Li Wenli, Zhu Donghui, Shao Wenqi, Jiang Dong
School of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, China.
Materials (Basel). 2022 Aug 3;15(15):5332. doi: 10.3390/ma15155332.
Due to the advantages of high specific strength, specific stiffness, and excellent fatigue resistance, carbon fiber reinforced braided composites have been widely applied in engineering. Since the molding process of braided composites is complex and immature, substantial variability of the internal geometry exists in composites, in which the yarn path with uncertainty is a main factor, so it is necessary to establish an uncertainty model to study the influence of randomness of the yarn path on mechanical properties, which is significantly related to the fatigue resistance properties of composite. An uncertain mesoscopic model with uniform distribution of yarn paths is proposed. Assuming the yarn path is spatially varying in interval range, the variability of yarn path is represented geometrically in the unit cell of composite. The three-dimensional coordinates of the yarn trajectory are calculated, the meso-uncertainty models of 2-D and 2.5-D braided composites are established. The equivalent elastic parameters and the thermal expansion coefficients are obtained by applying homogenization method and temperature field boundary conditions to the mesoscopic model. The effect of yarn path uncertainty on the statistical characteristics of elastic and thermal parameters of braided composites was studied by using Monte-Carlo simulation. A simulation method for modeling yarn path uncertainty of braided composites is provided in this paper for predicting the statistical characteristics of the equivalent elastic and thermal parameters.
由于具有高比强度、高比刚度以及优异的抗疲劳性能等优点，碳纤维增强编织复合材料在工程领域得到了广泛应用。由于编织复合材料的成型工艺复杂且不成熟，复合材料内部几何结构存在很大的变异性，其中纱线路径的不确定性是一个主要因素，因此有必要建立一个不确定性模型来研究纱线路径随机性对力学性能的影响，这与复合材料的抗疲劳性能密切相关。提出了一种纱线路径均匀分布的细观不确定性模型。假设纱线路径在区间范围内呈空间变化，纱线路径的变异性在复合材料的单胞中以几何形式表示。计算纱线轨迹的三维坐标，建立二维和2.5维编织复合材料的细观不确定性模型。通过对细观模型施加均匀化方法和温度场边界条件，得到等效弹性参数和热膨胀系数。利用蒙特卡洛模拟研究了纱线路径不确定性对编织复合材料弹性和热参数统计特性的影响。本文提供了一种编织复合材料纱线路径不确定性建模的模拟方法，用于预测等效弹性和热参数的统计特性。
