基于单向陶瓷基复合材料拉伸曲线的细观力学参数识别

Identification of Micromechanical Parameters of Unidirectional Ceramics Matrix Composites Based on Tensile Curves

关键词:  单向陶瓷基复合材料  轴向拉伸曲线  剪滞模型  细观力学参数  参数识别

Key words:  Unidirectional ceramic matrix composites  Axial tensile curve  Shear-lag model  Microstructure parameters  Parameters identification

摘要:

为了确定陶瓷基复合材料组分材料的细观力学参数，对陶瓷基复合材料拉伸曲线与细观力学参数之间的关系进行了研究，提出了基于单向陶瓷基复合材料拉伸曲线的细观力学参数的识别方法。单向陶瓷基复合材料典型的拉伸曲线可分为三段:初始线性段、过渡段以及第二线性段。基于剪滞模型，建立单向拉伸曲线初始线性段的斜率、第二线性段的斜率以及截距的表达式，并将理论值与实验值进行比较，从而识别出细观力学参数。最后将识别出的细观力学参数带入剪滞模型，并预测SiC/SiC单向陶瓷基复合材料的轴向拉伸应力应变曲线。预测结果与实验吻合很好，说明该细观力学参数的识别方法是可行的。同时采用另一种方法测量纤维弹性模量。两种方法的测量偏差小于5%，进一步证明了本文方法是合理的。

Abstract:

In order to determinate the micromechanical parameters of constituents of ceramic matrix composites (CMCs)， the relation between the tensile curves and micromechanical parameters of unidirectional CMCs (UD-CMCs) was investigated. And the micromechanical parameter identification method based on tensile curves of UD-CMCs was proposed. The typical tensile curve of UD-CMCs can be divided into three parts: an initial linear segment， a transition segment and a second linear segment. The theoretical expression of slope of the initial linear segment， the slope and intercept of the second linear segment on the function of micromechanical parameters were obtained based on the shear-lag model. The micromechanical parameters can be identified by comparing the theoretical curve with the experimental curve. Lastly， all identified micromechanical parameters were taken into shear-lag model and the predicted axial tensile curve of the UD-CMCs of SiC/SiC was obtained. The predicted curve fits well with the experimental curve， which proves the method proposed is feasible. Meanwhile， another method was used to measure the elastic modulus of the fiber. The difference between the two methods is less than 5%， which further proves that the method in this paper is reasonable.