二维二轴编织复合材料细观几何模型及拉伸模量研究

发布时间：2018-05-30 04:26

本文选题：二维二轴编织 + 细观几何模型　；参考：《东华大学》2017年硕士论文

【摘要】：为了更加合理有效地运用二维二轴编织铺层复合材料,需要模拟计算二维二轴编织铺层复合材料的各项具体拉伸性能指标,为此本文通过分析编织复合材料的细观结构特征,建立一套工程实用的二维二轴编织铺层复合材料单层和多层的细观几何结构模型和等效力学模型,并提出一套多层编织铺层复合材料拉伸模量的数值计算方法。最后结合拉伸断裂图像和拉伸实验数据分析复合材料拉伸断裂机理,通过研究二维二轴编织铺层复合材料拉伸断裂性质与结构的关系,总结出编织复合材料的拉伸断裂规律,进而更好地应用于实际生产。本课题研究借鉴前人对复合材料研究的理论基础。考虑到纤维屈曲是其模量损失的根本原因,结合实际编织复合材料的纱束横截面形态和屈曲起伏结构,还有编织工艺和固化工艺影响因素。提出模量损失等效观点,并建立二维二轴2×2编织结构组织单胞模型,纤维纱束起伏屈曲细观几何模型和相对应的等效力学模型。根据假设模型给出具体的数值计算方法。实验数据表明:由本文提出的屈曲损失模型和等效力学模型计算得出的有效模量数值高于目前文献计算精度,并且操作更简单。对于编织复合材料面内拉伸模量,参照分析前人的相关处理方法,本课题结合实际编织复合材料面内几何特征,考虑到实际的生产使用条件,假设等效编织复合材料为斜交对称铺层复合材料,应用其相关理论和方法,进行合理地面内正轴-偏轴转换,最终处理得到编织复合材料面内偏轴方向的有效拉伸模量数值。关于多层编织铺层复合材料,观察多层铺层间的几何结构,根据实际结构建立多弹簧并联模型,并根据力学模型推导出具体拉伸模量的数值计算方法,该方法简单易操作。最终实验数据结果表明:在拉伸模量数值变化趋势上计算值与实验值一致。具体数值结果上也吻合很好,表明假设模型的合理性和计算方法的有效性。对于编织铺层复合材料拉伸断裂机理,本课题结合实际拉伸数据和具体拉伸试样断裂破坏方式。分析阶段性拉伸断裂过程复合材料试样内部结构的变化,针对非常规破坏方式,结合具体试样给出了分析,对拉伸断裂破坏的一般性方式给出了较为客观的阐述,并分析了相关断裂破坏机理,为后续二维编织复合材料的拉伸断裂研究提供一定的理论依据。本课题主要采用理论分析法对二维编织复合材料进行拉伸模量研究,更多地考虑二维编织复合材料的生产条件和使用条件,建立的细观几何模型和等效力学模型更贴近实际情况。最终导出的计算方法建立起了二维编织复合材料宏观拉伸模量和细观结构与基础参数之间的桥梁关系,对实际二维编织复合材料的设计生产具有重要意义。
[Abstract]:In order to make more rational and effective use of two dimensional two axis braided laminated composites, it is necessary to simulate and calculate the specific tensile properties of two dimensional two axis braided laminated composites. In this paper, the microstructural characteristics of braided composites are analyzed. A set of engineering practical mesoscopic geometric structure model and equivalent mechanical model of single and multilayer braided composite materials are established, and a set of numerical calculation method for tensile modulus of multilayer braided laminated composites is presented. Finally, the tensile fracture mechanism of the braided composites is analyzed by combining the tensile fracture images and the tensile experimental data. The relationship between the tensile fracture properties and the structure of the braided composites is studied, and the tensile fracture law of the braided composites is summarized. Then it can be better applied in actual production. This research draws lessons from the previous research on the theoretical basis of composite materials. Considering that the fiber buckling is the fundamental reason of the modulus loss, combined with the actual braided composite yarn cross-section shape and buckling undulating structure, as well as the braiding process and curing process influence factors. The equivalent viewpoint of modulus loss is put forward, and the two-dimensional biaxial 2 脳 2 braided structure unit cell model, the mesoscopic geometric model of the undulating buckling of fiber bundles and the corresponding equivalent mechanical model are established. The numerical method is given according to the hypothetical model. The experimental data show that the effective modulus calculated by the buckling loss model and the equivalent mechanical model proposed in this paper is more accurate than that in the literature, and the operation is simpler. For the in-plane tensile modulus of braided composites, referring to the related treatment methods of the predecessors, this subject combines the in-plane geometric characteristics of the actual braided composites and takes into account the actual production and application conditions. Assuming that the equivalent braided composite is a skew symmetric laminated composite, the effective tensile modulus in the plane of braided composite is obtained by using the theory and method of the equivalent braided composite and the rational conversion between the positive axis and the offset axis in the ground. For the multilayer braided laminated composite material, the geometric structure between the layers is observed, and the multi-spring parallel model is established according to the actual structure. According to the mechanical model, the numerical calculation method of the specific tensile modulus is deduced. The method is simple and easy to operate. The final experimental data show that the calculated values are consistent with the experimental values in the trend of tensile modulus numerical variation. The numerical results are in good agreement with each other, which indicates the rationality of the hypothetical model and the validity of the calculation method. For the tensile fracture mechanism of braided laminated composites, this paper combines the actual tensile data and the fracture failure mode of concrete tensile specimens. This paper analyzes the internal structure change of the composite material during the stage tensile fracture process, analyzes the unconventional failure mode, combined with the concrete specimen, and gives a more objective exposition of the general mode of tensile fracture failure. The fracture failure mechanism is analyzed, which provides a theoretical basis for the further study of tensile fracture of two-dimensional braided composites. In this paper, the tensile modulus of two-dimensional braided composites is studied by theoretical analysis, and the production and application conditions of two-dimensional braided composites are considered more. The mesoscopic geometry model and equivalent mechanics model are more close to the actual situation. The calculated method established the bridge relationship between the macroscopical tensile modulus of two-dimensional braided composites and the meso-structure and foundation parameters, which is of great significance to the design and production of two-dimensional braided composites.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33

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