界面对硅酸铝短纤维增强AZ91D镁基复合材料蠕变性能的影响

界面对复合材料蠕变性能的影响很大。在试验分析的基础上建立了硅酸铝短纤维增强AZ91D镁基复合材料理论分析模型，利用三维有限元分析方法，系统研究了界面特性、界面上应力应变分布和短纤维位向变化对硅酸铝短纤维增强AZ91D镁基复合材料蠕变性能的影响。研究表明：界面特性，如厚度、模量，均对纤维最大轴应力和稳态蠕变速率有影响，当界面厚度增加，纤维最大轴应力减小而稳态蠕变速率增大；当界面模量增大，纤维最大轴应力增大而稳态蠕变速率减小，但当界面模量高于基体模量时，纤维最大轴应力和稳态蠕变速率均保持不变；纤维位向也影响轴应力分布和稳态蠕变速率，纤维在其末端界面上存在较大的应力和应变，此处容易产生微裂纹而使材料抗蠕变能力下降；界面对硅酸铝短纤维增强AZ91D镁基复合材料的蠕变曲线和蠕变断裂机制也有影响，其影响程度还与纤维位向有关。

Interface effects on creep properties of aluminum silicate short fiber reinforced AZ91D magnesium matrix composites

Interface has great influence on the creep properties of composites. A theoretical analysis model was established for aluminum silicate short fiber reinforced AZ91D magnesium matrix composites on the basis of test analysis, and by using 3D finite element analysis method, the effects of interface properties, stress and strain distribution on the interface and short fiber orientation change on the creep properties of aluminum silicate short fiber reinforced AZ91D magnesium matrix composites were systematically investigated. The research shows that the interface properties such as thickness and modulus, have effects on the maximum fiber axial stress and steady-state creep rate. The maximum fiber axial stress decreases with the increasing of interface thickness, and increases with the increasing of interface modulus. The steady-state creep rate increases with the increasing of interface thickness, and decreases with the increasing of interface modulus. Both remain unchanged when the interface modulus is bigger than the matrix modulus. The short fiber orientation also affects the distribution of the axial stress and steady-state creep rate. There is a greater stress and strain on the interface of the fiber end where microcracks are easily produced, which decreases the creep resistance of the material. The interface can affect creep curves and creep fracture mechanism of aluminum silicate short fiber reinforced AZ91D magnesium matrix composites, and the impact is also related with short fiber orientation.