SiC/TC4复合材料横向拉伸应力集中系数的表征及试验验证

Characterization and Experimental Verification of Transverse Tensile Stress Concentration Coefficient in SiC/TC4 Composites

关键词:  复合材料  应力集中  力学性能  细观力学模型  载荷

Key words:  Composites  Stress concentration  Machanical performance  Meso-mechanical model  Load

摘要:

针对纤维均匀排布的单向纤维增强复合材料在横向拉伸荷载下基体产生应力集中的问题，提出了横向拉伸荷载下基体应力集中系数的表征方法。基于复合材料细观力学理论，通过编写程序在代表体积元（Representative Volume Element, RVE）模型上施加周期性边界条件，实现了单、双轴横向拉伸荷载下基体应力集中系数的计算，并通过单向纤维增强SiC/TC4复合材料板的横向拉伸试验验证了所建模型的有效性。利用所建模型计算不同纤维体积分数、材料组分以及温度条件下基体应力集中系数并分析其影响规律。计算结果表明：单轴横向拉伸应力集中系数随着纤维体积分数的增加而增大，双轴横向拉伸应力集中系数随着纤维体积分数的增加呈现出先减小后增大的趋势；在20℃~500℃区间内，单轴横向拉伸应力集中系数最大可达2.8，双轴横向拉伸应力集中系数最大达2.4。

Abstract:

For the problem of stress concentration in the matrix of unidirectional fiber reinforced composite with uniform arranged fiber under transverse tensile load, a method to characterize the stress concentration coefficient of matrix under transverse tensile load was presented. Based on the composite micro-mechanical research method, the Representative Volume Element (RVE) model is programmed to impose periodic boundary conditions，the stress concentration coefficient of matrix under single and biaxial transverse tensile load was calculated. The validity of the model was verified by the transverse tensile test of unidirectional fiber-reinforced SiC/TC4 composite plate. Based on the established model, the stress concentration coefficient of different fiber volume fraction, material composition and temperature was calculated and the influence of them was analyzed. The simulation results show that the uniaxial transverse tensile stress concentration coefficient increases with the increase of fiber volume fraction, and the biaxial transverse tensile stress concentration coefficient decreases first and then increases with the increase of fiber volume fraction. In the range of 20℃~500℃, the maximum value of the uniaxial and the biaxial transverse tensile stress concentration coefficient is 2.8 and 2.4, respectively.