work includes as follows.(1) The preparation of the 3D woven integrated sandwich composites. First step, the design of different types of 3D integrated sandwich fabrics, included "8"-shape, "88"-shaped, and 2.5D integrated sandwich fabrics. Second step, the weaving of the 3D sandwich fabrics, included processing adjustment, weaving production, and so on. Third step, the preparation of the resin matrix, which was made from the resin (epoxy resin 618), curing agent (PA 651), diluents (propylene oxide-butyl ether 660), and the ratio of the resin matrix is 100:50:30. Fourth step, the molding of the 3D integrated sandwich fabrics. In the paper, the method of hand lay-up molding and vaccum assisted resin infusion molding (VARIM) were used to prepare the 3D composites.(2) The studies of the mechanical properties on the 3D woven integrated sandwich composites.In the paper, the mechanical characteristics of the 3D integrated sandwich composite under flat compressive, side tensile, side compressive, shear and flexural loads were studied, and the effects of pile height and pile density on the mechanical properties were investigated too. The results indicated that the side tensile strength, side compressive strength and flexural strength increased, while the flat compressive strength and shear strength decreased with the increase of the pile height. The flat compressive strength, side tensile strength, side compressive strength, shear strength, and flexural strength all increased with the increase of the pile density. The results contribute to the optimal design of the 3D sandwich composites.(3) The studies of low-velocity impact behavior on the 3D woven integrated sandwich composites. First step, the low velocity impact characteristics of the 3D composites were investigated as a function of the pile height with 5mm under different impact energy from 1 to 10J respectively. Second step, the effects of pile height on low-velocity impact behavior were investigated as a function of the pile height with 5mm,6mm and 7mm under impact energy of 8J. Third step, the effects of covered skins on the low-velocity impact behavior were investigated by the comparison of behavior of the 3D composites that covered and uncovered with aluminum skins for 7mm.(4) The studies of residual strength on the 3D woven integrated sandwich composites after low-velocity impact. First step, the residual strength characteristics were investigated as a function of pile height with 5mm,6mm and 7mm under impact energy of 8 J. Second step, the effect of impact energy on the residual strength was investigated as a function of pile height with 7mm under impact energy of 6J,8J and 10J. Third step, the effects of covered skins on the residual strength were investigated by the comparison of behavior of the 3D composites that covered and uncovered with aluminum skins for 7mm.(5) The studies of structure theory on the 3D woven integrated sandwich composites. On the basis of previous studies, a new structural model was developed for the compressive analysis of 3D integrated sandwich composites by using the finite element software ANSYS. The effects of pile height, pile density, material elastic modulus and poisson ratio of the 3D composites on the compressive properties were studied in detail. The results show that the maximum value of the stress appears in the interface between pile and face-sheet when the 3D composites are subject under compressive loads, in which the composites damage easily. The compressive properties of the 3-D composites increase with the increase of the pile density, poisson ratio, and decrease with that of the pile height. The elastic modulus has little effect on the compressive properties of the composites. The results provide reference for the structure optimum of the 3D composites.更多还原