2D-C/SiC复合材料的面内剪切本构模型

In-plane shear constitutive model for 2D-C/SiC composites

为了表征2D-C/SiC复合材料的面内剪切行为,考虑基体开裂、界面脱粘、纤维桥连弯曲等损伤机制,提出宏细观两尺度下的含损伤体元模型;引入热失配应力的影响,在分别表征卸载弹性应变和残余应变的基础上,建立材料的温度相关面内剪切本构模型。开展室温单调加载和加卸载面内剪切实验,发现残余应变和弹性应变均随剪应力的增大逐渐增大,而卸载模量随剪应力的增大持续减小。将模型用于2D-C/SiC复合材料剪切行为的模拟,结果表明:模型对于弹性应变、残余应变、卸载模量和整体应力-应变曲线的预测值均与实验数据吻合,验证了分析模型的合理性与准确性;在此基础上,给出2D-C/SiC复合材料在不同温度下的面内剪切应力-应变关系曲线,为热结构设计提供参考。

In order to characterize in-plane shear behavior of 2D-C/SiC composites,a macroscopic cross-ply laminate model and a microscopic mini-composite model were proposed,considering damage mechanisms such as matrix cracking,interface debonding,and fiber bridging and bending.By introducing the influence of thermal misfit stress and characterizing both the unloading elastic strain and residual strain,a temperature-dependent in-plane shear constitutive model for the material was established.In-plane shear tests with 2D-C/SiC composites were performed at room temperature to validate the model.It is found that the residual strain and elastic strain increase while the unloading modulus decreases gradually with increasing shear stress.The model was then used to simulate the shear behavior.The results show that the predictions of elastic strain,residual strain,unloading modulus,and apparent stress-strain relationship are all consistent with the tested data,which preliminarily illustrates the reasonability and accuracy of the analytical model.On this basis,the in-plane shear stress-strain curves of 2D-C/SiC composites at different temperatures are presented,providing a reference for thermal structure design.