二维机织C/SiC复合材料非线性力学行为数值模拟

建立了考虑纤维束内部缺陷以及外部基体缺陷的多尺度单胞模型。首先依据电镜扫描图和材料内部单胞的密度,确定了纤维束单胞和复合材料单胞的几何尺寸;然后引入周期性边界条件,利用含缺陷的纤维束单胞模型计算了其初始模量和强度;最后使用由电镜扫描图确定尺寸的复合材料单胞模型,利用上一尺度的材料参数,对复合材料的模量进行了预测;并建立了含损伤纤维束单胞的刚度矩阵,运用基于不同失效模式下损伤状态变量的刚度渐进折减法表征材料积分点损伤,通过数值结果与试验结果的对比,分析了Hashin准则作为判定纤维束起始损伤的适用性,并最终据此给出了单轴载荷作用下受损材料参数的变化情况。分析表明:基于考虑两种缺陷的多尺度模型,使用Hashin准则对C/Si C复合材料单胞进行非线性应力-应变行为数值预报与实验吻合良好。

Numerical Simulation of Nonlinear Mechanics Behavior for 2D Weave Composites

Considering the defect into fiber bundle and outer matrix,a multiscale unit-cell model is establiashed.At first,according to the scanning electron microscope(SEM) photograph and the density into the material,the geometric dimensioning of the unit-cell of fiber bundle and composite is confirmed.Then,introducing into the periodic boundary condition,the initial modulus and strength are calculated by using the fiber bundle unit-cell containing defects.At last,using the composite unit-cell model which confirming geometric dimensioning by SEM photograph,the stiffness is predicted by the material parameters from previous scale.The stiffness matrix of the damaged unit-cell for fiber bundle was established.The damage evolvement method by introducing damage variables of different damage modes were considered as the progressive damage of the material integral points.It was analyzed and discussed by comparing numerical predictions with experimental data.And the damaged material properties under uniaxial load are given at last.The results indicate that numerical simulation of the nonlinear stress-strain behavior based on Hashin failure criteria with various damage modes gives good agreement compared to experimental results.