三维六向编织复合材料力学性能及其参数反演分析

发布时间：2018-03-07 18:50

本文选题：三维六向编织复合材料　切入点：力学性能试验　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：三维六向编织复合材料是在三维四向编织预成型体的基础上,分别在纵向和横向上添加不动纱而形成的一种整体结构性能良好的编织结构,因其除了具有高比刚度、高比强度的优点之外,在面外性能、剪切性能、结构可设计性等方面表现优异,故在航空航天领域应用前景广阔。但研究其力学行为的文献报道较少,仅有的研究主要针对的是不同编织角、不同纤维体积分数对材料拉伸或连接性能的影响,这是设计阶段材料选型和使用过程中工艺要求所需要的,但作为一种典型的正交各向异性和拉压双模量复合材料,在设计和使用阶段,还需重点考虑材料在不同工况下、不同方向上的力学性能差异,此外,针对材料刚度的预报,目前还缺乏与真实细观结构观测结果的结合和考虑拉压不同性能,而且借鉴于纤维增强层合板相关实验标准,对材料进行性能测试,面临实验工作量大、周期长、效率低、费用高等困难,且在不同类型的实验之间,由于试样形状不一和复合材料数据的离散性,在对数据进行横向比较方面存在一定难度,急需发展一种一次实验测出多个力学性能参数的方法。因此,针对上述存在的不足和困难,本文主要进行以下三个方面的研究。首先对小编织角、中等纤维体积含量的T300/TDE86三维六向编织复合材料进行了不同工况下、不同方向上的力学性能试验,包括:纵向拉伸、三个不同方向上的压缩和面内剪切性能试验,获得了相应的强度和模量等数据,以及破坏模式与损伤机制,并详细横向比较了它们之间的异同及原因。其次在四步法编织工艺的基础上,对原始材料和烧去树脂后的材料进行了不同方位上不同纱线走向的观测,确定了材料的细观结构形式和特征参数,以及纱线之间的扭结、接触情况,在一定假设条件的基础上,考虑到材料宏观实际尺寸,建立了厚度方向上的全尺寸几何分析模型,采用已有文献关于纤维束和基体的组分材料力学性能参数,利用刚度组装技术对几何分析模型进行了不同方向上的刚度预报,预报结果与实验数据相比,除厚度方向压缩性能和面内剪切刚度误差较大外,其余吻合均较好,说明了本章刚度预报方法的准确性;最后联合使用数字图像相关技术(DIC)和有限元对三维六向编织复合材料的开孔试样在拉伸条件下进行了真实应变场和模拟应变场之间的误差分析,并搭建了优化更新平台,以支反力为约束条件,应变场误差为目标函数,采用单纯形法对四个面内性能参数为设计变量进行了优化,收敛结果与相应试验测试数据吻合较好,说明了该平台的可行性。
[Abstract]:Three-dimensional six-direction braided composite material is a kind of braided structure with good structural performance based on three-dimensional four-direction braided preform, which is composed of longitudinal and lateral immobility yarn respectively, because of its high specific stiffness. In addition to the advantages of high specific strength, it has excellent performance in such aspects as out-of-plane properties, shear properties and structural designability, so it has a broad application prospect in the field of aeronautics and astronautics, but there are few reports on its mechanical behavior. The only research focuses on the effects of different braiding angles and fiber volume fraction on the tensile or bonding properties of the material, which is required by the process requirements in the process of material selection and use in the design phase. However, as a typical orthotropic and tension-compression composite, in the design and application stage, it is necessary to consider the difference of mechanical properties of the material in different working conditions and in different directions. In addition, the prediction of the stiffness of the material is carried out. At present, there is a lack of combination with the observation results of real meso-structure and consideration of different properties of tension and compression, and the performance of the material is tested by referring to the relevant experimental standards of fiber reinforced laminates, which is faced with a large amount of experimental work, a long period and low efficiency. The cost is high, and it is difficult to compare the data horizontally between different types of experiments because of the different shapes of samples and the discreteness of composite material data. There is an urgent need to develop a method for measuring multiple mechanical properties in one experiment. Therefore, in view of the shortcomings and difficulties mentioned above, this paper mainly studies the following three aspects: firstly, for the small braiding angle, T300 / TDE86 3D hexagonal braided composites with medium fiber volume content were tested in different directions under different working conditions, including longitudinal tensile tests, compression tests in three different directions and in-plane shear tests. The corresponding data such as strength and modulus, failure mode and damage mechanism are obtained, and the similarities and differences between them and their causes are compared in detail. Secondly, on the basis of the four-step braiding process, The original material and the material after burning resin were observed in different directions, the meso-structure and characteristic parameters of the material were determined, as well as the kink and contact between the yarns. On the basis of certain assumptions, Considering the actual size of material, a full-scale geometric analysis model in thickness direction is established. The mechanical properties of fiber bundle and matrix are used. The stiffness prediction of the geometric analysis model in different directions is carried out by means of stiffness assembly technique. Compared with the experimental data, the predicted results are in good agreement with the experimental data except that the compression performance in the thickness direction and the in-plane shear stiffness error are larger. The accuracy of the stiffness prediction method in this chapter is explained. Finally, the error analysis between the real strain field and the simulated strain field of 3D hexagonal braided composites under tensile condition is carried out by using the digital image correlation technique (DIC) and finite element method, and the optimization updating platform is built. The four in-plane performance parameters are optimized by simplex method with the support reaction force as the constraint condition and the strain field error as the objective function. The convergence results are in good agreement with the corresponding test data, which shows the feasibility of the platform.
【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】：TB332

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