三维机织复合材料的一种梁单元细观力学模型

根据三维机织复合材料中纤维束排列和变形的周期性特点,推导了一种细观梁单元模型。该模型考虑了纤维束的拉 (压) 弯耦合效应和纤维束之间的相互作用,可以描述纤维束和基体中的细观应力分布,并得到宏观的力学性能。针对一种典型的三维机织复合材料,首先根据编织参数,确定其细观几何结构,取最小周期的一段纤维束作为分析胞元,用上述细观梁单元分析了该段纤维束在面内拉伸荷载下的细观应力分布,计算出平均模量, 并用材料试验和细观实体有限元对本模型进行了检验,结果与本文的预测吻合良好。研究表明,拉、弯耦合效应引起的纤维束中的细观弯曲应力同平均轴向应力相比,不可忽略。 

MICRO BEAM MODEL FOR 3D WOVEN COMPOSITE MATERIALS

A micro beam model was developed to predict the deformation and micro stress distribution of fiber yarns and matrix in three dimensionally woven composites. The shear deformation in the interlayer matrix between adjunct fiber yarns caused by yarn bending was taken into account. In this model,the fiber yarn is modeled by beams in series, therefore its tension and bending deformations are coupled. To a typical three dimensionally woven composite material the method of determining microstructure by woven parameters is discussed. An analytical cell is adopted which is constructed by a least periodic section of yarn and interlayer matrix. Micro stresses of the cell were studied by this beam model. The macro modulus of this material was obtained by averaging micro stresses of the cell. The predictions agree well with those from material test and micro brick finite element method. Analysis (reveals) that the micro stress caused by the tensile/bending coupling effect is not ignorable.