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《Composites Science and Technology》2007,67(3-4):471-480
The two-scale method (TSM) is successfully applied to the prediction for the mechanics parameters of 4-step three dimensional braided composites, including stiffness parameters and strength parameters. The two independent micro-structure parameters, the braiding angle and the fiber volume fraction, are investigated in this paper. Both of them are implicitly included in the fabric of the unit cell of 4-step braided composites with 1 × 1 pattern. They directly influence the strength of 4-step braided composites, including tensile strength, bending strength and torsion strength. And then, the curves of the strength along with the braiding angle and the fiber volume fraction are illustrated. By the comparisons with experimental data, the two-scale method is validated to predict the mechanics parameters of 4-step braided composite materials. 相似文献
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Xinrong Huang Ye Liu Wenfeng Hao Yinghua Liu Jianguo Zhu 《Applied Composite Materials》2018,25(1):163-176
The torsional bulking behavior of 3D 4-directional braided composites shafts was analyzed in this work. First, the unit cell models of 3D 4-directional braided composites shafts with different braiding angles and fiber volume fraction were built up. Then, the elastic parameters of 3D 4-directional braided composites shafts were predicted using the unit cells under different boundary conditions. Finally, the torsional bulking eigenvalues and bulking modes of the composites shafts were obtained by numerical simulation, and the effects of braiding angle and fiber volume fraction on the torsional bulking behavior of 3D 4-directional braided composites shafts were analyzed. The simulation results show that the bulking eigenvalues increase with the increase of braiding angle and fiber volume fraction. This work will play an important role in the design of 3D 4-directional braided composites shafts. 相似文献
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针对不同编织角度的三维四向编织碳纤维/环氧树脂复合材料,进行了热环境下的轴向拉伸和压缩力学性能实验研究,讨论了温度对三维四向编织复合材料的轴向拉伸和压缩力学性能的影响,并根据宏观断裂形貌和SEM图像分析了材料的破坏和断裂机制。结果表明,随着测试温度的升高,三维四向编织碳纤维/环氧树脂复合材料的纵向拉伸强度有小幅提高,而纵向压缩强度显著降低。在室温条件下,编织角对材料的纵向拉伸破坏特征没有影响,而对材料的纵向压缩破坏特征有较大影响。随着测试温度的升高,不同编织角度复合材料的纵向拉伸和压缩的损伤破坏形态均与室温条件下明显不同。 相似文献
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三维五向编织复合材料纵向性能的实验研究 总被引:9,自引:2,他引:9
通过对具有不同编织结构参数的三维五向编织复合材料试件的纵向拉伸和压缩实验,分析了该类材料的纵向拉、压刚度和强度随编织工艺参数的变化规律以及材料的失效形式.三维五向编织复合材料在破坏前基本保持线弹性,纵向拉、压破坏具有脆性特征,拉伸模量和压缩模量比较接近,但拉伸强度远大于压缩强度.编织角和纤维体积含量对材料性能的影响显著,纱线粗细的影响不大.提高第五向纱线的比例,可提高材料的纵向性能.此外,研究中采用短标距薄板试件,以避免试件产生整体屈曲和端部纤维束开裂破坏. 相似文献
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A new analytical model based on a multiunit cell model is proposed to predict the elastic properties of 3D full five-directional braided composites (F5DBC). The stiffness-volume averaging method is applied to predict the elastic properties of unit cell models in meso-scale and specimens in global-scale by using the multi-scale modeling procedures. The contribution of all unit cells to the elastic properties of specimen is considered in the analytical model. The predicted elastic properties are in good agreement with the available experimental data, demonstrating the applicability of the model. Also, the effects of the braiding angle and the fiber volume fraction on the elastic properties are discussed in detail. The elastic constants of each unit cell are analyzed and the effect of the number of yarn carriers on the mechanical properties is also investigated. Results indicate that it is convenient to apply the present analytical model to predict the elastic properties of 3D F5DBC due to high computational efficiency. 相似文献
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以修正的经典层合板理论为基础, 分析三维编织复合材料的力学性能。在单胞的长度方向积分和平均, 预测编织结构复合材料的有效弹性模量; 采用蔡-胡多项式失效准则, 得到三维编织复合材料的强度性能。另外, 进行编织结构复合材料的力学性能实验, 探讨纺织工艺参数, 如纤维编织角、横向编织角、轴向纱数与编织纱数之比、纤维体积含量等对力学性能的影响, 理论预报和试验结果进行对比, 发现该力学模型能较好地预报三维编织复合材料的刚度和强度性能。 相似文献
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建立了基于三细胞模型数值预报三维编织复合材料粘弹性能的方法。首先构造了三维编织复合材料的三细胞模型并施加周期性边界条件,随后利用标准线性固体模型模拟树脂基体的粘弹性能,导出基体的松弛模量,再通过有限元计算及Prony级数拟合,得到三种胞元的粘弹性参数。然后根据三种胞元的体积分数和粘弹性参数,利用三个标准线性固体模型并联,模拟得到三维编织复合材料沿编织方向的粘弹性参数和蠕变本构关系。最后,分析了编织角和纤维体积含量对粘弹性能的影响。 相似文献
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Diantang Zhang Li Chen Ying Sun Yifan Zhang Kun Qian 《Applied Composite Materials》2017,24(5):1233-1250
