真空压力浸渗制备CF/Al复合材料热收缩与残余应力数值模拟与实验研究

Numerical Simulation and Experimental Study on Thermal Shrinkage and Residual Stress of CF / Al Composite Prepared by Vacuum Pressure Infiltration

摘要:

针对连续碳纤维增强铝基复合材料(CF/Al复合材料),采用细观力学数值模拟与热性能试验结合的方法,研究了真空压力浸渗制备过程中的热收缩行为和热残余应力分布。结果表明,复合材料的横向热收缩应变量远大于轴向热收缩应变量,且具有横观各向同性,纤维随机分布的单胞有限元模型能够准确地预测复合材料轴向与横向热收缩行为曲线；复合材料制备完成后纤维和基体合金分别处于压应力和拉应力状态,基体和纤维的横向残余应力均小于其轴向残余应力,且均表现出横观各向同性；基体合金在轴向残余拉应力作用下会出现不同程度的损伤现象,特别是纤维间距较小部位过高的残余应力会引发界面的局部失效,从而不利于发挥复合材料承载性能,减少纤维局部偏聚是进一步改善提高复合材料力学性能的重要技术手段。

Abstract:

For continuous carbon fiber reinforced aluminum matrix composites (CF/Al composites), the thermal shrinkage behavior and thermal residual stress distribution in the vacuum pressure infiltration preparation process were studied by combining the numerical simulation with the thermal performance test. The results show that the transverse thermal shrinkage strain of the composite is much larger than that the axial thermal shrinkage strain, and it is transversely isotropic. The radom fiber arrangement RVE model can accurately predict the axial and transverse thermal shrinkage behavior curves of the composite. In the prepared composite, the fiber and matrix alloy are in compressive stress state and tensile stress state, respectively. The transverse residual stresses of the matrix alloy and fiber is less than their axial residual stresses, and both show the transverse isotropic. The matrix alloy will appear different degrees of damage under the action of axial residual tensile stress. Especially, the high residual stress at the small fiber spacing will cause local interfacial failure, which is not conducive to the bearing capacity of the composite. It is an important technical approach to reduce the local segregation of fibers in order to improve the mechanical properties of the composite.