A study is conducted with the aim of developing multi-scale analytical method for designing the composite helicopter arm with three-dimensional (3D) five-directional braided structure. Based on the analysis of 3D braided microstructure, the multi-scale finite element modeling is developed. Finite element analysis on the load capacity of 3D five-directional braided composites helicopter arm is carried out using the software ABAQUS/Standard. The influences of the braiding angle and loading condition on the stress and strain distribution of the helicopter arm are simulated. The results show that the proposed multi-scale method is capable of accurately predicting the mechanical properties of 3D braided composites, validated by the comparison the stress-strain curves of meso-scale RVCs. Furthermore, it is found that the braiding angle is an important factor affecting the mechanical properties of 3D five-directional braided composite helicopter arm. Based on the optimized structure parameters, the nearly net-shaped composite helicopter arm is fabricated using a novel resin transfer mould (RTM) process. 相似文献
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Dian-sen Li Dai-ning Fang Zi-xing Lu Zhen-yu Yang Nan Jiang 《Applied Composite Materials》2010,17(4):389-404
In the first part of the work, we have established a new parameterized three-dimensional (3D) finite element model (FEM) which
precisely simulated the spatial configuration of the braiding yarns and considered the cross-section deformation as well as
the surface contact relationship between the yarns. This paper presents a prediction of the effective elastic properties and
the meso-scale mechanical response of 3D braided composites to verify the validation of the FEM. The effects of the braiding
parameters on the mechanical properties are investigated in detail. By analyzing the deformation and stress nephogram of the
model, a reasonable overall stress field is provided and the results well support the strength prediction. The results indicate
it is convenient to predict all the elastic constants of 3D braided composites with different parameters simultaneously using
the FEM. Moreover, the FEM can successfully predict the meso-scale mechanical response of 3D braided composites containing
periodical structures. 相似文献
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基于三维四向和五向编织复合材料的细观结构和单胞模型, 对三维四步法矩形截面编织复合材料悬臂梁的振动阻尼性能进行了理论分析, 研究了编织角、 纤维体积分数等工艺参数对材料振动阻尼特性的影响, 并与实验结果进行了对比。对三细胞模型进行了改进, 采用混合律得到了材料的总体刚度, 进而得到一阶固有频率。此外, 还分别计算了一个周期内不同走向纱线和基体振动消耗的能量, 以及总振动能量, 得到了材料的损耗因子。结果表明, 对于三维四向和五向编织复合材料, 一阶固有频率随编织角的增加而减小, 随纤维体积分数的增加而增大; 而损耗因子随编织角的增加而增大, 随纤维体积分数的增加而减小, 并表现出明显的非线性变化规律。 相似文献
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为研究预制体结构及界面对三维编织SiC/SiC复合材料拉伸性能的影响,采用先驱体浸渍裂解法(PIP)分别制备了三维四向和三维五向SiC/SiC复合材料,并引入热解炭/碳化硅(PyC/SiC)复合界面层,进行拉伸性能测试和断口形貌观察。结果表明,三维五向SiC/SiC复合材料拉伸性能优于三维四向SiC/SiC复合材料,三维五向SiC/SiC复合材料的拉伸强度、模量和断裂应变分别是三维四向SiC/SiC复合材料的1.22倍、1.25倍、1.43倍,且比三维四向SiC/SiC复合材料具有更好的强度可靠性。这是由于三维五向SiC/SiC复合材料增加了受力方向的纤维含量,限制了纤维在外力作用下的转动和变形,起到定型和稳固作用。添加PyC/SiC复合界面层,三维五向SiC/SiC复合材料的拉伸强度、模量及断裂应变分别提高了21.7%、15.0%和11.0%。界面的存在可以保护纤维,调节纤维与基体之间的热应力,受力时诱使裂纹偏转和分叉,消耗能量,提高三维五向SiC/SiC复合材料的拉伸性能。 相似文献
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A new analytical model for calculation of stiffness of three-dimensional four-directional braided composites 总被引:2,自引:0,他引:2
The present paper represents a new analytical method for calculation of the stiffness of three-dimensional four-directional braided composites. In most previous works, the analytical approach had been largely neglected in the favor of the finite element model. Among those who have used the analytical model, the braided preform has been considered as made of one, or three, types of representative unit cells, while microscopic evidence of the microstructure of preforms reveals different configurations of the yarns in the interior, surface and corner regions of a braided preform. This paper presents a Multi-Unit Cell Model in which four kinds of unit cells, namely interior, interior surface, exterior surface and corner unit cells have been introduced as representative cells. Each type of unit cell in a braided composite possesses unique mechanical properties and has been considered as a uni-directional composite. Using rotation matrices, the angle between yarns and longitudinal direction has been incorporated in general coordinates of the model. Finally, using a volume averaging method, the total stiffness of the braided composite is calculated. The results are in good agreement with the available experimental data. The effect of braiding angle on the stiffness of braided composites is also examined. 相似文献